Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1619 insertions, 0 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
new file mode 100644
index 000000000..46d026542
--- /dev/null
+++ b/ipc/mqueue.c
@@ -0,0 +1,1619 @@
+/*
+ * POSIX message queues filesystem for Linux.
+ *
+ * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
+ *                          Michal Wronski          (michal.wronski@gmail.com)
+ *
+ * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
+ * Lockless receive & send, fd based notify:
+ *			    Manfred Spraul	    (manfred@colorfullife.com)
+ *
+ * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/capability.h>
+#include <linux/init.h>
+#include <linux/pagemap.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/sysctl.h>
+#include <linux/poll.h>
+#include <linux/mqueue.h>
+#include <linux/msg.h>
+#include <linux/skbuff.h>
+#include <linux/vmalloc.h>
+#include <linux/netlink.h>
+#include <linux/syscalls.h>
+#include <linux/audit.h>
+#include <linux/signal.h>
+#include <linux/mutex.h>
+#include <linux/nsproxy.h>
+#include <linux/pid.h>
+#include <linux/ipc_namespace.h>
+#include <linux/user_namespace.h>
+#include <linux/slab.h>
+#include <linux/sched/wake_q.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/user.h>
+
+#include <net/sock.h>
+#include "util.h"
+
+#define MQUEUE_MAGIC	0x19800202
+#define DIRENT_SIZE	20
+#define FILENT_SIZE	80
+
+#define SEND		0
+#define RECV		1
+
+#define STATE_NONE	0
+#define STATE_READY	1
+
+struct posix_msg_tree_node {
+	struct rb_node		rb_node;
+	struct list_head	msg_list;
+	int			priority;
+};
+
+struct ext_wait_queue {		/* queue of sleeping tasks */
+	struct task_struct *task;
+	struct list_head list;
+	struct msg_msg *msg;	/* ptr of loaded message */
+	int state;		/* one of STATE_* values */
+};
+
+struct mqueue_inode_info {
+	spinlock_t lock;
+	struct inode vfs_inode;
+	wait_queue_head_t wait_q;
+
+	struct rb_root msg_tree;
+	struct posix_msg_tree_node *node_cache;
+	struct mq_attr attr;
+
+	struct sigevent notify;
+	struct pid *notify_owner;
+	u32 notify_self_exec_id;
+	struct user_namespace *notify_user_ns;
+	struct user_struct *user;	/* user who created, for accounting */
+	struct sock *notify_sock;
+	struct sk_buff *notify_cookie;
+
+	/* for tasks waiting for free space and messages, respectively */
+	struct ext_wait_queue e_wait_q[2];
+
+	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
+};
+
+static const struct inode_operations mqueue_dir_inode_operations;
+static const struct file_operations mqueue_file_operations;
+static const struct super_operations mqueue_super_ops;
+static void remove_notification(struct mqueue_inode_info *info);
+
+static struct kmem_cache *mqueue_inode_cachep;
+
+static struct ctl_table_header *mq_sysctl_table;
+
+static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
+{
+	return container_of(inode, struct mqueue_inode_info, vfs_inode);
+}
+
+/*
+ * This routine should be called with the mq_lock held.
+ */
+static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
+{
+	return get_ipc_ns(inode->i_sb->s_fs_info);
+}
+
+static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
+{
+	struct ipc_namespace *ns;
+
+	spin_lock(&mq_lock);
+	ns = __get_ns_from_inode(inode);
+	spin_unlock(&mq_lock);
+	return ns;
+}
+
+/* Auxiliary functions to manipulate messages' list */
+static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
+{
+	struct rb_node **p, *parent = NULL;
+	struct posix_msg_tree_node *leaf;
+
+	p = &info->msg_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
+
+		if (likely(leaf->priority == msg->m_type))
+			goto insert_msg;
+		else if (msg->m_type < leaf->priority)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+	if (info->node_cache) {
+		leaf = info->node_cache;
+		info->node_cache = NULL;
+	} else {
+		leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
+		if (!leaf)
+			return -ENOMEM;
+		INIT_LIST_HEAD(&leaf->msg_list);
+	}
+	leaf->priority = msg->m_type;
+	rb_link_node(&leaf->rb_node, parent, p);
+	rb_insert_color(&leaf->rb_node, &info->msg_tree);
+insert_msg:
+	info->attr.mq_curmsgs++;
+	info->qsize += msg->m_ts;
+	list_add_tail(&msg->m_list, &leaf->msg_list);
+	return 0;
+}
+
+static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
+{
+	struct rb_node **p, *parent = NULL;
+	struct posix_msg_tree_node *leaf;
+	struct msg_msg *msg;
+
+try_again:
+	p = &info->msg_tree.rb_node;
+	while (*p) {
+		parent = *p;
+		/*
+		 * During insert, low priorities go to the left and high to the
+		 * right.  On receive, we want the highest priorities first, so
+		 * walk all the way to the right.
