1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/msg.c
4 * Copyright (C) 1992 Krishna Balasubramanian
5 *
6 * Removed all the remaining kerneld mess
7 * Catch the -EFAULT stuff properly
8 * Use GFP_KERNEL for messages as in 1.2
9 * Fixed up the unchecked user space derefs
10 * Copyright (C) 1998 Alan Cox & Andi Kleen
11 *
12 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
13 *
14 * mostly rewritten, threaded and wake-one semantics added
15 * MSGMAX limit removed, sysctl's added
16 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
17 *
18 * support for audit of ipc object properties and permission changes
19 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
20 *
21 * namespaces support
22 * OpenVZ, SWsoft Inc.
23 * Pavel Emelianov <xemul@openvz.org>
24 */
25
26#include <linux/capability.h>
27#include <linux/msg.h>
28#include <linux/spinlock.h>
29#include <linux/init.h>
30#include <linux/mm.h>
31#include <linux/proc_fs.h>
32#include <linux/list.h>
33#include <linux/security.h>
34#include <linux/sched/wake_q.h>
35#include <linux/syscalls.h>
36#include <linux/audit.h>
37#include <linux/seq_file.h>
38#include <linux/rwsem.h>
39#include <linux/nsproxy.h>
40#include <linux/ipc_namespace.h>
41#include <linux/rhashtable.h>
42
43#include <asm/current.h>
44#include <linux/uaccess.h>
45#include "util.h"
46
47/* one msq_queue structure for each present queue on the system */
48struct msg_queue {
49	struct kern_ipc_perm q_perm;
50	time64_t q_stime;		/* last msgsnd time */
51	time64_t q_rtime;		/* last msgrcv time */
52	time64_t q_ctime;		/* last change time */
53	unsigned long q_cbytes;		/* current number of bytes on queue */
54	unsigned long q_qnum;		/* number of messages in queue */
55	unsigned long q_qbytes;		/* max number of bytes on queue */
56	struct pid *q_lspid;		/* pid of last msgsnd */
57	struct pid *q_lrpid;		/* last receive pid */
58
59	struct list_head q_messages;
60	struct list_head q_receivers;
61	struct list_head q_senders;
62} __randomize_layout;
63
64/*
65 * MSG_BARRIER Locking:
66 *
67 * Similar to the optimization used in ipc/mqueue.c, one syscall return path
68 * does not acquire any locks when it sees that a message exists in
69 * msg_receiver.r_msg. Therefore r_msg is set using smp_store_release()
70 * and accessed using READ_ONCE()+smp_acquire__after_ctrl_dep(). In addition,
71 * wake_q_add_safe() is used. See ipc/mqueue.c for more details
72 */
73
74/* one msg_receiver structure for each sleeping receiver */
75struct msg_receiver {
76	struct list_head	r_list;
77	struct task_struct	*r_tsk;
78
79	int			r_mode;
80	long			r_msgtype;
81	long			r_maxsize;
82
83	struct msg_msg		*r_msg;
84};
85
86/* one msg_sender for each sleeping sender */
87struct msg_sender {
88	struct list_head	list;
89	struct task_struct	*tsk;
90	size_t                  msgsz;
91};
92
93#define SEARCH_ANY		1
94#define SEARCH_EQUAL		2
95#define SEARCH_NOTEQUAL		3
96#define SEARCH_LESSEQUAL	4
97#define SEARCH_NUMBER		5
98
99#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
100
101static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
102{
103	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
104
105	if (IS_ERR(ipcp))
106		return ERR_CAST(ipcp);
107
108	return container_of(ipcp, struct msg_queue, q_perm);
109}
110
111static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
112							int id)
113{
114	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
115
116	if (IS_ERR(ipcp))
117		return ERR_CAST(ipcp);
118
119	return container_of(ipcp, struct msg_queue, q_perm);
120}
121
122static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
123{
124	ipc_rmid(&msg_ids(ns), &s->q_perm);
125}
126
127static void msg_rcu_free(struct rcu_head *head)
128{
129	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
130	struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
131
