xref: /linux/ipc/mqueue.c (revision b5f20061)
1 /*
2  * POSIX message queues filesystem for Linux.
3  *
4  * Copyright (C) 2003,2004  Krzysztof Benedyczak    (golbi@mat.uni.torun.pl)
5  *                          Michal Wronski          (michal.wronski@gmail.com)
6  *
7  * Spinlocks:               Mohamed Abbas           (abbas.mohamed@intel.com)
8  * Lockless receive & send, fd based notify:
9  *			    Manfred Spraul	    (manfred@colorfullife.com)
10  *
11  * Audit:                   George Wilson           (ltcgcw@us.ibm.com)
12  *
13  * This file is released under the GPL.
14  */
15 
16 #include <linux/capability.h>
17 #include <linux/init.h>
18 #include <linux/pagemap.h>
19 #include <linux/file.h>
20 #include <linux/mount.h>
21 #include <linux/fs_context.h>
22 #include <linux/namei.h>
23 #include <linux/sysctl.h>
24 #include <linux/poll.h>
25 #include <linux/mqueue.h>
26 #include <linux/msg.h>
27 #include <linux/skbuff.h>
28 #include <linux/vmalloc.h>
29 #include <linux/netlink.h>
30 #include <linux/syscalls.h>
31 #include <linux/audit.h>
32 #include <linux/signal.h>
33 #include <linux/mutex.h>
34 #include <linux/nsproxy.h>
35 #include <linux/pid.h>
36 #include <linux/ipc_namespace.h>
37 #include <linux/user_namespace.h>
38 #include <linux/slab.h>
39 #include <linux/sched/wake_q.h>
40 #include <linux/sched/signal.h>
41 #include <linux/sched/user.h>
42 
43 #include <net/sock.h>
44 #include "util.h"
45 
46 struct mqueue_fs_context {
47 	struct ipc_namespace	*ipc_ns;
48 };
49 
50 #define MQUEUE_MAGIC	0x19800202
51 #define DIRENT_SIZE	20
52 #define FILENT_SIZE	80
53 
54 #define SEND		0
55 #define RECV		1
56 
57 #define STATE_NONE	0
58 #define STATE_READY	1
59 
60 struct posix_msg_tree_node {
61 	struct rb_node		rb_node;
62 	struct list_head	msg_list;
63 	int			priority;
64 };
65 
66 /*
67  * Locking:
68  *
69  * Accesses to a message queue are synchronized by acquiring info->lock.
70  *
71  * There are two notable exceptions:
72  * - The actual wakeup of a sleeping task is performed using the wake_q
73  *   framework. info->lock is already released when wake_up_q is called.
74  * - The exit codepaths after sleeping check ext_wait_queue->state without
75  *   any locks. If it is STATE_READY, then the syscall is completed without
76  *   acquiring info->lock.
77  *
78  * MQ_BARRIER:
79  * To achieve proper release/acquire memory barrier pairing, the state is set to
80  * STATE_READY with smp_store_release(), and it is read with READ_ONCE followed
81  * by smp_acquire__after_ctrl_dep(). In addition, wake_q_add_safe() is used.
82  *
83  * This prevents the following races:
84  *
85  * 1) With the simple wake_q_add(), the task could be gone already before
86  *    the increase of the reference happens
87  * Thread A
88  *				Thread B
89  * WRITE_ONCE(wait.state, STATE_NONE);
90  * schedule_hrtimeout()
91  *				wake_q_add(A)
92  *				if (cmpxchg()) // success
93  *				   ->state = STATE_READY (reordered)
94  * <timeout returns>
95  * if (wait.state == STATE_READY) return;
96  * sysret to user space
97  * sys_exit()
98  *				get_task_struct() // UaF
99  *
100  * Solution: Use wake_q_add_safe() and perform the get_task_struct() before
101  * the smp_store_release() that does ->state = STATE_READY.
102  *
103  * 2) Without proper _release/_acquire barriers, the woken up task
104  *    could read stale data
105  *
106  * Thread A
107  *				Thread B
108  * do_mq_timedreceive
109  * WRITE_ONCE(wait.state, STATE_NONE);
110  * schedule_hrtimeout()
111  *				state = STATE_READY;
112  * <timeout returns>
113  * if (wait.state == STATE_READY) return;
114  * msg_ptr = wait.msg;		// Access to stale data!
115  *				receiver->msg = message; (reordered)
116  *
117  * Solution: use _release and _acquire barriers.
118  *
119  * 3) There is intentionally no barrier when setting current->state
120  *    to TASK_INTERRUPTIBLE: spin_unlock(&info->lock) provides the
121  *    release memory barrier, and the wakeup is triggered when holding
122  *    info->lock, i.e. spin_lock(&info->lock) provided a pairing
123  *    acquire memory barrier.
124  */
125 
126 struct ext_wait_queue {		/* queue of sleeping tasks */
127 	struct task_struct *task;
128 	struct list_head list;
129 	struct msg_msg *msg;	/* ptr of loaded message */
130 	int state;		/* one of STATE_* values */
131 };
132 
133 struct mqueue_inode_info {
134 	spinlock_t lock;
135 	struct inode vfs_inode;
136 	wait_queue_head_t wait_q;
137 
138 	struct rb_root msg_tree;
139 	struct rb_node *msg_tree_rightmost;
140 	struct posix_msg_tree_node *node_cache;
141 	struct mq_attr attr;
142 
143 	struct sigevent notify;
144 	struct pid *notify_owner;
145 	u32 notify_self_exec_id;
146 	struct user_namespace *notify_user_ns;
147 	struct user_struct *user;	/* user who created, for accounting */
148 	struct sock *notify_sock;
149 	struct sk_buff *notify_cookie;
150 
151 	/* for tasks waiting for free space and messages, respectively */
152 	struct ext_wait_queue e_wait_q[2];
153 
154 	unsigned long qsize; /* size of queue in memory (sum of all msgs) */
155 };
156 
157 static struct file_system_type mqueue_fs_type;
158 static const struct inode_operations mqueue_dir_inode_operations;
159 static const struct file_operations mqueue_file_operations;
160 static const struct super_operations mqueue_super_ops;
161 static const struct fs_context_operations mqueue_fs_context_ops;
162 static void remove_notification(struct mqueue_inode_info *info);
163 
164 static struct kmem_cache *mqueue_inode_cachep;
165 
166 static struct ctl_table_header *mq_sysctl_table;
167 
MQUEUE_I(struct inode * inode)168 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
169 {
170 	return container_of(inode, struct mqueue_inode_info, vfs_inode);
171 }
172 
173 /*
174  * This routine should be called with the mq_lock held.
175  */
__get_ns_from_inode(struct inode * inode)176 static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
177 {
178 	return get_ipc_ns(inode->i_sb->s_fs_info);
179 }
180 
get_ns_from_inode(struct inode * inode)181 static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
182 {
183 	struct ipc_namespace *ns;
184 
185 	spin_lock(&mq_lock);
186 	ns = __get_ns_from_inode(inode);
187 	spin_unlock(&mq_lock);
188 	return ns;
189 }
190 
191 /* Auxiliary functions to manipulate messages' list */
msg_insert(struct msg_msg * msg,struct mqueue_inode_info * info)192 static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
193 {
194 	struct rb_node **p, *parent = NULL;
195 	struct posix_msg_tree_node *leaf;
196 	bool rightmost = true;
197 
198 	p = &info->msg_tree.rb_node;
199 	while (*p) {
200 		parent = *p;
201 		leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
202 
203 		if (likely(leaf->priority == msg->m_type))
204 			goto insert_msg;
205 		else if (msg->m_type < leaf->priority) {
206 			p = &(*p)->rb_left;
207 			rightmost = false;
208 		} else
209 			p = &(*p)->rb_right;
210 	}
211 	if (info->node_cache) {
212 		leaf = info->node_cache;
213 		info->node_cache = NULL;
214 	} else {
215 		leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
216 		if (!leaf)
217 			return -ENOMEM;
218 		INIT_LIST_HEAD(&leaf->msg_list);
219 	}
220 	leaf->priority = msg->m_type;
221 
222 	if (rightmost)
223 		info->msg_tree_rightmost = &leaf->rb_node;
224 
225 	rb_link_node(&leaf->rb_node, parent, p);
226 	rb_insert_color(&leaf->rb_node, &info->msg_tree);
227 insert_msg:
228 	info->attr.mq_curmsgs++;
229 	info->qsize += msg->m_ts;
230 	list_add_tail(&msg->m_list, &leaf->msg_list);
231 	return 0;
232 }
233 
msg_tree_erase(struct posix_msg_tree_node * leaf,struct mqueue_inode_info * info)234 static inline void msg_tree_erase(struct posix_msg_tree_node *leaf,
235 				  struct mqueue_inode_info *info)
236 {
237 	struct rb_node *node = &leaf->rb_node;
238 
239 	if (info->msg_tree_rightmost == node)
240 		info->msg_tree_rightmost = rb_prev(node);
241 
242 	rb_erase(node, &info->msg_tree);
243 	if (info->node_cache)
244 		kfree(leaf);
245 	else
246 		info->node_cache = leaf;
247 }
248 
msg_get(struct mqueue_inode_info * info)249 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
250 {
251 	struct rb_node *parent = NULL;
252 	struct posix_msg_tree_node *leaf;
253 	struct msg_msg *msg;
254 
255 try_again:
256 	/*
257 	 * During insert, low priorities go to the left and high to the
258 	 * right.  On receive, we want the highest priorities first, so
259 	 * walk all the way to the right.