+		 */
+		p = &(*p)->rb_right;
+	}
+	if (!parent) {
+		if (info->attr.mq_curmsgs) {
+			pr_warn_once("Inconsistency in POSIX message queue, "
+				     "no tree element, but supposedly messages "
+				     "should exist!\n");
+			info->attr.mq_curmsgs = 0;
+		}
+		return NULL;
+	}
+	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
+	if (unlikely(list_empty(&leaf->msg_list))) {
+		pr_warn_once("Inconsistency in POSIX message queue, "
+			     "empty leaf node but we haven't implemented "
+			     "lazy leaf delete!\n");
+		rb_erase(&leaf->rb_node, &info->msg_tree);
+		if (info->node_cache) {
+			kfree(leaf);
+		} else {
+			info->node_cache = leaf;
+		}
+		goto try_again;
+	} else {
+		msg = list_first_entry(&leaf->msg_list,
+				       struct msg_msg, m_list);
+		list_del(&msg->m_list);
+		if (list_empty(&leaf->msg_list)) {
+			rb_erase(&leaf->rb_node, &info->msg_tree);
+			if (info->node_cache) {
+				kfree(leaf);
+			} else {
+				info->node_cache = leaf;
+			}
+		}
+	}
+	info->attr.mq_curmsgs--;
+	info->qsize -= msg->m_ts;
+	return msg;
+}
+
+static struct inode *mqueue_get_inode(struct super_block *sb,
+		struct ipc_namespace *ipc_ns, umode_t mode,
+		struct mq_attr *attr)
+{
+	struct user_struct *u = current_user();
+	struct inode *inode;
+	int ret = -ENOMEM;
+
+	inode = new_inode(sb);
+	if (!inode)
+		goto err;
+
+	inode->i_ino = get_next_ino();
+	inode->i_mode = mode;
+	inode->i_uid = current_fsuid();
+	inode->i_gid = current_fsgid();
+	inode->i_mtime = inode->i_ctime = inode->i_atime = current_time(inode);
+
+	if (S_ISREG(mode)) {
+		struct mqueue_inode_info *info;
+		unsigned long mq_bytes, mq_treesize;
+
+		inode->i_fop = &mqueue_file_operations;
+		inode->i_size = FILENT_SIZE;
+		/* mqueue specific info */
+		info = MQUEUE_I(inode);
+		spin_lock_init(&info->lock);
+		init_waitqueue_head(&info->wait_q);
+		INIT_LIST_HEAD(&info->e_wait_q[0].list);
+		INIT_LIST_HEAD(&info->e_wait_q[1].list);
+		info->notify_owner = NULL;
+		info->notify_user_ns = NULL;
+		info->qsize = 0;
+		info->user = NULL;	/* set when all is ok */
+		info->msg_tree = RB_ROOT;
+		info->node_cache = NULL;
+		memset(&info->attr, 0, sizeof(info->attr));
+		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
+					   ipc_ns->mq_msg_default);
+		info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
+					    ipc_ns->mq_msgsize_default);
+		if (attr) {
+			info->attr.mq_maxmsg = attr->mq_maxmsg;
+			info->attr.mq_msgsize = attr->mq_msgsize;
+		}
+		/*
+		 * We used to allocate a static array of pointers and account
+		 * the size of that array as well as one msg_msg struct per
+		 * possible message into the queue size. That's no longer
+		 * accurate as the queue is now an rbtree and will grow and
+		 * shrink depending on usage patterns.  We can, however, still
+		 * account one msg_msg struct per message, but the nodes are
+		 * allocated depending on priority usage, and most programs
+		 * only use one, or a handful, of priorities.  However, since
+		 * this is pinned memory, we need to assume worst case, so
+		 * that means the min(mq_maxmsg, max_priorities) * struct
+		 * posix_msg_tree_node.
+		 */
+
+		ret = -EINVAL;
+		if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
+			goto out_inode;
+		if (capable(CAP_SYS_RESOURCE)) {
+			if (info->attr.mq_maxmsg > HARD_MSGMAX ||
+			    info->attr.mq_msgsize > HARD_MSGSIZEMAX)
+				goto out_inode;
+		} else {
+			if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
+					info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
+				goto out_inode;
+		}
+		ret = -EOVERFLOW;
+		/* check for overflow */
+		if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
+			goto out_inode;
+		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
+			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
+			sizeof(struct posix_msg_tree_node);
+		mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
+		if (mq_bytes + mq_treesize < mq_bytes)
+			goto out_inode;
+		mq_bytes += mq_treesize;
+		spin_lock(&mq_lock);
+		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
+		    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
+			spin_unlock(&mq_lock);
+			/* mqueue_evict_inode() releases info->messages */
+			ret = -EMFILE;
+			goto out_inode;
+		}
+		u->mq_bytes += mq_bytes;
+		spin_unlock(&mq_lock);
+
+		/* all is ok */
+		info->user = get_uid(u);
+	} else if (S_ISDIR(mode)) {
+		inc_nlink(inode);
+		/* Some things misbehave if size == 0 on a directory */
+		inode->i_size = 2 * DIRENT_SIZE;
+		inode->i_op = &mqueue_dir_inode_operations;
+		inode->i_fop = &simple_dir_operations;
+	}
+
+	return inode;
+out_inode:
+	iput(inode);
+err:
+	return ERR_PTR(ret);
+}
+
+static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+	struct ipc_namespace *ns = sb->s_fs_info;
+
+	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
+	sb->s_blocksize = PAGE_SIZE;
+	sb->s_blocksize_bits = PAGE_SHIFT;
+	sb->s_magic = MQUEUE_MAGIC;
+	sb->s_op = &mqueue_super_ops;
+
+	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	sb->s_root = d_make_root(inode);
+	if (!sb->s_root)
+		return -ENOMEM;
+	return 0;
+}
+
+static struct dentry *mqueue_mount(struct file_system_type *fs_type,
+			 int flags, const char *dev_name,
+			 void *data)
+{
+	struct ipc_namespace *ns;
+	if (flags & SB_KERNMOUNT) {
+		ns = data;
+		data = NULL;
+	} else {
+		ns = current->nsproxy->ipc_ns;
+	}
+	return mount_ns(fs_type, flags, data, ns, ns->user_ns, mqueue_fill_super);
+}
+
+static void init_once(void *foo)
+{
+	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
+
+	inode_init_once(&p->vfs_inode);
+}
+
+static struct inode *mqueue_alloc_inode(struct super_block *sb)
+{
+	struct mqueue_inode_info *ei;
+
+	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
+	if (!ei)
+		return NULL;
+	return &ei->vfs_inode;
+}
+
+static void mqueue_i_callback(struct rcu_head *head)
+{
+	struct inode *inode = container_of(head, struct inode, i_rcu);
+	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
+}
+
+static void mqueue_destroy_inode(struct inode *inode)
+{
+	call_rcu(&inode->i_rcu, mqueue_i_callback);
+}
+
+static void mqueue_evict_inode(struct inode *inode)
+{
+	struct mqueue_inode_info *info;
+	struct user_struct *user;
+	struct ipc_namespace *ipc_ns;
+	struct msg_msg *msg, *nmsg;
+	LIST_HEAD(tmp_msg);
+
+	clear_inode(inode);
+
+	if (S_ISDIR(inode->i_mode))
+		return;
+
+	ipc_ns = get_ns_from_inode(inode);
+	info = MQUEUE_I(inode);
+	spin_lock(&info->lock);
+	while ((msg = msg_get(info)) != NULL)
+		list_add_tail(&msg->m_list, &tmp_msg);
+	kfree(info->node_cache);
+	spin_unlock(&info->lock);
+
+	list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
+		list_del(&msg->m_list);
+		free_msg(msg);
+	}
+
+	user = info->user;
+	if (user) {
+		unsigned long mq_bytes, mq_treesize;
+
+		/* Total amount of bytes accounted for the mqueue */
+		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
+			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
+			sizeof(struct posix_msg_tree_node);
+
+		mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
+					  info->attr.mq_msgsize);
+
+		spin_lock(&mq_lock);
+		user->mq_bytes -= mq_bytes;
+		/*
+		 * get_ns_from_inode() ensures that the
+		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
+		 * to which we now hold a reference, or it is NULL.