132	security_msg_queue_free(&msq->q_perm);
133	kfree(msq);
134}
135
136/**
137 * newque - Create a new msg queue
138 * @ns: namespace
139 * @params: ptr to the structure that contains the key and msgflg
140 *
141 * Called with msg_ids.rwsem held (writer)
142 */
143static int newque(struct ipc_namespace *ns, struct ipc_params *params)
144{
145	struct msg_queue *msq;
146	int retval;
147	key_t key = params->key;
148	int msgflg = params->flg;
149
150	msq = kmalloc(sizeof(*msq), GFP_KERNEL_ACCOUNT);
151	if (unlikely(!msq))
152		return -ENOMEM;
153
154	msq->q_perm.mode = msgflg & S_IRWXUGO;
155	msq->q_perm.key = key;
156
157	msq->q_perm.security = NULL;
158	retval = security_msg_queue_alloc(&msq->q_perm);
159	if (retval) {
160		kfree(msq);
161		return retval;
162	}
163
164	msq->q_stime = msq->q_rtime = 0;
165	msq->q_ctime = ktime_get_real_seconds();
166	msq->q_cbytes = msq->q_qnum = 0;
167	msq->q_qbytes = ns->msg_ctlmnb;
168	msq->q_lspid = msq->q_lrpid = NULL;
169	INIT_LIST_HEAD(&msq->q_messages);
170	INIT_LIST_HEAD(&msq->q_receivers);
171	INIT_LIST_HEAD(&msq->q_senders);
172
173	/* ipc_addid() locks msq upon success. */
174	retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
175	if (retval < 0) {
176		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
177		return retval;
178	}
179
180	ipc_unlock_object(&msq->q_perm);
181	rcu_read_unlock();
182
183	return msq->q_perm.id;
184}
185
186static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
187{
188	return msgsz + msq->q_cbytes <= msq->q_qbytes &&
189		1 + msq->q_qnum <= msq->q_qbytes;
190}
191
192static inline void ss_add(struct msg_queue *msq,
193			  struct msg_sender *mss, size_t msgsz)
194{
195	mss->tsk = current;
196	mss->msgsz = msgsz;
197	/*
198	 * No memory barrier required: we did ipc_lock_object(),
199	 * and the waker obtains that lock before calling wake_q_add().
200	 */
201	__set_current_state(TASK_INTERRUPTIBLE);
202	list_add_tail(&mss->list, &msq->q_senders);
203}
204
205static inline void ss_del(struct msg_sender *mss)
206{
207	if (mss->list.next)
208		list_del(&mss->list);
209}
210
211static void ss_wakeup(struct msg_queue *msq,
212		      struct wake_q_head *wake_q, bool kill)
213{
214	struct msg_sender *mss, *t;
215	struct task_struct *stop_tsk = NULL;
216	struct list_head *h = &msq->q_senders;
217
218	list_for_each_entry_safe(mss, t, h, list) {
219		if (kill)
220			mss->list.next = NULL;
221
222		/*
223		 * Stop at the first task we don't wakeup,
224		 * we've already iterated the original
225		 * sender queue.
226		 */
227		else if (stop_tsk == mss->tsk)
228			break;
229		/*
230		 * We are not in an EIDRM scenario here, therefore
231		 * verify that we really need to wakeup the task.
232		 * To maintain current semantics and wakeup order,
233		 * move the sender to the tail on behalf of the
234		 * blocked task.
235		 */
236		else if (!msg_fits_inqueue(msq, mss->msgsz)) {
237			if (!stop_tsk)
238				stop_tsk = mss->tsk;
239
240			list_move_tail(&mss->list, &msq->q_senders);
241			continue;
242		}
243
244		wake_q_add(wake_q, mss->tsk);
245	}
246}
247
248static void expunge_all(struct msg_queue *msq, int res,
249			struct wake_q_head *wake_q)
250{
251	struct msg_receiver *msr, *t;
252
253	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
254		struct task_struct *r_tsk;
255
256		r_tsk = get_task_struct(msr->r_tsk);
257
258		/* see MSG_BARRIER for purpose/pairing */
259		smp_store_release(&msr->r_msg, ERR_PTR(res));
260		wake_q_add_safe(wake_q, r_tsk);
261	}
262}
263
264/*
265 * freeque() wakes up waiters on the sender and receiver waiting queue,
266 * removes the message queue from message queue ID IDR, and cleans up all the
267 * messages associated with this queue.
268 *
269 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
270 * before freeque() is called. msg_ids.rwsem remains locked on exit.