260 	 */
261 	parent = info->msg_tree_rightmost;
262 	if (!parent) {
263 		if (info->attr.mq_curmsgs) {
264 			pr_warn_once("Inconsistency in POSIX message queue, "
265 				     "no tree element, but supposedly messages "
266 				     "should exist!\n");
267 			info->attr.mq_curmsgs = 0;
268 		}
269 		return NULL;
270 	}
271 	leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
272 	if (unlikely(list_empty(&leaf->msg_list))) {
273 		pr_warn_once("Inconsistency in POSIX message queue, "
274 			     "empty leaf node but we haven't implemented "
275 			     "lazy leaf delete!\n");
276 		msg_tree_erase(leaf, info);
277 		goto try_again;
278 	} else {
279 		msg = list_first_entry(&leaf->msg_list,
280 				       struct msg_msg, m_list);
281 		list_del(&msg->m_list);
282 		if (list_empty(&leaf->msg_list)) {
283 			msg_tree_erase(leaf, info);
284 		}
285 	}
286 	info->attr.mq_curmsgs--;
287 	info->qsize -= msg->m_ts;
288 	return msg;
289 }
290 
mqueue_get_inode(struct super_block * sb,struct ipc_namespace * ipc_ns,umode_t mode,struct mq_attr * attr)291 static struct inode *mqueue_get_inode(struct super_block *sb,
292 		struct ipc_namespace *ipc_ns, umode_t mode,
293 		struct mq_attr *attr)
294 {
295 	struct user_struct *u = current_user();
296 	struct inode *inode;
297 	int ret = -ENOMEM;
298 
299 	inode = new_inode(sb);
300 	if (!inode)
301 		goto err;
302 
303 	inode->i_ino = get_next_ino();
304 	inode->i_mode = mode;
305 	inode->i_uid = current_fsuid();
306 	inode->i_gid = current_fsgid();
307 	inode->i_mtime = inode->i_ctime = inode->i_atime = current_time(inode);
308 
309 	if (S_ISREG(mode)) {
310 		struct mqueue_inode_info *info;
311 		unsigned long mq_bytes, mq_treesize;
312 
313 		inode->i_fop = &mqueue_file_operations;
314 		inode->i_size = FILENT_SIZE;
315 		/* mqueue specific info */
316 		info = MQUEUE_I(inode);
317 		spin_lock_init(&info->lock);
318 		init_waitqueue_head(&info->wait_q);
319 		INIT_LIST_HEAD(&info->e_wait_q[0].list);
320 		INIT_LIST_HEAD(&info->e_wait_q[1].list);
321 		info->notify_owner = NULL;
322 		info->notify_user_ns = NULL;
323 		info->qsize = 0;
324 		info->user = NULL;	/* set when all is ok */
325 		info->msg_tree = RB_ROOT;
326 		info->msg_tree_rightmost = NULL;
327 		info->node_cache = NULL;
328 		memset(&info->attr, 0, sizeof(info->attr));
329 		info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
330 					   ipc_ns->mq_msg_default);
331 		info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
332 					    ipc_ns->mq_msgsize_default);
333 		if (attr) {
334 			info->attr.mq_maxmsg = attr->mq_maxmsg;
335 			info->attr.mq_msgsize = attr->mq_msgsize;
336 		}
337 		/*
338 		 * We used to allocate a static array of pointers and account
339 		 * the size of that array as well as one msg_msg struct per
340 		 * possible message into the queue size. That's no longer
341 		 * accurate as the queue is now an rbtree and will grow and
342 		 * shrink depending on usage patterns.  We can, however, still
343 		 * account one msg_msg struct per message, but the nodes are
344 		 * allocated depending on priority usage, and most programs
345 		 * only use one, or a handful, of priorities.  However, since
346 		 * this is pinned memory, we need to assume worst case, so
347 		 * that means the min(mq_maxmsg, max_priorities) * struct
348 		 * posix_msg_tree_node.
349 		 */
350 
351 		ret = -EINVAL;
352 		if (info->attr.mq_maxmsg <= 0 || info->attr.mq_msgsize <= 0)
353 			goto out_inode;
354 		if (capable(CAP_SYS_RESOURCE)) {
355 			if (info->attr.mq_maxmsg > HARD_MSGMAX ||
356 			    info->attr.mq_msgsize > HARD_MSGSIZEMAX)
357 				goto out_inode;
358 		} else {
359 			if (info->attr.mq_maxmsg > ipc_ns->mq_msg_max ||
360 					info->attr.mq_msgsize > ipc_ns->mq_msgsize_max)
361 				goto out_inode;
362 		}
363 		ret = -EOVERFLOW;
364 		/* check for overflow */
365 		if (info->attr.mq_msgsize > ULONG_MAX/info->attr.mq_maxmsg)
366 			goto out_inode;
367 		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
368 			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
369 			sizeof(struct posix_msg_tree_node);
370 		mq_bytes = info->attr.mq_maxmsg * info->attr.mq_msgsize;
371 		if (mq_bytes + mq_treesize < mq_bytes)
372 			goto out_inode;
373 		mq_bytes += mq_treesize;
374 		spin_lock(&mq_lock);
375 		if (u->mq_bytes + mq_bytes < u->mq_bytes ||
376 		    u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
377 			spin_unlock(&mq_lock);
378 			/* mqueue_evict_inode() releases info->messages */
379 			ret = -EMFILE;
380 			goto out_inode;
381 		}
382 		u->mq_bytes += mq_bytes;
383 		spin_unlock(&mq_lock);
384 
385 		/* all is ok */
386 		info->user = get_uid(u);
387 	} else if (S_ISDIR(mode)) {
388 		inc_nlink(inode);
389 		/* Some things misbehave if size == 0 on a directory */
390 		inode->i_size = 2 * DIRENT_SIZE;
391 		inode->i_op = &mqueue_dir_inode_operations;
392 		inode->i_fop = &simple_dir_operations;
393 	}
394 
395 	return inode;
396 out_inode:
397 	iput(inode);
398 err:
399 	return ERR_PTR(ret);
400 }
401 
mqueue_fill_super(struct super_block * sb,struct fs_context * fc)402 static int mqueue_fill_super(struct super_block *sb, struct fs_context *fc)
403 {
404 	struct inode *inode;
405 	struct ipc_namespace *ns = sb->s_fs_info;
406 
407 	sb->s_iflags |= SB_I_NOEXEC | SB_I_NODEV;
408 	sb->s_blocksize = PAGE_SIZE;
409 	sb->s_blocksize_bits = PAGE_SHIFT;
410 	sb->s_magic = MQUEUE_MAGIC;
411 	sb->s_op = &mqueue_super_ops;
412 
413 	inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
414 	if (IS_ERR(inode))
415 		return PTR_ERR(inode);
416 
417 	sb->s_root = d_make_root(inode);
418 	if (!sb->s_root)
419 		return -ENOMEM;
420 	return 0;
421 }
422 
mqueue_get_tree(struct fs_context * fc)423 static int mqueue_get_tree(struct fs_context *fc)
424 {
425 	struct mqueue_fs_context *ctx = fc->fs_private;
426 
427 	return get_tree_keyed(fc, mqueue_fill_super, ctx->ipc_ns);
428 }
429 
mqueue_fs_context_free(struct fs_context * fc)430 static void mqueue_fs_context_free(struct fs_context *fc)
431 {
432 	struct mqueue_fs_context *ctx = fc->fs_private;
433 