+		 * We can't put it here under mq_lock, though.
+		 */
+		if (ipc_ns)
+			ipc_ns->mq_queues_count--;
+		spin_unlock(&mq_lock);
+		free_uid(user);
+	}
+	if (ipc_ns)
+		put_ipc_ns(ipc_ns);
+}
+
+static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct inode *inode;
+	struct mq_attr *attr = arg;
+	int error;
+	struct ipc_namespace *ipc_ns;
+
+	spin_lock(&mq_lock);
+	ipc_ns = __get_ns_from_inode(dir);
+	if (!ipc_ns) {
+		error = -EACCES;
+		goto out_unlock;
+	}
+
+	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
+	    !capable(CAP_SYS_RESOURCE)) {
+		error = -ENOSPC;
+		goto out_unlock;
+	}
+	ipc_ns->mq_queues_count++;
+	spin_unlock(&mq_lock);
+
+	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
+	if (IS_ERR(inode)) {
+		error = PTR_ERR(inode);
+		spin_lock(&mq_lock);
+		ipc_ns->mq_queues_count--;
+		goto out_unlock;
+	}
+
+	put_ipc_ns(ipc_ns);
+	dir->i_size += DIRENT_SIZE;
+	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
+
+	d_instantiate(dentry, inode);
+	dget(dentry);
+	return 0;
+out_unlock:
+	spin_unlock(&mq_lock);
+	if (ipc_ns)
+		put_ipc_ns(ipc_ns);
+	return error;
+}
+
+static int mqueue_create(struct inode *dir, struct dentry *dentry,
+				umode_t mode, bool excl)
+{
+	return mqueue_create_attr(dentry, mode, NULL);
+}
+
+static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+
+	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
+	dir->i_size -= DIRENT_SIZE;
+	drop_nlink(inode);
+	dput(dentry);
+	return 0;
+}
+
+/*
+*	This is routine for system read from queue file.
+*	To avoid mess with doing here some sort of mq_receive we allow
+*	to read only queue size & notification info (the only values
+*	that are interesting from user point of view and aren't accessible
+*	through std routines)
+*/
+static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
+				size_t count, loff_t *off)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
+	char buffer[FILENT_SIZE];
+	ssize_t ret;
+
+	spin_lock(&info->lock);
+	snprintf(buffer, sizeof(buffer),
+			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
+			info->qsize,
+			info->notify_owner ? info->notify.sigev_notify : 0,
+			(info->notify_owner &&
+			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
+				info->notify.sigev_signo : 0,
+			pid_vnr(info->notify_owner));
+	spin_unlock(&info->lock);
+	buffer[sizeof(buffer)-1] = '\0';
+
+	ret = simple_read_from_buffer(u_data, count, off, buffer,
+				strlen(buffer));
+	if (ret <= 0)
+		return ret;
+
+	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp));
+	return ret;
+}
+
+static int mqueue_flush_file(struct file *filp, fl_owner_t id)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
+
+	spin_lock(&info->lock);
+	if (task_tgid(current) == info->notify_owner)
+		remove_notification(info);
+
+	spin_unlock(&info->lock);
+	return 0;
+}
+
+static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
+{
+	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
+	__poll_t retval = 0;
+
+	poll_wait(filp, &info->wait_q, poll_tab);
+
+	spin_lock(&info->lock);
+	if (info->attr.mq_curmsgs)
+		retval = EPOLLIN | EPOLLRDNORM;
+
+	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
+		retval |= EPOLLOUT | EPOLLWRNORM;
+	spin_unlock(&info->lock);
+
+	return retval;
+}
+
+/* Adds current to info->e_wait_q[sr] before element with smaller prio */
+static void wq_add(struct mqueue_inode_info *info, int sr,
+			struct ext_wait_queue *ewp)
+{
+	struct ext_wait_queue *walk;
+
+	ewp->task = current;
+
+	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
+		if (walk->task->prio <= current->prio) {
+			list_add_tail(&ewp->list, &walk->list);
+			return;
+		}
+	}
+	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
+}
+
+/*
+ * Puts current task to sleep. Caller must hold queue lock. After return
+ * lock isn't held.