271 */
272static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
273	__releases(RCU)
274	__releases(&msq->q_perm)
275{
276	struct msg_msg *msg, *t;
277	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
278	DEFINE_WAKE_Q(wake_q);
279
280	expunge_all(msq, -EIDRM, &wake_q);
281	ss_wakeup(msq, &wake_q, true);
282	msg_rmid(ns, msq);
283	ipc_unlock_object(&msq->q_perm);
284	wake_up_q(&wake_q);
285	rcu_read_unlock();
286
287	list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
288		atomic_dec(&ns->msg_hdrs);
289		free_msg(msg);
290	}
291	atomic_sub(msq->q_cbytes, &ns->msg_bytes);
292	ipc_update_pid(&msq->q_lspid, NULL);
293	ipc_update_pid(&msq->q_lrpid, NULL);
294	ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
295}
296
297long ksys_msgget(key_t key, int msgflg)
298{
299	struct ipc_namespace *ns;
300	static const struct ipc_ops msg_ops = {
301		.getnew = newque,
302		.associate = security_msg_queue_associate,
303	};
304	struct ipc_params msg_params;
305
306	ns = current->nsproxy->ipc_ns;
307
308	msg_params.key = key;
309	msg_params.flg = msgflg;
310
311	return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
312}
313
314SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
315{
316	return ksys_msgget(key, msgflg);
317}
318
319static inline unsigned long
320copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
321{
322	switch (version) {
323	case IPC_64:
324		return copy_to_user(buf, in, sizeof(*in));
325	case IPC_OLD:
326	{
327		struct msqid_ds out;
328
329		memset(&out, 0, sizeof(out));
330
331		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
332
333		out.msg_stime		= in->msg_stime;
334		out.msg_rtime		= in->msg_rtime;
335		out.msg_ctime		= in->msg_ctime;
336
337		if (in->msg_cbytes > USHRT_MAX)
338			out.msg_cbytes	= USHRT_MAX;
339		else
340			out.msg_cbytes	= in->msg_cbytes;
341		out.msg_lcbytes		= in->msg_cbytes;
342
343		if (in->msg_qnum > USHRT_MAX)
344			out.msg_qnum	= USHRT_MAX;
345		else
346			out.msg_qnum	= in->msg_qnum;
347
348		if (in->msg_qbytes > USHRT_MAX)
349			out.msg_qbytes	= USHRT_MAX;
350		else
351			out.msg_qbytes	= in->msg_qbytes;
352		out.msg_lqbytes		= in->msg_qbytes;
353
354		out.msg_lspid		= in->msg_lspid;
355		out.msg_lrpid		= in->msg_lrpid;
356
357		return copy_to_user(buf, &out, sizeof(out));
358	}
359	default:
360		return -EINVAL;
361	}
362}
363
364static inline unsigned long
365copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
366{
367	switch (version) {
368	case IPC_64:
369		if (copy_from_user(out, buf, sizeof(*out)))
370			return -EFAULT;
371		return 0;
372	case IPC_OLD:
373	{
374		struct msqid_ds tbuf_old;
375
376		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
377			return -EFAULT;
378
379		out->msg_perm.uid	= tbuf_old.msg_perm.uid;
380		out->msg_perm.gid	= tbuf_old.msg_perm.gid;
381		out->msg_perm.mode	= tbuf_old.msg_perm.mode;
382
383		if (tbuf_old.msg_qbytes == 0)
384			out->msg_qbytes	= tbuf_old.msg_lqbytes;
385		else
386			out->msg_qbytes	= tbuf_old.msg_qbytes;
387
388		return 0;
389	}
390	default:
391		return -EINVAL;
392	}
393}
394
395/*
396 * This function handles some msgctl commands which require the rwsem
397 * to be held in write mode.
398 * NOTE: no locks must be held, the rwsem is taken inside this function.