434 	put_ipc_ns(ctx->ipc_ns);
435 	kfree(ctx);
436 }
437 
mqueue_init_fs_context(struct fs_context * fc)438 static int mqueue_init_fs_context(struct fs_context *fc)
439 {
440 	struct mqueue_fs_context *ctx;
441 
442 	ctx = kzalloc(sizeof(struct mqueue_fs_context), GFP_KERNEL);
443 	if (!ctx)
444 		return -ENOMEM;
445 
446 	ctx->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
447 	put_user_ns(fc->user_ns);
448 	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
449 	fc->fs_private = ctx;
450 	fc->ops = &mqueue_fs_context_ops;
451 	return 0;
452 }
453 
mq_create_mount(struct ipc_namespace * ns)454 static struct vfsmount *mq_create_mount(struct ipc_namespace *ns)
455 {
456 	struct mqueue_fs_context *ctx;
457 	struct fs_context *fc;
458 	struct vfsmount *mnt;
459 
460 	fc = fs_context_for_mount(&mqueue_fs_type, SB_KERNMOUNT);
461 	if (IS_ERR(fc))
462 		return ERR_CAST(fc);
463 
464 	ctx = fc->fs_private;
465 	put_ipc_ns(ctx->ipc_ns);
466 	ctx->ipc_ns = get_ipc_ns(ns);
467 	put_user_ns(fc->user_ns);
468 	fc->user_ns = get_user_ns(ctx->ipc_ns->user_ns);
469 
470 	mnt = fc_mount(fc);
471 	put_fs_context(fc);
472 	return mnt;
473 }
474 
init_once(void * foo)475 static void init_once(void *foo)
476 {
477 	struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
478 
479 	inode_init_once(&p->vfs_inode);
480 }
481 
mqueue_alloc_inode(struct super_block * sb)482 static struct inode *mqueue_alloc_inode(struct super_block *sb)
483 {
484 	struct mqueue_inode_info *ei;
485 
486 	ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
487 	if (!ei)
488 		return NULL;
489 	return &ei->vfs_inode;
490 }
491 
mqueue_free_inode(struct inode * inode)492 static void mqueue_free_inode(struct inode *inode)
493 {
494 	kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
495 }
496 
mqueue_evict_inode(struct inode * inode)497 static void mqueue_evict_inode(struct inode *inode)
498 {
499 	struct mqueue_inode_info *info;
500 	struct user_struct *user;
501 	struct ipc_namespace *ipc_ns;
502 	struct msg_msg *msg, *nmsg;
503 	LIST_HEAD(tmp_msg);
504 
505 	clear_inode(inode);
506 
507 	if (S_ISDIR(inode->i_mode))
508 		return;
509 
510 	ipc_ns = get_ns_from_inode(inode);
511 	info = MQUEUE_I(inode);
512 	spin_lock(&info->lock);
513 	while ((msg = msg_get(info)) != NULL)
514 		list_add_tail(&msg->m_list, &tmp_msg);
515 	kfree(info->node_cache);
516 	spin_unlock(&info->lock);
517 
518 	list_for_each_entry_safe(msg, nmsg, &tmp_msg, m_list) {
519 		list_del(&msg->m_list);
520 		free_msg(msg);
521 	}
522 
523 	user = info->user;
524 	if (user) {
525 		unsigned long mq_bytes, mq_treesize;
526 
527 		/* Total amount of bytes accounted for the mqueue */
528 		mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
529 			min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
530 			sizeof(struct posix_msg_tree_node);
531 
532 		mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
533 					  info->attr.mq_msgsize);
534 
535 		spin_lock(&mq_lock);
536 		user->mq_bytes -= mq_bytes;
537 		/*
538 		 * get_ns_from_inode() ensures that the
539 		 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
540 		 * to which we now hold a reference, or it is NULL.
541 		 * We can't put it here under mq_lock, though.
542 		 */
543 		if (ipc_ns)
544 			ipc_ns->mq_queues_count--;
545 		spin_unlock(&mq_lock);
546 		free_uid(user);
547 	}
548 	if (ipc_ns)
549 		put_ipc_ns(ipc_ns);
550 }
551 
mqueue_create_attr(struct dentry * dentry,umode_t mode,void * arg)552 static int mqueue_create_attr(struct dentry *dentry, umode_t mode, void *arg)
553 {
554 	struct inode *dir = dentry->d_parent->d_inode;
555 	struct inode *inode;
556 	struct mq_attr *attr = arg;
557 	int error;
558 	struct ipc_namespace *ipc_ns;
559 
560 	spin_lock(&mq_lock);
561 	ipc_ns = __get_ns_from_inode(dir);
562 	if (!ipc_ns) {
563 		error = -EACCES;
564 		goto out_unlock;
565 	}
566 
567 	if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
568 	    !capable(CAP_SYS_RESOURCE)) {
569 		error = -ENOSPC;
570 		goto out_unlock;
571 	}
572 	ipc_ns->mq_queues_count++;
573 	spin_unlock(&mq_lock);
574 
575 	inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
576 	if (IS_ERR(inode)) {
577 		error = PTR_ERR(inode);
578 		spin_lock(&mq_lock);
579 		ipc_ns->mq_queues_count--;
580 		goto out_unlock;
581 	}
582 
583 	put_ipc_ns(ipc_ns);
584 	dir->i_size += DIRENT_SIZE;
585 	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
586 
587 	d_instantiate(dentry, inode);
588 	dget(dentry);
589 	return 0;
590 out_unlock:
591 	spin_unlock(&mq_lock);
592 	if (ipc_ns)
593 		put_ipc_ns(ipc_ns);
594 	return error;
595 }
596 
mqueue_create(struct inode * dir,struct dentry * dentry,umode_t mode,bool excl)597 static int mqueue_create(struct inode *dir, struct dentry *dentry,
598 				umode_t mode, bool excl)
599 {
600 	return mqueue_create_attr(dentry, mode, NULL);
601 }
602 
mqueue_unlink(struct inode * dir,struct dentry * dentry)603 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
604 {
605 	struct inode *inode = d_inode(dentry);
606 
607 	dir->i_ctime = dir->i_mtime = dir->i_atime = current_time(dir);
608 	dir->i_size -= DIRENT_SIZE;
609 	drop_nlink(inode);
610 	dput(dentry);
611 	return 0;
612 }
613 
614 /*
615 *	This is routine for system read from queue file.
616 *	To avoid mess with doing here some sort of mq_receive we allow
617 *	to read only queue size & notification info (the only values
618 *	that are interesting from user point of view and aren't accessible
619 *	through std routines)
620 */
mqueue_read_file(struct file * filp,char __user * u_data,size_t count,loff_t * off)621 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
622 				size_t count, loff_t *off)
623 {
624 	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
625 	char buffer[FILENT_SIZE];
626 	ssize_t ret;
627 
628 	spin_lock(&info->lock);
629 	snprintf(buffer, sizeof(buffer),
630 			"QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
631 			info->qsize,
632 			info->notify_owner ? info->notify.sigev_notify : 0,
633 			(info->notify_owner &&
634 			 info->notify.sigev_notify == SIGEV_SIGNAL) ?