+ * sr: SEND or RECV
+ */
+static int wq_sleep(struct mqueue_inode_info *info, int sr,
+		    ktime_t *timeout, struct ext_wait_queue *ewp)
+	__releases(&info->lock)
+{
+	int retval;
+	signed long time;
+
+	wq_add(info, sr, ewp);
+
+	for (;;) {
+		__set_current_state(TASK_INTERRUPTIBLE);
+
+		spin_unlock(&info->lock);
+		time = schedule_hrtimeout_range_clock(timeout, 0,
+			HRTIMER_MODE_ABS, CLOCK_REALTIME);
+
+		if (ewp->state == STATE_READY) {
+			retval = 0;
+			goto out;
+		}
+		spin_lock(&info->lock);
+		if (ewp->state == STATE_READY) {
+			retval = 0;
+			goto out_unlock;
+		}
+		if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			break;
+		}
+		if (time == 0) {
+			retval = -ETIMEDOUT;
+			break;
+		}
+	}
+	list_del(&ewp->list);
+out_unlock:
+	spin_unlock(&info->lock);
+out:
+	return retval;
+}
+
+/*
+ * Returns waiting task that should be serviced first or NULL if none exists
+ */
+static struct ext_wait_queue *wq_get_first_waiter(
+		struct mqueue_inode_info *info, int sr)
+{
+	struct list_head *ptr;
+
+	ptr = info->e_wait_q[sr].list.prev;
+	if (ptr == &info->e_wait_q[sr].list)
+		return NULL;
+	return list_entry(ptr, struct ext_wait_queue, list);
+}
+
+
+static inline void set_cookie(struct sk_buff *skb, char code)
+{
+	((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
+}
+
+/*
+ * The next function is only to split too long sys_mq_timedsend
+ */
+static void __do_notify(struct mqueue_inode_info *info)
+{
+	/* notification
+	 * invoked when there is registered process and there isn't process
+	 * waiting synchronously for message AND state of queue changed from
+	 * empty to not empty. Here we are sure that no one is waiting
+	 * synchronously. */
+	if (info->notify_owner &&
+	    info->attr.mq_curmsgs == 1) {
+		switch (info->notify.sigev_notify) {
+		case SIGEV_NONE:
+			break;
+		case SIGEV_SIGNAL: {
+			struct siginfo sig_i;
+			struct task_struct *task;
+
+			/* do_mq_notify() accepts sigev_signo == 0, why?? */
+			if (!info->notify.sigev_signo)
+				break;
+
+			clear_siginfo(&sig_i);
+			sig_i.si_signo = info->notify.sigev_signo;
+			sig_i.si_errno = 0;
+			sig_i.si_code = SI_MESGQ;
+			sig_i.si_value = info->notify.sigev_value;
+			rcu_read_lock();
+			/* map current pid/uid into info->owner's namespaces */
+			sig_i.si_pid = task_tgid_nr_ns(current,
+						ns_of_pid(info->notify_owner));
+			sig_i.si_uid = from_kuid_munged(info->notify_user_ns,
+						current_uid());
+			/*
+			 * We can't use kill_pid_info(), this signal should
+			 * bypass check_kill_permission(). It is from kernel
+			 * but si_fromuser() can't know this.
+			 * We do check the self_exec_id, to avoid sending
+			 * signals to programs that don't expect them.
+			 */
+			task = pid_task(info->notify_owner, PIDTYPE_TGID);
+			if (task && task->self_exec_id ==
+						info->notify_self_exec_id) {
+				do_send_sig_info(info->notify.sigev_signo,
+						&sig_i, task, PIDTYPE_TGID);
+			}
+			rcu_read_unlock();
+			break;
+		}
+		case SIGEV_THREAD:
+			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
+			netlink_sendskb(info->notify_sock, info->notify_cookie);
+			break;
+		}
+		/* after notification unregisters process */
+		put_pid(info->notify_owner);
+		put_user_ns(info->notify_user_ns);
+		info->notify_owner = NULL;
+		info->notify_user_ns = NULL;
+	}
+	wake_up(&info->wait_q);
+}
+
+static int prepare_timeout(const struct __kernel_timespec __user *u_abs_timeout,
+			   struct timespec64 *ts)
+{
+	if (get_timespec64(ts, u_abs_timeout))
+		return -EFAULT;
+	if (!timespec64_valid(ts))
+		return -EINVAL;
+	return 0;
+}
+
+static void remove_notification(struct mqueue_inode_info *info)
+{
+	if (info->notify_owner != NULL &&
+	    info->notify.sigev_notify == SIGEV_THREAD) {
+		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
+		netlink_sendskb(info->notify_sock, info->notify_cookie);
+	}
+	put_pid(info->notify_owner);
+	put_user_ns(info->notify_user_ns);
+	info->notify_owner = NULL;
+	info->notify_user_ns = NULL;
+}
+
+static int prepare_open(struct dentry *dentry, int oflag, int ro,
+			umode_t mode, struct filename *name,
+			struct mq_attr *attr)
+{
+	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
+						  MAY_READ | MAY_WRITE };
+	int acc;
+
+	if (d_really_is_negative(dentry)) {
+		if (!(oflag & O_CREAT))
+			return -ENOENT;
+		if (ro)
+			return ro;
+		audit_inode_parent_hidden(name, dentry->d_parent);
+		return vfs_mkobj(dentry, mode & ~current_umask(),
+				  mqueue_create_attr, attr);
+	}
+	/* it already existed */
+	audit_inode(name, dentry, 0);
+	if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
+		return -EEXIST;
+	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
+		return -EINVAL;
+	acc = oflag2acc[oflag & O_ACCMODE];
+	return inode_permission(d_inode(dentry), acc);
+}
+
+static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
+		      struct mq_attr *attr)
+{
+	struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt;
+	struct dentry *root = mnt->mnt_root;
+	struct filename *name;
+	struct path path;
+	int fd, error;
+	int ro;
+
+	audit_mq_open(oflag, mode, attr);
+
+	if (IS_ERR(name = getname(u_name)))
+		return PTR_ERR(name);
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		goto out_putname;
+
+	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
+	inode_lock(d_inode(root));
+	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
+	if (IS_ERR(path.dentry)) {
+		error = PTR_ERR(path.dentry);
+		goto out_putfd;
+	}
+	path.mnt = mntget(mnt);
+	error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
+	if (!error) {
+		struct file *file = dentry_open(&path, oflag, current_cred());
+		if (!IS_ERR(file))
+			fd_install(fd, file);
+		else
+			error = PTR_ERR(file);
+	}
+	path_put(&path);
+out_putfd:
+	if (error) {
+		put_unused_fd(fd);
+		fd = error;
+	}
+	inode_unlock(d_inode(root));
+	if (!ro)
+		mnt_drop_write(mnt);
+out_putname:
+	putname(name);
+	return fd;
+}
+
+SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
+		struct mq_attr __user *, u_attr)
+{
+	struct mq_attr attr;
+	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
+		return -EFAULT;
+
+	return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL);
+}
+
+SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
+{
+	int err;
+	struct filename *name;
+	struct dentry *dentry;
+	struct inode *inode = NULL;
+	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
+	struct vfsmount *mnt = ipc_ns->mq_mnt;
+
+	name = getname(u_name);
+	if (IS_ERR(name))
+		return PTR_ERR(name);
+
+	audit_inode_parent_hidden(name, mnt->mnt_root);
+	err = mnt_want_write(mnt);
+	if (err)
+		goto out_name;
+	inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
+	dentry = lookup_one_len(name->name, mnt->mnt_root,
+				strlen(name->name));
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto out_unlock;
+	}
+
+	inode = d_inode(dentry);
+	if (!inode) {
+		err = -ENOENT;
+	} else {
+		ihold(inode);
+		err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL);
+	}
+	dput(dentry);
+
+out_unlock:
+	inode_unlock(d_inode(mnt->mnt_root));
+	if (inode)
+		iput(inode);
+	mnt_drop_write(mnt);
+out_name:
+	putname(name);
+
+	return err;
+}
+
+/* Pipelined send and receive functions.