399 */
400static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
401			struct ipc64_perm *perm, int msg_qbytes)
402{
403	struct kern_ipc_perm *ipcp;
404	struct msg_queue *msq;
405	int err;
406
407	down_write(&msg_ids(ns).rwsem);
408	rcu_read_lock();
409
410	ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd,
411				      perm, msg_qbytes);
412	if (IS_ERR(ipcp)) {
413		err = PTR_ERR(ipcp);
414		goto out_unlock1;
415	}
416
417	msq = container_of(ipcp, struct msg_queue, q_perm);
418
419	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
420	if (err)
421		goto out_unlock1;
422
423	switch (cmd) {
424	case IPC_RMID:
425		ipc_lock_object(&msq->q_perm);
426		/* freeque unlocks the ipc object and rcu */
427		freeque(ns, ipcp);
428		goto out_up;
429	case IPC_SET:
430	{
431		DEFINE_WAKE_Q(wake_q);
432
433		if (msg_qbytes > ns->msg_ctlmnb &&
434		    !capable(CAP_SYS_RESOURCE)) {
435			err = -EPERM;
436			goto out_unlock1;
437		}
438
439		ipc_lock_object(&msq->q_perm);
440		err = ipc_update_perm(perm, ipcp);
441		if (err)
442			goto out_unlock0;
443
444		msq->q_qbytes = msg_qbytes;
445
446		msq->q_ctime = ktime_get_real_seconds();
447		/*
448		 * Sleeping receivers might be excluded by
449		 * stricter permissions.
450		 */
451		expunge_all(msq, -EAGAIN, &wake_q);
452		/*
453		 * Sleeping senders might be able to send
454		 * due to a larger queue size.
455		 */
456		ss_wakeup(msq, &wake_q, false);
457		ipc_unlock_object(&msq->q_perm);
458		wake_up_q(&wake_q);
459
460		goto out_unlock1;
461	}
462	default:
463		err = -EINVAL;
464		goto out_unlock1;
465	}
466
467out_unlock0:
468	ipc_unlock_object(&msq->q_perm);
469out_unlock1:
470	rcu_read_unlock();
471out_up:
472	up_write(&msg_ids(ns).rwsem);
473	return err;
474}
475
476static int msgctl_info(struct ipc_namespace *ns, int msqid,
477			 int cmd, struct msginfo *msginfo)
478{
479	int err;
480	int max_idx;
481
482	/*
483	 * We must not return kernel stack data.
484	 * due to padding, it's not enough
485	 * to set all member fields.
486	 */
487	err = security_msg_queue_msgctl(NULL, cmd);
488	if (err)
489		return err;
490
491	memset(msginfo, 0, sizeof(*msginfo));
492	msginfo->msgmni = ns->msg_ctlmni;
493	msginfo->msgmax = ns->msg_ctlmax;
494	msginfo->msgmnb = ns->msg_ctlmnb;
495	msginfo->msgssz = MSGSSZ;
496	msginfo->msgseg = MSGSEG;
497	down_read(&msg_ids(ns).rwsem);
498	if (cmd == MSG_INFO) {
499		msginfo->msgpool = msg_ids(ns).in_use;
500		msginfo->msgmap = atomic_read(&ns->msg_hdrs);
501		msginfo->msgtql = atomic_read(&ns->msg_bytes);
502	} else {
503		msginfo->msgmap = MSGMAP;
504		msginfo->msgpool = MSGPOOL;
505		msginfo->msgtql = MSGTQL;
506	}
507	max_idx = ipc_get_maxidx(&msg_ids(ns));
508	up_read(&msg_ids(ns).rwsem);
509	return (max_idx < 0) ? 0 : max_idx;
510}
511
512static int msgctl_stat(struct ipc_namespace *ns, int msqid,
513			 int cmd, struct msqid64_ds *p)
514{
515	struct msg_queue *msq;
516	int err;
517
518	memset(p, 0, sizeof(*p));
519
520	rcu_read_lock();
521	if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
522		msq = msq_obtain_object(ns, msqid);
523		if (IS_ERR(msq)) {
524			err = PTR_ERR(msq);
525			goto out_unlock;
526		}
527	} else { /* IPC_STAT */
528		msq = msq_obtain_object_check(ns, msqid);
529		if (IS_ERR(msq)) {
530			err = PTR_ERR(msq);
531			goto out_unlock;
532		}
533	}
534
535	/* see comment for SHM_STAT_ANY */
536	if (cmd == MSG_STAT_ANY)
537		audit_ipc_obj(&msq->q_perm);
538	else {
539		err = -EACCES;
540		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
541			goto out_unlock;
542	}
543
544	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
545	if (err)
546		goto out_unlock;
547
548	ipc_lock_object(&msq->q_perm);
549
550	if (!ipc_valid_object(&msq->q_perm)) {
551		ipc_unlock_object(&msq->q_perm);
552		err = -EIDRM;
553		goto out_unlock;
554	}
555
556	kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