635 				info->notify.sigev_signo : 0,
636 			pid_vnr(info->notify_owner));
637 	spin_unlock(&info->lock);
638 	buffer[sizeof(buffer)-1] = '\0';
639 
640 	ret = simple_read_from_buffer(u_data, count, off, buffer,
641 				strlen(buffer));
642 	if (ret <= 0)
643 		return ret;
644 
645 	file_inode(filp)->i_atime = file_inode(filp)->i_ctime = current_time(file_inode(filp));
646 	return ret;
647 }
648 
mqueue_flush_file(struct file * filp,fl_owner_t id)649 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
650 {
651 	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
652 
653 	spin_lock(&info->lock);
654 	if (task_tgid(current) == info->notify_owner)
655 		remove_notification(info);
656 
657 	spin_unlock(&info->lock);
658 	return 0;
659 }
660 
mqueue_poll_file(struct file * filp,struct poll_table_struct * poll_tab)661 static __poll_t mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
662 {
663 	struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
664 	__poll_t retval = 0;
665 
666 	poll_wait(filp, &info->wait_q, poll_tab);
667 
668 	spin_lock(&info->lock);
669 	if (info->attr.mq_curmsgs)
670 		retval = EPOLLIN | EPOLLRDNORM;
671 
672 	if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
673 		retval |= EPOLLOUT | EPOLLWRNORM;
674 	spin_unlock(&info->lock);
675 
676 	return retval;
677 }
678 
679 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
wq_add(struct mqueue_inode_info * info,int sr,struct ext_wait_queue * ewp)680 static void wq_add(struct mqueue_inode_info *info, int sr,
681 			struct ext_wait_queue *ewp)
682 {
683 	struct ext_wait_queue *walk;
684 
685 	list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
686 		if (walk->task->prio <= current->prio) {
687 			list_add_tail(&ewp->list, &walk->list);
688 			return;
689 		}
690 	}
691 	list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
692 }
693 
694 /*
695  * Puts current task to sleep. Caller must hold queue lock. After return
696  * lock isn't held.
697  * sr: SEND or RECV
698  */
wq_sleep(struct mqueue_inode_info * info,int sr,ktime_t * timeout,struct ext_wait_queue * ewp)699 static int wq_sleep(struct mqueue_inode_info *info, int sr,
700 		    ktime_t *timeout, struct ext_wait_queue *ewp)
701 	__releases(&info->lock)
702 {
703 	int retval;
704 	signed long time;
705 
706 	wq_add(info, sr, ewp);
707 
708 	for (;;) {
709 		/* memory barrier not required, we hold info->lock */
710 		__set_current_state(TASK_INTERRUPTIBLE);
711 
712 		spin_unlock(&info->lock);
713 		time = schedule_hrtimeout_range_clock(timeout, 0,
714 			HRTIMER_MODE_ABS, CLOCK_REALTIME);
715 
716 		if (READ_ONCE(ewp->state) == STATE_READY) {
717 			/* see MQ_BARRIER for purpose/pairing */
718 			smp_acquire__after_ctrl_dep();
719 			retval = 0;
720 			goto out;
721 		}
722 		spin_lock(&info->lock);
723 
724 		/* we hold info->lock, so no memory barrier required */
725 		if (READ_ONCE(ewp->state) == STATE_READY) {
726 			retval = 0;
727 			goto out_unlock;
728 		}
729 		if (signal_pending(current)) {
730 			retval = -ERESTARTSYS;
731 			break;
732 		}
733 		if (time == 0) {
734 			retval = -ETIMEDOUT;
735 			break;
736 		}
737 	}
738 	list_del(&ewp->list);
739 out_unlock:
740 	spin_unlock(&info->lock);
741 out:
742 	return retval;
743 }
744 
745 /*
746  * Returns waiting task that should be serviced first or NULL if none exists
747  */
wq_get_first_waiter(struct mqueue_inode_info * info,int sr)748 static struct ext_wait_queue *wq_get_first_waiter(
749 		struct mqueue_inode_info *info, int sr)
750 {
751 	struct list_head *ptr;
752 
753 	ptr = info->e_wait_q[sr].list.prev;
754 	if (ptr == &info->e_wait_q[sr].list)
755 		return NULL;
756 	return list_entry(ptr, struct ext_wait_queue, list);
757 }
758 
759 
set_cookie(struct sk_buff * skb,char code)760 static inline void set_cookie(struct sk_buff *skb, char code)
761 {
762 	((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
763 }
764 
765 /*
766  * The next function is only to split too long sys_mq_timedsend
767  */
__do_notify(struct mqueue_inode_info * info)768 static void __do_notify(struct mqueue_inode_info *info)
769 {
770 	/* notification
771 	 * invoked when there is registered process and there isn't process
772 	 * waiting synchronously for message AND state of queue changed from
773 	 * empty to not empty. Here we are sure that no one is waiting
774 	 * synchronously. */
775 	if (info->notify_owner &&
776 	    info->attr.mq_curmsgs == 1) {
777 		switch (info->notify.sigev_notify) {
778 		case SIGEV_NONE:
779 			break;
780 		case SIGEV_SIGNAL: {
781 			struct kernel_siginfo sig_i;
782 			struct task_struct *task;
783 
784 			/* do_mq_notify() accepts sigev_signo == 0, why?? */
785 			if (!info->notify.sigev_signo)
786 				break;
787 
788 			clear_siginfo(&sig_i);
789 			sig_i.si_signo = info->notify.sigev_signo;
790 			sig_i.si_errno = 0;
791 			sig_i.si_code = SI_MESGQ;
792 			sig_i.si_value = info->notify.sigev_value;
793 			rcu_read_lock();
794 			/* map current pid/uid into info->owner's namespaces */
795 			sig_i.si_pid = task_tgid_nr_ns(current,
796 						ns_of_pid(info->notify_owner));
797 			sig_i.si_uid = from_kuid_munged(info->notify_user_ns,
798 						current_uid());
799 			/*
800 			 * We can't use kill_pid_info(), this signal should
801 			 * bypass check_kill_permission(). It is from kernel
802 			 * but si_fromuser() can't know this.
803 			 * We do check the self_exec_id, to avoid sending
804 			 * signals to programs that don't expect them.
805 			 */
806 			task = pid_task(info->notify_owner, PIDTYPE_TGID);
807 			if (task && task->self_exec_id ==
808 						info->notify_self_exec_id) {
809 				do_send_sig_info(info->notify.sigev_signo,
810 						&sig_i, task, PIDTYPE_TGID);
811 			}
812 			rcu_read_unlock();
813 			break;
814 		}
815 		case SIGEV_THREAD:
816 			set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
817 			netlink_sendskb(info->notify_sock, info->notify_cookie);
818 			break;
819 		}
820 		/* after notification unregisters process */
821 		put_pid(info->notify_owner);
822 		put_user_ns(info->notify_user_ns);
823 		info->notify_owner = NULL;
824 		info->notify_user_ns = NULL;
825 	}
826 	wake_up(&info->wait_q);
827 }
828 
prepare_timeout(const struct __kernel_timespec __user * u_abs_timeout,struct timespec64 * ts)829 static int prepare_timeout(const struct __kernel_timespec __user *u_abs_timeout,
830 			   struct timespec64 *ts)
831 {
832 	if (get_timespec64(ts, u_abs_timeout))
833 		return -EFAULT;
834 	if (!timespec64_valid(ts))
835 		return -EINVAL;
836 	return 0;
837 }
838 
remove_notification(struct mqueue_inode_info * info)839 static void remove_notification(struct mqueue_inode_info *info)
840 {
841 	if (info->notify_owner != NULL &&
842 	    info->notify.sigev_notify == SIGEV_THREAD) {
843 		set_cookie(info->notify_cookie, NOTIFY_REMOVED);
844 		netlink_sendskb(info->notify_sock, info->notify_cookie);
845 	}
846 	put_pid(info->notify_owner);
847 	put_user_ns(info->notify_user_ns);
848 	info->notify_owner = NULL;
849 	info->notify_user_ns = NULL;
850 }
851 
prepare_open(struct dentry * dentry,int oflag,int ro,umode_t mode,struct filename * name,struct mq_attr * attr)852 static int prepare_open(struct dentry *dentry, int oflag, int ro,
853 			umode_t mode, struct filename *name,
854 			struct mq_attr *attr)
855 {
856 	static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
857 						  MAY_READ | MAY_WRITE };
858 	int acc;
859 
860 	if (d_really_is_negative(dentry)) {
861 		if (!(oflag & O_CREAT))
862 			return -ENOENT;
863 		if (ro)
864 			return ro;
865 		audit_inode_parent_hidden(name, dentry->d_parent);
866 		return vfs_mkobj(dentry, mode & ~current_umask(),
867 				  mqueue_create_attr, attr);
868 	}
869 	/* it already existed */
870 	audit_inode(name, dentry, 0);