+ *
+ * If a receiver finds no waiting message, then it registers itself in the
+ * list of waiting receivers. A sender checks that list before adding the new
+ * message into the message array. If there is a waiting receiver, then it
+ * bypasses the message array and directly hands the message over to the
+ * receiver. The receiver accepts the message and returns without grabbing the
+ * queue spinlock:
+ *
+ * - Set pointer to message.
+ * - Queue the receiver task for later wakeup (without the info->lock).
+ * - Update its state to STATE_READY. Now the receiver can continue.
+ * - Wake up the process after the lock is dropped. Should the process wake up
+ *   before this wakeup (due to a timeout or a signal) it will either see
+ *   STATE_READY and continue or acquire the lock to check the state again.
+ *
+ * The same algorithm is used for senders.
+ */
+
+/* pipelined_send() - send a message directly to the task waiting in
+ * sys_mq_timedreceive() (without inserting message into a queue).
+ */
+static inline void pipelined_send(struct wake_q_head *wake_q,
+				  struct mqueue_inode_info *info,
+				  struct msg_msg *message,
+				  struct ext_wait_queue *receiver)
+{
+	receiver->msg = message;
+	list_del(&receiver->list);
+	wake_q_add(wake_q, receiver->task);
+	/*
+	 * Rely on the implicit cmpxchg barrier from wake_q_add such
+	 * that we can ensure that updating receiver->state is the last
+	 * write operation: As once set, the receiver can continue,
+	 * and if we don't have the reference count from the wake_q,
+	 * yet, at that point we can later have a use-after-free
+	 * condition and bogus wakeup.
+	 */
+	receiver->state = STATE_READY;
+}
+
+/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
+ * gets its message and put to the queue (we have one free place for sure). */
+static inline void pipelined_receive(struct wake_q_head *wake_q,
+				     struct mqueue_inode_info *info)
+{
+	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
+
+	if (!sender) {
+		/* for poll */
+		wake_up_interruptible(&info->wait_q);
+		return;
+	}
+	if (msg_insert(sender->msg, info))
+		return;
+
+	list_del(&sender->list);
+	wake_q_add(wake_q, sender->task);
+	sender->state = STATE_READY;
+}
+
+static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
+		size_t msg_len, unsigned int msg_prio,
+		struct timespec64 *ts)
+{
+	struct fd f;
+	struct inode *inode;
+	struct ext_wait_queue wait;
+	struct ext_wait_queue *receiver;
+	struct msg_msg *msg_ptr;
+	struct mqueue_inode_info *info;
+	ktime_t expires, *timeout = NULL;
+	struct posix_msg_tree_node *new_leaf = NULL;
+	int ret = 0;
+	DEFINE_WAKE_Q(wake_q);
+
+	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
+		return -EINVAL;
+
+	if (ts) {
+		expires = timespec64_to_ktime(*ts);
+		timeout = &expires;
+	}
+
+	audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
+
+	f = fdget(mqdes);
+	if (unlikely(!f.file)) {
+		ret = -EBADF;
+		goto out;
+	}
+
+	inode = file_inode(f.file);
+	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
+		ret = -EBADF;
+		goto out_fput;
+	}
+	info = MQUEUE_I(inode);
+	audit_file(f.file);
+
+	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
+		ret = -EBADF;
+		goto out_fput;
+	}
+
+	if (unlikely(msg_len > info->attr.mq_msgsize)) {
+		ret = -EMSGSIZE;
+		goto out_fput;
+	}
+
+	/* First try to allocate memory, before doing anything with
+	 * existing queues. */
+	msg_ptr = load_msg(u_msg_ptr, msg_len);
+	if (IS_ERR(msg_ptr)) {
+		ret = PTR_ERR(msg_ptr);
+		goto out_fput;
+	}
+	msg_ptr->m_ts = msg_len;
+	msg_ptr->m_type = msg_prio;
+
+	/*
+	 * msg_insert really wants us to have a valid, spare node struct so
+	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
+	 * fall back to that if necessary.