557	p->msg_stime  = msq->q_stime;
558	p->msg_rtime  = msq->q_rtime;
559	p->msg_ctime  = msq->q_ctime;
560#ifndef CONFIG_64BIT
561	p->msg_stime_high = msq->q_stime >> 32;
562	p->msg_rtime_high = msq->q_rtime >> 32;
563	p->msg_ctime_high = msq->q_ctime >> 32;
564#endif
565	p->msg_cbytes = msq->q_cbytes;
566	p->msg_qnum   = msq->q_qnum;
567	p->msg_qbytes = msq->q_qbytes;
568	p->msg_lspid  = pid_vnr(msq->q_lspid);
569	p->msg_lrpid  = pid_vnr(msq->q_lrpid);
570
571	if (cmd == IPC_STAT) {
572		/*
573		 * As defined in SUS:
574		 * Return 0 on success
575		 */
576		err = 0;
577	} else {
578		/*
579		 * MSG_STAT and MSG_STAT_ANY (both Linux specific)
580		 * Return the full id, including the sequence number
581		 */
582		err = msq->q_perm.id;
583	}
584
585	ipc_unlock_object(&msq->q_perm);
586out_unlock:
587	rcu_read_unlock();
588	return err;
589}
590
591static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version)
592{
593	struct ipc_namespace *ns;
594	struct msqid64_ds msqid64;
595	int err;
596
597	if (msqid < 0 || cmd < 0)
598		return -EINVAL;
599
600	ns = current->nsproxy->ipc_ns;
601
602	switch (cmd) {
603	case IPC_INFO:
604	case MSG_INFO: {
605		struct msginfo msginfo;
606		err = msgctl_info(ns, msqid, cmd, &msginfo);
607		if (err < 0)
608			return err;
609		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
610			err = -EFAULT;
611		return err;
612	}
613	case MSG_STAT:	/* msqid is an index rather than a msg queue id */
614	case MSG_STAT_ANY:
615	case IPC_STAT:
616		err = msgctl_stat(ns, msqid, cmd, &msqid64);
617		if (err < 0)
618			return err;
619		if (copy_msqid_to_user(buf, &msqid64, version))
620			err = -EFAULT;
621		return err;
622	case IPC_SET:
623		if (copy_msqid_from_user(&msqid64, buf, version))
624			return -EFAULT;
625		return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm,
626				   msqid64.msg_qbytes);
627	case IPC_RMID:
628		return msgctl_down(ns, msqid, cmd, NULL, 0);
629	default:
630		return  -EINVAL;
631	}
632}
633
634SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
635{
636	return ksys_msgctl(msqid, cmd, buf, IPC_64);
637}
638
639#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
640long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
641{
642	int version = ipc_parse_version(&cmd);
643
644	return ksys_msgctl(msqid, cmd, buf, version);
645}
646
647SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
648{
649	return ksys_old_msgctl(msqid, cmd, buf);
650}
651#endif
652
653#ifdef CONFIG_COMPAT
654
655struct compat_msqid_ds {
656	struct compat_ipc_perm msg_perm;
657	compat_uptr_t msg_first;
658	compat_uptr_t msg_last;
659	old_time32_t msg_stime;
660	old_time32_t msg_rtime;
661	old_time32_t msg_ctime;
662	compat_ulong_t msg_lcbytes;
663	compat_ulong_t msg_lqbytes;
664	unsigned short msg_cbytes;
665	unsigned short msg_qnum;
666	unsigned short msg_qbytes;
667	compat_ipc_pid_t msg_lspid;
668	compat_ipc_pid_t msg_lrpid;
669};
670
671static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
672					int version)
673{
674	memset(out, 0, sizeof(*out));
675	if (version == IPC_64) {
676		struct compat_msqid64_ds __user *p = buf;
677		if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
678			return -EFAULT;
679		if (get_user(out->msg_qbytes, &p->msg_qbytes))
680			return -EFAULT;
681	} else {
682		struct compat_msqid_ds __user *p = buf;
683		if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
684			return -EFAULT;
685		if (get_user(out->msg_qbytes, &p->msg_qbytes))
686			return -EFAULT;
687	}
688	return 0;
689}
690
691static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
692					int version)
693{
694	if (version == IPC_64) {
695		struct compat_msqid64_ds v;
696		memset(&v, 0, sizeof(v));
697		to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
698		v.msg_stime	 = lower_32_bits(in->msg_stime);
699		v.msg_stime_high = upper_32_bits(in->msg_stime);