871 	if ((oflag & (O_CREAT|O_EXCL)) == (O_CREAT|O_EXCL))
872 		return -EEXIST;
873 	if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
874 		return -EINVAL;
875 	acc = oflag2acc[oflag & O_ACCMODE];
876 	return inode_permission(d_inode(dentry), acc);
877 }
878 
do_mq_open(const char __user * u_name,int oflag,umode_t mode,struct mq_attr * attr)879 static int do_mq_open(const char __user *u_name, int oflag, umode_t mode,
880 		      struct mq_attr *attr)
881 {
882 	struct vfsmount *mnt = current->nsproxy->ipc_ns->mq_mnt;
883 	struct dentry *root = mnt->mnt_root;
884 	struct filename *name;
885 	struct path path;
886 	int fd, error;
887 	int ro;
888 
889 	audit_mq_open(oflag, mode, attr);
890 
891 	if (IS_ERR(name = getname(u_name)))
892 		return PTR_ERR(name);
893 
894 	fd = get_unused_fd_flags(O_CLOEXEC);
895 	if (fd < 0)
896 		goto out_putname;
897 
898 	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
899 	inode_lock(d_inode(root));
900 	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
901 	if (IS_ERR(path.dentry)) {
902 		error = PTR_ERR(path.dentry);
903 		goto out_putfd;
904 	}
905 	path.mnt = mntget(mnt);
906 	error = prepare_open(path.dentry, oflag, ro, mode, name, attr);
907 	if (!error) {
908 		struct file *file = dentry_open(&path, oflag, current_cred());
909 		if (!IS_ERR(file))
910 			fd_install(fd, file);
911 		else
912 			error = PTR_ERR(file);
913 	}
914 	path_put(&path);
915 out_putfd:
916 	if (error) {
917 		put_unused_fd(fd);
918 		fd = error;
919 	}
920 	inode_unlock(d_inode(root));
921 	if (!ro)
922 		mnt_drop_write(mnt);
923 out_putname:
924 	putname(name);
925 	return fd;
926 }
927 
SYSCALL_DEFINE4(mq_open,const char __user *,u_name,int,oflag,umode_t,mode,struct mq_attr __user *,u_attr)928 SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
929 		struct mq_attr __user *, u_attr)
930 {
931 	struct mq_attr attr;
932 	if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
933 		return -EFAULT;
934 
935 	return do_mq_open(u_name, oflag, mode, u_attr ? &attr : NULL);
936 }
937 
SYSCALL_DEFINE1(mq_unlink,const char __user *,u_name)938 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
939 {
940 	int err;
941 	struct filename *name;
942 	struct dentry *dentry;
943 	struct inode *inode = NULL;
944 	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
945 	struct vfsmount *mnt = ipc_ns->mq_mnt;
946 
947 	name = getname(u_name);
948 	if (IS_ERR(name))
949 		return PTR_ERR(name);
950 
951 	audit_inode_parent_hidden(name, mnt->mnt_root);
952 	err = mnt_want_write(mnt);
953 	if (err)
954 		goto out_name;
955 	inode_lock_nested(d_inode(mnt->mnt_root), I_MUTEX_PARENT);
956 	dentry = lookup_one_len(name->name, mnt->mnt_root,
957 				strlen(name->name));
958 	if (IS_ERR(dentry)) {
959 		err = PTR_ERR(dentry);
960 		goto out_unlock;
961 	}
962 
963 	inode = d_inode(dentry);
964 	if (!inode) {
965 		err = -ENOENT;
966 	} else {
967 		ihold(inode);
968 		err = vfs_unlink(d_inode(dentry->d_parent), dentry, NULL);
969 	}
970 	dput(dentry);
971 
972 out_unlock:
973 	inode_unlock(d_inode(mnt->mnt_root));
974 	if (inode)
975 		iput(inode);
976 	mnt_drop_write(mnt);
977 out_name:
978 	putname(name);
979 
980 	return err;
981 }
982 
983 /* Pipelined send and receive functions.
984  *
985  * If a receiver finds no waiting message, then it registers itself in the
986  * list of waiting receivers. A sender checks that list before adding the new
987  * message into the message array. If there is a waiting receiver, then it
988  * bypasses the message array and directly hands the message over to the
989  * receiver. The receiver accepts the message and returns without grabbing the
990  * queue spinlock:
991  *
992  * - Set pointer to message.
993  * - Queue the receiver task for later wakeup (without the info->lock).
994  * - Update its state to STATE_READY. Now the receiver can continue.
995  * - Wake up the process after the lock is dropped. Should the process wake up
996  *   before this wakeup (due to a timeout or a signal) it will either see
997  *   STATE_READY and continue or acquire the lock to check the state again.
998  *
999  * The same algorithm is used for senders.
1000  */
1001 
__pipelined_op(struct wake_q_head * wake_q,struct mqueue_inode_info * info,struct ext_wait_queue * this)1002 static inline void __pipelined_op(struct wake_q_head *wake_q,
1003 				  struct mqueue_inode_info *info,
1004 				  struct ext_wait_queue *this)
1005 {
1006 	list_del(&this->list);
1007 	get_task_struct(this->task);
1008 
1009 	/* see MQ_BARRIER for purpose/pairing */
1010 	smp_store_release(&this->state, STATE_READY);
1011 	wake_q_add_safe(wake_q, this->task);
1012 }
1013 
1014 /* pipelined_send() - send a message directly to the task waiting in
1015  * sys_mq_timedreceive() (without inserting message into a queue).
1016  */
pipelined_send(struct wake_q_head * wake_q,struct mqueue_inode_info * info,struct msg_msg * message,struct ext_wait_queue * receiver)1017 static inline void pipelined_send(struct wake_q_head *wake_q,
1018 				  struct mqueue_inode_info *info,
1019 				  struct msg_msg *message,
1020 				  struct ext_wait_queue *receiver)
1021 {
1022 	receiver->msg = message;
1023 	__pipelined_op(wake_q, info, receiver);
1024 }
1025 
1026 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
1027  * gets its message and put to the queue (we have one free place for sure). */
pipelined_receive(struct wake_q_head * wake_q,struct mqueue_inode_info * info)1028 static inline void pipelined_receive(struct wake_q_head *wake_q,
1029 				     struct mqueue_inode_info *info)
1030 {
1031 	struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
1032 
1033 	if (!sender) {
1034 		/* for poll */
1035 		wake_up_interruptible(&info->wait_q);
1036 		return;
1037 	}
1038 	if (msg_insert(sender->msg, info))
1039 		return;
1040 
1041 	__pipelined_op(wake_q, info, sender);
1042 }
1043 
do_mq_timedsend(mqd_t mqdes,const char __user * u_msg_ptr,size_t msg_len,unsigned int msg_prio,struct timespec64 * ts)1044 static int do_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
1045 		size_t msg_len, unsigned int msg_prio,
1046 		struct timespec64 *ts)
1047 {
1048 	struct fd f;
1049 	struct inode *inode;
1050 	struct ext_wait_queue wait;
1051 	struct ext_wait_queue *receiver;
1052 	struct msg_msg *msg_ptr;
1053 	struct mqueue_inode_info *info;
1054 	ktime_t expires, *timeout = NULL;
1055 	struct posix_msg_tree_node *new_leaf = NULL;
1056 	int ret = 0;
1057 	DEFINE_WAKE_Q(wake_q);
1058 
1059 	if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
1060 		return -EINVAL;
1061 
1062 	if (ts) {
1063 		expires = timespec64_to_ktime(*ts);
1064 		timeout = &expires;
1065 	}
1066 
1067 	audit_mq_sendrecv(mqdes, msg_len, msg_prio, ts);
1068 
1069 	f = fdget(mqdes);
1070 	if (unlikely(!f.file)) {
1071 		ret = -EBADF;
1072 		goto out;
1073 	}
1074 
1075 	inode = file_inode(f.file);
1076 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1077 		ret = -EBADF;
1078 		goto out_fput;
1079 	}
1080 	info = MQUEUE_I(inode);
1081 	audit_file(f.file);
1082 
1083 	if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
1084 		ret = -EBADF;
1085 		goto out_fput;
1086 	}
1087 
1088 	if (unlikely(msg_len > info->attr.mq_msgsize)) {
1089 		ret = -EMSGSIZE;
1090 		goto out_fput;
1091 	}
1092 
1093 	/* First try to allocate memory, before doing anything with
1094 	 * existing queues. */
1095 	msg_ptr = load_msg(u_msg_ptr, msg_len);
1096 	if (IS_ERR(msg_ptr)) {
1097 		ret = PTR_ERR(msg_ptr);
1098 		goto out_fput;
1099 	}
1100 	msg_ptr->m_ts = msg_len;
1101 	msg_ptr->m_type = msg_prio;
1102 
1103 	/*
1104 	 * msg_insert really wants us to have a valid, spare node struct so
1105 	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1106 	 * fall back to that if necessary.