+	 */
+	if (!info->node_cache)
+		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
+
+	spin_lock(&info->lock);
+
+	if (!info->node_cache && new_leaf) {
+		/* Save our speculative allocation into the cache */
+		INIT_LIST_HEAD(&new_leaf->msg_list);
+		info->node_cache = new_leaf;
+		new_leaf = NULL;
+	} else {
+		kfree(new_leaf);
+	}
+
+	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
+		if (f.file->f_flags & O_NONBLOCK) {
+			ret = -EAGAIN;
+		} else {
+			wait.task = current;
+			wait.msg = (void *) msg_ptr;
+			wait.state = STATE_NONE;
+			ret = wq_sleep(info, SEND, timeout, &wait);
+			/*
+			 * wq_sleep must be called with info->lock held, and
+			 * returns with the lock released
+			 */
+			goto out_free;
+		}
+	} else {
+		receiver = wq_get_first_waiter(info, RECV);
+		if (receiver) {
+			pipelined_send(&wake_q, info, msg_ptr, receiver);
+		} else {
+			/* adds message to the queue */
+			ret = msg_insert(msg_ptr, info);
+			if (ret)
+				goto out_unlock;
+			__do_notify(info);
+		}
+		inode->i_atime = inode->i_mtime = inode->i_ctime =
+				current_time(inode);
+	}
+out_unlock:
+	spin_unlock(&info->lock);
+	wake_up_q(&wake_q);
+out_free:
+	if (ret)
+		free_msg(msg_ptr);
+out_fput:
+	fdput(f);
+out:
+	return ret;
+}
+
+static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
+		size_t msg_len, unsigned int __user *u_msg_prio,
+		struct timespec64 *ts)
+{
+	ssize_t ret;
+	struct msg_msg *msg_ptr;
+	struct fd f;
+	struct inode *inode;
+	struct mqueue_inode_info *info;
+	struct ext_wait_queue wait;
+	ktime_t expires, *timeout = NULL;
+	struct posix_msg_tree_node *new_leaf = NULL;
+
+	if (ts) {
+		expires = timespec64_to_ktime(*ts);
+		timeout = &expires;
+	}
+
+	audit_mq_sendrecv(mqdes, msg_len, 0, ts);
+
+	f = fdget(mqdes);
+	if (unlikely(!f.file)) {
+		ret = -EBADF;
+		goto out;
+	}
+
+	inode = file_inode(f.file);
+	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
+		ret = -EBADF;
+		goto out_fput;
+	}
+	info = MQUEUE_I(inode);
+	audit_file(f.file);
+
+	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
+		ret = -EBADF;
+		goto out_fput;
+	}
+
+	/* checks if buffer is big enough */
+	if (unlikely(msg_len < info->attr.mq_msgsize)) {
+		ret = -EMSGSIZE;
+		goto out_fput;
+	}
+
+	/*
+	 * msg_insert really wants us to have a valid, spare node struct so
+	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
+	 * fall back to that if necessary.
+	 */
+	if (!info->node_cache)
+		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
+
+	spin_lock(&info->lock);
+
+	if (!info->node_cache && new_leaf) {
+		/* Save our speculative allocation into the cache */
+		INIT_LIST_HEAD(&new_leaf->msg_list);
+		info->node_cache = new_leaf;
+	} else {
+		kfree(new_leaf);
+	}
+
+	if (info->attr.mq_curmsgs == 0) {
+		if (f.file->f_flags & O_NONBLOCK) {
+			spin_unlock(&info->lock);
+			ret = -EAGAIN;
+		} else {
+			wait.task = current;
+			wait.state = STATE_NONE;
+			ret = wq_sleep(info, RECV, timeout, &wait);
+			msg_ptr = wait.msg;
+		}
+	} else {
+		DEFINE_WAKE_Q(wake_q);
+
+		msg_ptr = msg_get(info);
+
+		inode->i_atime = inode->i_mtime = inode->i_ctime =
+				current_time(inode);
+
+		/* There is now free space in queue. */
+		pipelined_receive(&wake_q, info);
+		spin_unlock(&info->lock);
+		wake_up_q(&wake_q);
+		ret = 0;
+	}
+	if (ret == 0) {
+		ret = msg_ptr->m_ts;
+
+		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
+			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
+			ret = -EFAULT;
+		}
+		free_msg(msg_ptr);
+	}
+out_fput:
+	fdput(f);
+out:
+	return ret;
+}
+
+SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
+		size_t, msg_len, unsigned int, msg_prio,
+		const struct __kernel_timespec __user *, u_abs_timeout)
+{
+	struct timespec64 ts, *p = NULL;
+	if (u_abs_timeout) {
+		int res = prepare_timeout(u_abs_timeout, &ts);
+		if (res)
+			return res;
+		p = &ts;
+	}
+	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
+}
+
+SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
+		size_t, msg_len, unsigned int __user *, u_msg_prio,
+		const struct __kernel_timespec __user *, u_abs_timeout)
+{
+	struct timespec64 ts, *p = NULL;
+	if (u_abs_timeout) {
+		int res = prepare_timeout(u_abs_timeout, &ts);
+		if (res)
+			return res;
+		p = &ts;
+	}
+	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
+}
+
+/*
+ * Notes: the case when user wants us to deregister (with NULL as pointer)
+ * and he isn't currently owner of notification, will be silently discarded.
+ * It isn't explicitly defined in the POSIX.