700		v.msg_rtime	 = lower_32_bits(in->msg_rtime);
701		v.msg_rtime_high = upper_32_bits(in->msg_rtime);
702		v.msg_ctime	 = lower_32_bits(in->msg_ctime);
703		v.msg_ctime_high = upper_32_bits(in->msg_ctime);
704		v.msg_cbytes = in->msg_cbytes;
705		v.msg_qnum = in->msg_qnum;
706		v.msg_qbytes = in->msg_qbytes;
707		v.msg_lspid = in->msg_lspid;
708		v.msg_lrpid = in->msg_lrpid;
709		return copy_to_user(buf, &v, sizeof(v));
710	} else {
711		struct compat_msqid_ds v;
712		memset(&v, 0, sizeof(v));
713		to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
714		v.msg_stime = in->msg_stime;
715		v.msg_rtime = in->msg_rtime;
716		v.msg_ctime = in->msg_ctime;
717		v.msg_cbytes = in->msg_cbytes;
718		v.msg_qnum = in->msg_qnum;
719		v.msg_qbytes = in->msg_qbytes;
720		v.msg_lspid = in->msg_lspid;
721		v.msg_lrpid = in->msg_lrpid;
722		return copy_to_user(buf, &v, sizeof(v));
723	}
724}
725
726static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version)
727{
728	struct ipc_namespace *ns;
729	int err;
730	struct msqid64_ds msqid64;
731
732	ns = current->nsproxy->ipc_ns;
733
734	if (msqid < 0 || cmd < 0)
735		return -EINVAL;
736
737	switch (cmd & (~IPC_64)) {
738	case IPC_INFO:
739	case MSG_INFO: {
740		struct msginfo msginfo;
741		err = msgctl_info(ns, msqid, cmd, &msginfo);
742		if (err < 0)
743			return err;
744		if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
745			err = -EFAULT;
746		return err;
747	}
748	case IPC_STAT:
749	case MSG_STAT:
750	case MSG_STAT_ANY:
751		err = msgctl_stat(ns, msqid, cmd, &msqid64);
752		if (err < 0)
753			return err;
754		if (copy_compat_msqid_to_user(uptr, &msqid64, version))
755			err = -EFAULT;
756		return err;
757	case IPC_SET:
758		if (copy_compat_msqid_from_user(&msqid64, uptr, version))
759			return -EFAULT;
760		return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes);
761	case IPC_RMID:
762		return msgctl_down(ns, msqid, cmd, NULL, 0);
763	default:
764		return -EINVAL;
765	}
766}
767
768COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
769{
770	return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64);
771}
772
773#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
774long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr)
775{
776	int version = compat_ipc_parse_version(&cmd);
777
778	return compat_ksys_msgctl(msqid, cmd, uptr, version);
779}
780
781COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr)
782{
783	return compat_ksys_old_msgctl(msqid, cmd, uptr);
784}
785#endif
786#endif
787
788static int testmsg(struct msg_msg *msg, long type, int mode)
789{
790	switch (mode) {
791	case SEARCH_ANY:
792	case SEARCH_NUMBER:
793		return 1;
794	case SEARCH_LESSEQUAL:
795		if (msg->m_type <= type)
796			return 1;
797		break;
798	case SEARCH_EQUAL:
799		if (msg->m_type == type)
800			return 1;
801		break;
802	case SEARCH_NOTEQUAL:
803		if (msg->m_type != type)
804			return 1;
805		break;
806	}
807	return 0;
808}
809
810static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
811				 struct wake_q_head *wake_q)
812{
813	struct msg_receiver *msr, *t;
814
815	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
816		if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
817		    !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk,
818					       msr->r_msgtype, msr->r_mode)) {
819
820			list_del(&msr->r_list);
821			if (msr->r_maxsize < msg->m_ts) {
822				wake_q_add(wake_q, msr->r_tsk);
823
824				/* See expunge_all regarding memory barrier */
825				smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG));
826			} else {
827				ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
828				msq->q_rtime = ktime_get_real_seconds();
829
830				wake_q_add(wake_q, msr->r_tsk);
831
832				/* See expunge_all regarding memory barrier */
833				smp_store_release(&msr->r_msg, msg);
834				return 1;
835			}
836		}
837	}
838
839	return 0;
840}
841