1107 	 */
1108 	if (!info->node_cache)
1109 		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1110 
1111 	spin_lock(&info->lock);
1112 
1113 	if (!info->node_cache && new_leaf) {
1114 		/* Save our speculative allocation into the cache */
1115 		INIT_LIST_HEAD(&new_leaf->msg_list);
1116 		info->node_cache = new_leaf;
1117 		new_leaf = NULL;
1118 	} else {
1119 		kfree(new_leaf);
1120 	}
1121 
1122 	if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1123 		if (f.file->f_flags & O_NONBLOCK) {
1124 			ret = -EAGAIN;
1125 		} else {
1126 			wait.task = current;
1127 			wait.msg = (void *) msg_ptr;
1128 
1129 			/* memory barrier not required, we hold info->lock */
1130 			WRITE_ONCE(wait.state, STATE_NONE);
1131 			ret = wq_sleep(info, SEND, timeout, &wait);
1132 			/*
1133 			 * wq_sleep must be called with info->lock held, and
1134 			 * returns with the lock released
1135 			 */
1136 			goto out_free;
1137 		}
1138 	} else {
1139 		receiver = wq_get_first_waiter(info, RECV);
1140 		if (receiver) {
1141 			pipelined_send(&wake_q, info, msg_ptr, receiver);
1142 		} else {
1143 			/* adds message to the queue */
1144 			ret = msg_insert(msg_ptr, info);
1145 			if (ret)
1146 				goto out_unlock;
1147 			__do_notify(info);
1148 		}
1149 		inode->i_atime = inode->i_mtime = inode->i_ctime =
1150 				current_time(inode);
1151 	}
1152 out_unlock:
1153 	spin_unlock(&info->lock);
1154 	wake_up_q(&wake_q);
1155 out_free:
1156 	if (ret)
1157 		free_msg(msg_ptr);
1158 out_fput:
1159 	fdput(f);
1160 out:
1161 	return ret;
1162 }
1163 
do_mq_timedreceive(mqd_t mqdes,char __user * u_msg_ptr,size_t msg_len,unsigned int __user * u_msg_prio,struct timespec64 * ts)1164 static int do_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
1165 		size_t msg_len, unsigned int __user *u_msg_prio,
1166 		struct timespec64 *ts)
1167 {
1168 	ssize_t ret;
1169 	struct msg_msg *msg_ptr;
1170 	struct fd f;
1171 	struct inode *inode;
1172 	struct mqueue_inode_info *info;
1173 	struct ext_wait_queue wait;
1174 	ktime_t expires, *timeout = NULL;
1175 	struct posix_msg_tree_node *new_leaf = NULL;
1176 
1177 	if (ts) {
1178 		expires = timespec64_to_ktime(*ts);
1179 		timeout = &expires;
1180 	}
1181 
1182 	audit_mq_sendrecv(mqdes, msg_len, 0, ts);
1183 
1184 	f = fdget(mqdes);
1185 	if (unlikely(!f.file)) {
1186 		ret = -EBADF;
1187 		goto out;
1188 	}
1189 
1190 	inode = file_inode(f.file);
1191 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1192 		ret = -EBADF;
1193 		goto out_fput;
1194 	}
1195 	info = MQUEUE_I(inode);
1196 	audit_file(f.file);
1197 
1198 	if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1199 		ret = -EBADF;
1200 		goto out_fput;
1201 	}
1202 
1203 	/* checks if buffer is big enough */
1204 	if (unlikely(msg_len < info->attr.mq_msgsize)) {
1205 		ret = -EMSGSIZE;
1206 		goto out_fput;
1207 	}
1208 
1209 	/*
1210 	 * msg_insert really wants us to have a valid, spare node struct so
1211 	 * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1212 	 * fall back to that if necessary.
1213 	 */
1214 	if (!info->node_cache)
1215 		new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1216 
1217 	spin_lock(&info->lock);
1218 
1219 	if (!info->node_cache && new_leaf) {
1220 		/* Save our speculative allocation into the cache */
1221 		INIT_LIST_HEAD(&new_leaf->msg_list);
1222 		info->node_cache = new_leaf;
1223 	} else {
1224 		kfree(new_leaf);
1225 	}
1226 
1227 	if (info->attr.mq_curmsgs == 0) {
1228 		if (f.file->f_flags & O_NONBLOCK) {
1229 			spin_unlock(&info->lock);
1230 			ret = -EAGAIN;
1231 		} else {
1232 			wait.task = current;
1233 
1234 			/* memory barrier not required, we hold info->lock */
1235 			WRITE_ONCE(wait.state, STATE_NONE);
1236 			ret = wq_sleep(info, RECV, timeout, &wait);
1237 			msg_ptr = wait.msg;
1238 		}
1239 	} else {
1240 		DEFINE_WAKE_Q(wake_q);
1241 
1242 		msg_ptr = msg_get(info);
1243 
1244 		inode->i_atime = inode->i_mtime = inode->i_ctime =
1245 				current_time(inode);
1246 
1247 		/* There is now free space in queue. */
1248 		pipelined_receive(&wake_q, info);
1249 		spin_unlock(&info->lock);
1250 		wake_up_q(&wake_q);
1251 		ret = 0;
1252 	}
1253 	if (ret == 0) {
1254 		ret = msg_ptr->m_ts;
1255 
1256 		if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1257 			store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1258 			ret = -EFAULT;
1259 		}
1260 		free_msg(msg_ptr);
1261 	}
1262 out_fput:
1263 	fdput(f);
1264 out:
1265 	return ret;
1266 }
1267 
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)1268 SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
1269 		size_t, msg_len, unsigned int, msg_prio,
1270 		const struct __kernel_timespec __user *, u_abs_timeout)
1271 {
1272 	struct timespec64 ts, *p = NULL;
1273 	if (u_abs_timeout) {
1274 		int res = prepare_timeout(u_abs_timeout, &ts);
1275 		if (res)
1276 			return res;
1277 		p = &ts;
1278 	}
1279 	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1280 }
1281 
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)1282 SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1283 		size_t, msg_len, unsigned int __user *, u_msg_prio,
1284 		const struct __kernel_timespec __user *, u_abs_timeout)
1285 {
1286 	struct timespec64 ts, *p = NULL;
1287 	if (u_abs_timeout) {
1288 		int res = prepare_timeout(u_abs_timeout, &ts);
1289 		if (res)
1290 			return res;
1291 		p = &ts;
1292 	}
1293 	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1294 }
1295 
1296 /*
1297  * Notes: the case when user wants us to deregister (with NULL as pointer)
1298  * and he isn't currently owner of notification, will be silently discarded.
1299  * It isn't explicitly defined in the POSIX.