+ */
+static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
+{
+	int ret;
+	struct fd f;
+	struct sock *sock;
+	struct inode *inode;
+	struct mqueue_inode_info *info;
+	struct sk_buff *nc;
+
+	audit_mq_notify(mqdes, notification);
+
+	nc = NULL;
+	sock = NULL;
+	if (notification != NULL) {
+		if (unlikely(notification->sigev_notify != SIGEV_NONE &&
+			     notification->sigev_notify != SIGEV_SIGNAL &&
+			     notification->sigev_notify != SIGEV_THREAD))
+			return -EINVAL;
+		if (notification->sigev_notify == SIGEV_SIGNAL &&
+			!valid_signal(notification->sigev_signo)) {
+			return -EINVAL;
+		}
+		if (notification->sigev_notify == SIGEV_THREAD) {
+			long timeo;
+
+			/* create the notify skb */
+			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
+			if (!nc) {
+				ret = -ENOMEM;
+				goto out;
+			}
+			if (copy_from_user(nc->data,
+					notification->sigev_value.sival_ptr,
+					NOTIFY_COOKIE_LEN)) {
+				ret = -EFAULT;
+				goto out;
+			}
+
+			/* TODO: add a header? */
+			skb_put(nc, NOTIFY_COOKIE_LEN);
+			/* and attach it to the socket */
+retry:
+			f = fdget(notification->sigev_signo);
+			if (!f.file) {
+				ret = -EBADF;
+				goto out;
+			}
+			sock = netlink_getsockbyfilp(f.file);
+			fdput(f);
+			if (IS_ERR(sock)) {
+				ret = PTR_ERR(sock);
+				sock = NULL;
+				goto out;
+			}
+
+			timeo = MAX_SCHEDULE_TIMEOUT;
+			ret = netlink_attachskb(sock, nc, &timeo, NULL);
+			if (ret == 1) {
+				sock = NULL;
+				goto retry;
+			}
+			if (ret) {
+				sock = NULL;
+				nc = NULL;
+				goto out;
+			}
+		}
+	}
+
+	f = fdget(mqdes);
+	if (!f.file) {
+		ret = -EBADF;
+		goto out;
+	}
+
+	inode = file_inode(f.file);
+	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
+		ret = -EBADF;
+		goto out_fput;
+	}
+	info = MQUEUE_I(inode);
+
+	ret = 0;
+	spin_lock(&info->lock);
+	if (notification == NULL) {
+		if (info->notify_owner == task_tgid(current)) {
+			remove_notification(info);
+			inode->i_atime = inode->i_ctime = current_time(inode);
+		}
+	} else if (info->notify_owner != NULL) {
+		ret = -EBUSY;
+	} else {
+		switch (notification->sigev_notify) {
+		case SIGEV_NONE:
+			info->notify.sigev_notify = SIGEV_NONE;
+			break;
+		case SIGEV_THREAD:
+			info->notify_sock = sock;
+			info->notify_cookie = nc;
+			sock = NULL;
+			nc = NULL;
+			info->notify.sigev_notify = SIGEV_THREAD;
+			break;
+		case SIGEV_SIGNAL:
+			info->notify.sigev_signo = notification->sigev_signo;
+			info->notify.sigev_value = notification->sigev_value;
+			info->notify.sigev_notify = SIGEV_SIGNAL;
+			info->notify_self_exec_id = current->self_exec_id;
+			break;
+		}
+
+		info->notify_owner = get_pid(task_tgid(current));
+		info->notify_user_ns = get_user_ns(current_user_ns());
+		inode->i_atime = inode->i_ctime = current_time(inode);
+	}
+	spin_unlock(&info->lock);
+out_fput:
+	fdput(f);
+out:
+	if (sock)
+		netlink_detachskb(sock, nc);
+	else if (nc)
+		dev_kfree_skb(nc);
+
+	return ret;
+}
+
+SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
+		const struct sigevent __user *, u_notification)
+{
+	struct sigevent n, *p = NULL;
+	if (u_notification) {
+		if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
+			return -EFAULT;
+		p = &n;
+	}
+	return do_mq_notify(mqdes, p);
+}
+
+static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
+{
+	struct fd f;
+	struct inode *inode;
+	struct mqueue_inode_info *info;
+
+	if (new && (new->mq_flags & (~O_NONBLOCK)))
+		return -EINVAL;
+
+	f = fdget(mqdes);
+	if (!f.file)
+		return -EBADF;
+
+	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
+		fdput(f);
+		return -EBADF;
+	}
+
+	inode = file_inode(f.file);
+	info = MQUEUE_I(inode);
+
+	spin_lock(&info->lock);
+
+	if (old) {
+		*old = info->attr;
+		old->mq_flags = f.file->f_flags & O_NONBLOCK;
+	}
+	if (new) {
+		audit_mq_getsetattr(mqdes, new);
+		spin_lock(&f.file->f_lock);
+		if (new->mq_flags & O_NONBLOCK)
+			f.file->f_flags |= O_NONBLOCK;
+		else
+			f.file->f_flags &= ~O_NONBLOCK;
+		spin_unlock(&f.file->f_lock);
+
+		inode->i_atime = inode->i_ctime = current_time(inode);
+	}
+
+	spin_unlock(&info->lock);
+	fdput(f);
+	return 0;
+}
+
+SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
+		const struct mq_attr __user *, u_mqstat,
+		struct mq_attr __user *, u_omqstat)
+{
+	int ret;
+	struct mq_attr mqstat, omqstat;
+	struct mq_attr *new = NULL, *old = NULL;
+
+	if (u_mqstat) {
+		new = &mqstat;
+		if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
+			return -EFAULT;
+	}
+	if (u_omqstat)
+		old = &omqstat;
+
+	ret = do_mq_getsetattr(mqdes, new, old);
+	if (ret || !old)
+		return ret;
+
+	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
+		return -EFAULT;
+	return 0;
+}
+
+#ifdef CONFIG_COMPAT
+
+struct compat_mq_attr {
+	compat_long_t mq_flags;      /* message queue flags		     */
+	compat_long_t mq_maxmsg;     /* maximum number of messages	     */
+	compat_long_t mq_msgsize;    /* maximum message size		     */
+	compat_long_t mq_curmsgs;    /* number of messages currently queued  */
+	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
+};
+
+static inline int get_compat_mq_attr(struct mq_attr *attr,
+			const struct compat_mq_attr __user *uattr)
+{
+	struct compat_mq_attr v;
+
+	if (copy_from_user(&v, uattr, sizeof(*uattr)))
+		return -EFAULT;