1300  */
do_mq_notify(mqd_t mqdes,const struct sigevent * notification)1301 static int do_mq_notify(mqd_t mqdes, const struct sigevent *notification)
1302 {
1303 	int ret;
1304 	struct fd f;
1305 	struct sock *sock;
1306 	struct inode *inode;
1307 	struct mqueue_inode_info *info;
1308 	struct sk_buff *nc;
1309 
1310 	audit_mq_notify(mqdes, notification);
1311 
1312 	nc = NULL;
1313 	sock = NULL;
1314 	if (notification != NULL) {
1315 		if (unlikely(notification->sigev_notify != SIGEV_NONE &&
1316 			     notification->sigev_notify != SIGEV_SIGNAL &&
1317 			     notification->sigev_notify != SIGEV_THREAD))
1318 			return -EINVAL;
1319 		if (notification->sigev_notify == SIGEV_SIGNAL &&
1320 			!valid_signal(notification->sigev_signo)) {
1321 			return -EINVAL;
1322 		}
1323 		if (notification->sigev_notify == SIGEV_THREAD) {
1324 			long timeo;
1325 
1326 			/* create the notify skb */
1327 			nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1328 			if (!nc)
1329 				return -ENOMEM;
1330 
1331 			if (copy_from_user(nc->data,
1332 					notification->sigev_value.sival_ptr,
1333 					NOTIFY_COOKIE_LEN)) {
1334 				ret = -EFAULT;
1335 				goto free_skb;
1336 			}
1337 
1338 			/* TODO: add a header? */
1339 			skb_put(nc, NOTIFY_COOKIE_LEN);
1340 			/* and attach it to the socket */
1341 retry:
1342 			f = fdget(notification->sigev_signo);
1343 			if (!f.file) {
1344 				ret = -EBADF;
1345 				goto out;
1346 			}
1347 			sock = netlink_getsockbyfilp(f.file);
1348 			fdput(f);
1349 			if (IS_ERR(sock)) {
1350 				ret = PTR_ERR(sock);
1351 				goto free_skb;
1352 			}
1353 
1354 			timeo = MAX_SCHEDULE_TIMEOUT;
1355 			ret = netlink_attachskb(sock, nc, &timeo, NULL);
1356 			if (ret == 1) {
1357 				sock = NULL;
1358 				goto retry;
1359 			}
1360 			if (ret)
1361 				return ret;
1362 		}
1363 	}
1364 
1365 	f = fdget(mqdes);
1366 	if (!f.file) {
1367 		ret = -EBADF;
1368 		goto out;
1369 	}
1370 
1371 	inode = file_inode(f.file);
1372 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1373 		ret = -EBADF;
1374 		goto out_fput;
1375 	}
1376 	info = MQUEUE_I(inode);
1377 
1378 	ret = 0;
1379 	spin_lock(&info->lock);
1380 	if (notification == NULL) {
1381 		if (info->notify_owner == task_tgid(current)) {
1382 			remove_notification(info);
1383 			inode->i_atime = inode->i_ctime = current_time(inode);
1384 		}
1385 	} else if (info->notify_owner != NULL) {
1386 		ret = -EBUSY;
1387 	} else {
1388 		switch (notification->sigev_notify) {
1389 		case SIGEV_NONE:
1390 			info->notify.sigev_notify = SIGEV_NONE;
1391 			break;
1392 		case SIGEV_THREAD:
1393 			info->notify_sock = sock;
1394 			info->notify_cookie = nc;
1395 			sock = NULL;
1396 			nc = NULL;
1397 			info->notify.sigev_notify = SIGEV_THREAD;
1398 			break;
1399 		case SIGEV_SIGNAL:
1400 			info->notify.sigev_signo = notification->sigev_signo;
1401 			info->notify.sigev_value = notification->sigev_value;
1402 			info->notify.sigev_notify = SIGEV_SIGNAL;
1403 			info->notify_self_exec_id = current->self_exec_id;
1404 			break;
1405 		}
1406 
1407 		info->notify_owner = get_pid(task_tgid(current));
1408 		info->notify_user_ns = get_user_ns(current_user_ns());
1409 		inode->i_atime = inode->i_ctime = current_time(inode);
1410 	}
1411 	spin_unlock(&info->lock);
1412 out_fput:
1413 	fdput(f);
1414 out:
1415 	if (sock)
1416 		netlink_detachskb(sock, nc);
1417 	else
1418 free_skb:
1419 		dev_kfree_skb(nc);
1420 
1421 	return ret;
1422 }
1423 
SYSCALL_DEFINE2(mq_notify,mqd_t,mqdes,const struct sigevent __user *,u_notification)1424 SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1425 		const struct sigevent __user *, u_notification)
1426 {
1427 	struct sigevent n, *p = NULL;
1428 	if (u_notification) {
1429 		if (copy_from_user(&n, u_notification, sizeof(struct sigevent)))
1430 			return -EFAULT;
1431 		p = &n;
1432 	}
1433 	return do_mq_notify(mqdes, p);
1434 }
1435 
do_mq_getsetattr(int mqdes,struct mq_attr * new,struct mq_attr * old)1436 static int do_mq_getsetattr(int mqdes, struct mq_attr *new, struct mq_attr *old)
1437 {
1438 	struct fd f;
1439 	struct inode *inode;
1440 	struct mqueue_inode_info *info;
1441 
1442 	if (new && (new->mq_flags & (~O_NONBLOCK)))
1443 		return -EINVAL;
1444 
1445 	f = fdget(mqdes);
1446 	if (!f.file)
1447 		return -EBADF;
1448 
1449 	if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1450 		fdput(f);
1451 		return -EBADF;
1452 	}
1453 
1454 	inode = file_inode(f.file);
1455 	info = MQUEUE_I(inode);
1456 
1457 	spin_lock(&info->lock);
1458 
1459 	if (old) {
1460 		*old = info->attr;
1461 		old->mq_flags = f.file->f_flags & O_NONBLOCK;
1462 	}
1463 	if (new) {
1464 		audit_mq_getsetattr(mqdes, new);
1465 		spin_lock(&f.file->f_lock);
1466 		if (new->mq_flags & O_NONBLOCK)
1467 			f.file->f_flags |= O_NONBLOCK;
1468 		else
1469 			f.file->f_flags &= ~O_NONBLOCK;
1470 		spin_unlock(&f.file->f_lock);
1471 
1472 		inode->i_atime = inode->i_ctime = current_time(inode);
1473 	}
1474 
1475 	spin_unlock(&info->lock);
1476 	fdput(f);
1477 	return 0;
1478 }
1479 
SYSCALL_DEFINE3(mq_getsetattr,mqd_t,mqdes,const struct mq_attr __user *,u_mqstat,struct mq_attr __user *,u_omqstat)1480 SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1481 		const struct mq_attr __user *, u_mqstat,
1482 		struct mq_attr __user *, u_omqstat)
1483 {
1484 	int ret;
1485 	struct mq_attr mqstat, omqstat;
1486 	struct mq_attr *new = NULL, *old = NULL;
1487 
1488 	if (u_mqstat) {
1489 		new = &mqstat;
1490 		if (copy_from_user(new, u_mqstat, sizeof(struct mq_attr)))
1491 			return -EFAULT;
1492 	}
1493 	if (u_omqstat)
1494 		old = &omqstat;
1495 
1496 	ret = do_mq_getsetattr(mqdes, new, old);
1497 	if (ret || !old)
1498 		return ret;
1499 
1500 	if (copy_to_user(u_omqstat, old, sizeof(struct mq_attr)))
1501 		return -EFAULT;
1502 	return 0;
1503 }
1504 
1505 #ifdef CONFIG_COMPAT
1506 
1507 struct compat_mq_attr {
1508 	compat_long_t mq_flags;      /* message queue flags		     */
1509 	compat_long_t mq_maxmsg;     /* maximum number of messages	     */
1510 	compat_long_t mq_msgsize;    /* maximum message size		     */
1511 	compat_long_t mq_curmsgs;    /* number of messages currently queued  */
1512 	compat_long_t __reserved[4]; /* ignored for input, zeroed for output */
1513 };
1514 
get_compat_mq_attr(struct mq_attr * attr,const struct compat_mq_attr __user * uattr)1515 static inline int get_compat_mq_attr(struct mq_attr *attr,
1516 			const struct compat_mq_attr __user *uattr)
1517 {
1518 	struct compat_mq_attr v;
1519 
1520 	if (copy_from_user(&v, uattr, sizeof(*uattr)))
1521 		return -EFAULT;
1522 
1523 	memset(attr, 0, sizeof(*attr));
1524 	attr->mq_flags = v.mq_flags;
1525 	attr->mq_maxmsg = v.mq_maxmsg;
1526 	attr->mq_msgsize = v.mq_msgsize;
1527 	attr->mq_curmsgs = v.mq_curmsgs;
1528 	return 0;
1529 }
1530 
put_compat_mq_attr(const struct mq_attr * attr,struct compat_mq_attr __user * uattr)1531 static inline int put_compat_mq_attr(const struct mq_attr *attr,
1532 			struct compat_mq_attr __user *uattr)
1533 {
1534 	struct compat_mq_attr v;
1535 
1536 	memset(&v, 0, sizeof(v));
1537 	v.mq_flags = attr->mq_flags;
1538 	v.mq_maxmsg = attr->mq_maxmsg;
1539 	v.mq_msgsize = attr->mq_msgsize;
1540 	v.mq_curmsgs = attr->mq_curmsgs;
1541 	if (copy_to_user(uattr, &v, sizeof(*uattr)))
1542 		return -EFAULT;
1543 	return 0;
1544 }
1545 
COMPAT_SYSCALL_DEFINE4(mq_open,const char __user *,u_name,int,oflag,compat_mode_t,mode,struct compat_mq_attr __user *,u_attr)1546 COMPAT_SYSCALL_DEFINE4(mq_open, const char __user *, u_name,
1547 		       int, oflag, compat_mode_t, mode,
1548 		       struct compat_mq_attr __user *, u_attr)
1549 {
1550 	struct mq_attr attr, *p = NULL;
1551 	if (u_attr && oflag & O_CREAT) {
1552 		p = &attr;
1553 		if (get_compat_mq_attr(&attr, u_attr))
1554 			return -EFAULT;
1555 	}
1556 	return do_mq_open(u_name, oflag, mode, p);
1557 }
1558 
COMPAT_SYSCALL_DEFINE2(mq_notify,mqd_t,mqdes,const struct compat_sigevent __user *,u_notification)1559 COMPAT_SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1560 		       const struct compat_sigevent __user *, u_notification)
1561 {
1562 	struct sigevent n, *p = NULL;
1563 	if (u_notification) {
1564 		if (get_compat_sigevent(&n, u_notification))
1565 			return -EFAULT;
1566 		if (n.sigev_notify == SIGEV_THREAD)
1567 			n.sigev_value.sival_ptr = compat_ptr(n.sigev_value.sival_int);
1568 		p = &n;
1569 	}
1570 	return do_mq_notify(mqdes, p);
1571 }
1572 
COMPAT_SYSCALL_DEFINE3(mq_getsetattr,mqd_t,mqdes,const struct compat_mq_attr __user *,u_mqstat,struct compat_mq_attr __user *,u_omqstat)1573 COMPAT_SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1574 		       const struct compat_mq_attr __user *, u_mqstat,
1575 		       struct compat_mq_attr __user *, u_omqstat)
1576 {
1577 	int ret;
1578 	struct mq_attr mqstat, omqstat;
1579 	struct mq_attr *new = NULL, *old = NULL;
1580 
1581 	if (u_mqstat) {
1582 		new = &mqstat;
1583 		if (get_compat_mq_attr(new, u_mqstat))
1584 			return -EFAULT;
1585 	}
1586 	if (u_omqstat)
1587 		old = &omqstat;
1588 
1589 	ret = do_mq_getsetattr(mqdes, new, old);
1590 	if (ret || !old)
1591 		return ret;
1592 
1593 	if (put_compat_mq_attr(old, u_omqstat))
1594 		return -EFAULT;
1595 	return 0;
1596 }
1597 #endif
1598 
1599 #ifdef CONFIG_COMPAT_32BIT_TIME
compat_prepare_timeout(const struct old_timespec32 __user * p,struct timespec64 * ts)1600 static int compat_prepare_timeout(const struct old_timespec32 __user *p,
1601 				   struct timespec64 *ts)
1602 {
1603 	if (get_old_timespec32(ts, p))
1604 		return -EFAULT;
1605 	if (!timespec64_valid(ts))
1606 		return -EINVAL;
1607 	return 0;
1608 }
1609 
SYSCALL_DEFINE5(mq_timedsend_time32,mqd_t,mqdes,const char __user *,u_msg_ptr,unsigned int,msg_len,unsigned int,msg_prio,const struct old_timespec32 __user *,u_abs_timeout)1610 SYSCALL_DEFINE5(mq_timedsend_time32, mqd_t, mqdes,
1611 		const char __user *, u_msg_ptr,
1612 		unsigned int, msg_len, unsigned int, msg_prio,
1613 		const struct old_timespec32 __user *, u_abs_timeout)
1614 {
1615 	struct timespec64 ts, *p = NULL;
1616 	if (u_abs_timeout) {
1617 		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1618 		if (res)
1619 			return res;
1620 		p = &ts;
1621 	}
1622 	return do_mq_timedsend(mqdes, u_msg_ptr, msg_len, msg_prio, p);
1623 }
1624 
SYSCALL_DEFINE5(mq_timedreceive_time32,mqd_t,mqdes,char __user *,u_msg_ptr,unsigned int,msg_len,unsigned int __user *,u_msg_prio,const struct old_timespec32 __user *,u_abs_timeout)1625 SYSCALL_DEFINE5(mq_timedreceive_time32, mqd_t, mqdes,
1626 		char __user *, u_msg_ptr,
1627 		unsigned int, msg_len, unsigned int __user *, u_msg_prio,
1628 		const struct old_timespec32 __user *, u_abs_timeout)
1629 {
1630 	struct timespec64 ts, *p = NULL;
1631 	if (u_abs_timeout) {
1632 		int res = compat_prepare_timeout(u_abs_timeout, &ts);
1633 		if (res)
1634 			return res;
1635 		p = &ts;
1636 	}
1637 	return do_mq_timedreceive(mqdes, u_msg_ptr, msg_len, u_msg_prio, p);
1638 }
1639 #endif
1640 
1641 static const struct inode_operations mqueue_dir_inode_operations = {
1642 	.lookup = simple_lookup,
1643 	.create = mqueue_create,
1644 	.unlink = mqueue_unlink,
1645 };
1646 
1647 static const struct file_operations mqueue_file_operations = {
1648 	.flush = mqueue_flush_file,
1649 	.poll = mqueue_poll_file,
1650 	.read = mqueue_read_file,
1651 	.llseek = default_llseek,
1652 };
1653 
1654 static const struct super_operations mqueue_super_ops = {
1655 	.alloc_inode = mqueue_alloc_inode,
1656 	.free_inode = mqueue_free_inode,
1657 	.evict_inode = mqueue_evict_inode,
1658 	.statfs = simple_statfs,
1659 };
1660 
1661 static const struct fs_context_operations mqueue_fs_context_ops = {
1662 	.free		= mqueue_fs_context_free,
1663 	.get_tree	= mqueue_get_tree,
1664 };
1665 
1666 static struct file_system_type mqueue_fs_type = {
1667 	.name			= "mqueue",
1668 	.init_fs_context	= mqueue_init_fs_context,
1669 	.kill_sb		= kill_litter_super,
1670 	.fs_flags		= FS_USERNS_MOUNT,
1671 };
1672 
mq_init_ns(struct ipc_namespace * ns)1673 int mq_init_ns(struct ipc_namespace *ns)
1674 {
1675 	struct vfsmount *m;
1676 
1677 	ns->mq_queues_count  = 0;
1678 	ns->mq_queues_max    = DFLT_QUEUESMAX;
1679 	ns->mq_msg_max       = DFLT_MSGMAX;
1680 	ns->mq_msgsize_max   = DFLT_MSGSIZEMAX;
1681 	ns->mq_msg_default   = DFLT_MSG;
1682 	ns->mq_msgsize_default  = DFLT_MSGSIZE;
1683 
1684 	m = mq_create_mount(ns);
1685 	if (IS_ERR(m))
1686 		return PTR_ERR(m);
1687 	ns->mq_mnt = m;
1688 	return 0;
1689 }
1690 
mq_clear_sbinfo(struct ipc_namespace * ns)1691 void mq_clear_sbinfo(struct ipc_namespace *ns)
1692 {
1693 	ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1694 }
1695 
mq_put_mnt(struct ipc_namespace * ns)1696 void mq_put_mnt(struct ipc_namespace *ns)
1697 {
1698 	kern_unmount(ns->mq_mnt);
1699 }
1700 
init_mqueue_fs(void)1701 static int __init init_mqueue_fs(void)
1702 {
1703 	int error;
1704 
1705 	mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1706 				sizeof(struct mqueue_inode_info), 0,
1707 				SLAB_HWCACHE_ALIGN|SLAB_ACCOUNT, init_once);
1708 	if (mqueue_inode_cachep == NULL)
1709 		return -ENOMEM;
1710 
1711 	/* ignore failures - they are not fatal */
1712 	mq_sysctl_table = mq_register_sysctl_table();
1713 
1714 	error = register_filesystem(&mqueue_fs_type);
1715 	if (error)
1716 		goto out_sysctl;
1717 
1718 	spin_lock_init(&mq_lock);
1719 
1720 	error = mq_init_ns(&init_ipc_ns);
1721 	if (error)
1722 		goto out_filesystem;
1723 
1724 	return 0;
1725 
1726 out_filesystem:
1727 	unregister_filesystem(&mqueue_fs_type);
1728 out_sysctl:
1729 	if (mq_sysctl_table)
1730 		unregister_sysctl_table(mq_sysctl_table);
1731 	kmem_cache_destroy(mqueue_inode_cachep);
1732 	return error;
1733 }
1734 
1735 device_initcall(init_mqueue_fs);
1736