+
+	memset(attr, 0, sizeof(*attr));
+	attr->mq_flags = v.mq_flags;
+	attr->mq_maxmsg = v.mq_maxmsg;
+	attr->mq_msgsize = v.mq_msgsize;
+	attr->mq_curmsgs = v.mq_curmsgs;
+	return 0;
+}
+
+static inline int put_compat_mq_attr(const struct mq_attr *attr,
+			struct compat_mq_attr __user *uattr)
+{
+	struct compat_mq_attr v;
+
+	memset(&v, 0, sizeof(v));
+	v.mq_flags = attr->mq_flags;
+	v.mq_maxmsg = attr->mq_maxmsg;
+	v.mq_msgsize = attr->mq_msgsize;
+	v.mq_curmsgs = attr->mq_curmsgs;
+	if (copy_to_user(uattr, &v, sizeof(*uattr)))
+		return -EFAULT;
+	return 0;
+}
+
+COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
+		       int, oflag, compat_mode_t, mode,
+		       struct compat_mq_attr __user *, u_attr)
+{
+	struct mq_attr attr, *p = NULL;
+	if (u_attr && oflag & O_CREAT) {
+		p = &attr;
+		if (get_compat_mq_attr(&attr, u_attr))
+			return -EFAULT;
+	}
+	return do_mq_open(u_name, oflag, mode, p);
+}
+
+COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
+		       const struct compat_sigevent __user *, u_notification)
+{
+	struct sigevent n, *p = NULL;
+	if (u_notification) {
+		if (get_compat_sigevent(&n, u_notification))
+			return -EFAULT;
+		if (n.sigev_notify == SIGEV_THREAD)
+			n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
+		p = &n;
+	}
+	return do_mq_notify(mqdes, p);
+}
+
+COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
+		       const struct compat_mq_attr __user *, u_mqstat,
+		       struct compat_mq_attr __user *, u_omqstat)
+{
+	int ret;
+	struct mq_attr mqstat, omqstat;
+	struct mq_attr *new = NULL, *old = NULL;
+
+	if (u_mqstat) {
+		new = &mqstat;
+		if (get_compat_mq_attr(new, u_mqstat))
+			return -EFAULT;
+	}
+	if (u_omqstat)
+		old = &omqstat;
+
+	ret = do_mq_getsetattr(mqdes, new, old);
+	if (ret || !old)
+		return ret;
+
+	if (put_compat_mq_attr(old, u_omqstat))
+		return -EFAULT;
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_COMPAT_32BIT_TIME
+static int compat_prepare_timeout(const struct compat_timespec __user *p,
+				   struct timespec64 *ts)
+{
+	if (compat_get_timespec64(ts, p))
+		return -EFAULT;
+	if (!timespec64_valid(ts))
+		return -EINVAL;
+	return 0;
+}
+
+COMPAT_SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes,
+		       const char __user *, u_msg_ptr,
+		       compat_size_t, msg_len, unsigned int, msg_prio,
+		       const struct compat_timespec __user *, u_abs_timeout)
+{
+	struct timespec64 ts, *p = NULL;
+	if (u_abs_timeout) {
+		int res = compat_prepare_timeout(u_abs_timeout, &ts);
+		if (res)
+			return res;
+		p = &ts;
+	}
+	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
+}
+
+COMPAT_SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes,
+		       char __user *, u_msg_ptr,
+		       compat_size_t, msg_len, unsigned int __user *, u_msg_prio,
+		       const struct compat_timespec __user *, u_abs_timeout)
+{
+	struct timespec64 ts, *p = NULL;
+	if (u_abs_timeout) {
+		int res = compat_prepare_timeout(u_abs_timeout, &ts);
+		if (res)
+			return res;
+		p = &ts;
+	}
+	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
+}
+#endif
+
+static const struct inode_operations mqueue_dir_inode_operations = {
+	.lookup = simple_lookup,
+	.create = mqueue_create,
+	.unlink = mqueue_unlink,
+};
+
+static const struct file_operations mqueue_file_operations = {
+	.flush = mqueue_flush_file,
+	.poll = mqueue_poll_file,
+	.read = mqueue_read_file,
+	.llseek = default_llseek,
+};
+
+static const struct super_operations mqueue_super_ops = {
+	.alloc_inode = mqueue_alloc_inode,
+	.destroy_inode = mqueue_destroy_inode,
+	.evict_inode = mqueue_evict_inode,
+	.statfs = simple_statfs,
+};
+
+static struct file_system_type mqueue_fs_type = {
+	.name = "mqueue",
+	.mount = mqueue_mount,
+	.kill_sb = kill_litter_super,
+	.fs_flags = FS_USERNS_MOUNT,
+};
+
+int mq_init_ns(struct ipc_namespace *ns)
+{
+	ns->mq_queues_count  = 0;
+	ns->mq_queues_max    = DFLT_QUEUESMAX;
+	ns->mq_msg_max       = DFLT_MSGMAX;
+	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
+	ns->mq_msg_default   = DFLT_MSG;
+	ns->mq_msgsize_default  = DFLT_MSGSIZE;
+
+	ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
+	if (IS_ERR(ns->mq_mnt)) {
+		int err = PTR_ERR(ns->mq_mnt);
+		ns->mq_mnt = NULL;
+		return err;
+	}
+	return 0;
+}
+
+void mq_clear_sbinfo(struct ipc_namespace *ns)
+{
+	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
+}
+
+void mq_put_mnt(struct ipc_namespace *ns)
+{
+	kern_unmount(ns->mq_mnt);
+}
+
+static int __init init_mqueue_fs(void)
+{
+	int error;
+
+	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
+				sizeof(struct mqueue_inode_info), 0,
+				SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once);
+	if (mqueue_inode_cachep == NULL)
+		return -ENOMEM;
+
+	/* ignore failures - they are not fatal */
+	mq_sysctl_table = mq_register_sysctl_table();
+
+	error = register_filesystem(&mqueue_fs_type);
+	if (error)
+		goto out_sysctl;
+
+	spin_lock_init(&mq_lock);
+
+	error = mq_init_ns(&init_ipc_ns);
+	if (error)
+		goto out_filesystem;
+
+	return 0;
+
+out_filesystem:
+	unregister_filesystem(&mqueue_fs_type);
+out_sysctl:
+	if (mq_sysctl_table)
+		unregister_sysctl_table(mq_sysctl_table);
+	kmem_cache_destroy(mqueue_inode_cachep);
+	return error;
+}
+
+device_initcall(init_mqueue_fs);