842static long do_msgsnd(int msqid, long mtype, void __user *mtext,
843		size_t msgsz, int msgflg)
844{
845	struct msg_queue *msq;
846	struct msg_msg *msg;
847	int err;
848	struct ipc_namespace *ns;
849	DEFINE_WAKE_Q(wake_q);
850
851	ns = current->nsproxy->ipc_ns;
852
853	if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
854		return -EINVAL;
855	if (mtype < 1)
856		return -EINVAL;
857
858	msg = load_msg(mtext, msgsz);
859	if (IS_ERR(msg))
860		return PTR_ERR(msg);
861
862	msg->m_type = mtype;
863	msg->m_ts = msgsz;
864
865	rcu_read_lock();
866	msq = msq_obtain_object_check(ns, msqid);
867	if (IS_ERR(msq)) {
868		err = PTR_ERR(msq);
869		goto out_unlock1;
870	}
871
872	ipc_lock_object(&msq->q_perm);
873
874	for (;;) {
875		struct msg_sender s;
876
877		err = -EACCES;
878		if (ipcperms(ns, &msq->q_perm, S_IWUGO))
879			goto out_unlock0;
880
881		/* raced with RMID? */
882		if (!ipc_valid_object(&msq->q_perm)) {
883			err = -EIDRM;
884			goto out_unlock0;
885		}
886
887		err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg);
888		if (err)
889			goto out_unlock0;
890
891		if (msg_fits_inqueue(msq, msgsz))
892			break;
893
894		/* queue full, wait: */
895		if (msgflg & IPC_NOWAIT) {
896			err = -EAGAIN;
897			goto out_unlock0;
898		}
899
900		/* enqueue the sender and prepare to block */
901		ss_add(msq, &s, msgsz);
902
903		if (!ipc_rcu_getref(&msq->q_perm)) {
904			err = -EIDRM;
905			goto out_unlock0;
906		}
907
908		ipc_unlock_object(&msq->q_perm);
909		rcu_read_unlock();
910		schedule();
911
912		rcu_read_lock();
913		ipc_lock_object(&msq->q_perm);
914
915		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
916		/* raced with RMID? */
917		if (!ipc_valid_object(&msq->q_perm)) {
918			err = -EIDRM;
919			goto out_unlock0;
920		}
921		ss_del(&s);
922
923		if (signal_pending(current)) {
924			err = -ERESTARTNOHAND;
925			goto out_unlock0;
926		}
927
928	}
929
930	ipc_update_pid(&msq->q_lspid, task_tgid(current));
931	msq->q_stime = ktime_get_real_seconds();
932
933	if (!pipelined_send(msq, msg, &wake_q)) {
934		/* no one is waiting for this message, enqueue it */
935		list_add_tail(&msg->m_list, &msq->q_messages);
936		msq->q_cbytes += msgsz;
937		msq->q_qnum++;
938		atomic_add(msgsz, &ns->msg_bytes);
939		atomic_inc(&ns->msg_hdrs);
940	}
941
942	err = 0;
943	msg = NULL;
944
945out_unlock0:
946	ipc_unlock_object(&msq->q_perm);
947	wake_up_q(&wake_q);
948out_unlock1:
949	rcu_read_unlock();
950	if (msg != NULL)
951		free_msg(msg);
952	return err;
953}
954
955long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
956		 int msgflg)
957{
958	long mtype;
959
960	if (get_user(mtype, &msgp->mtype))
961		return -EFAULT;
962	return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
963}
964
965SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
966		int, msgflg)
967{
968	return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
969}
970
971#ifdef CONFIG_COMPAT
972
973struct compat_msgbuf {
974	compat_long_t mtype;
975	char mtext[1];
976};
977
978long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
979		       compat_ssize_t msgsz, int msgflg)
980{
981	struct compat_msgbuf __user *up = compat_ptr(msgp);
982	compat_long_t mtype;
983
984	if (get_user(mtype, &up->mtype))
985		return -EFAULT;
986	return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
987}
988
989COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
990		       compat_ssize_t, msgsz, int, msgflg)
991{
992	return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
993}
994#endif
995
996static inline int convert_mode(long *msgtyp, int msgflg)
997{
998	if (msgflg & MSG_COPY)
999		return SEARCH_NUMBER;
1000	/*
1001	 *  find message of correct type.
1002	 *  msgtyp = 0 => get first.
1003	 *  msgtyp > 0 => get first message of matching type.
1004	 *  msgtyp < 0 => get message with least type must be < abs(msgtype).
1005	 */
1006	if (*msgtyp == 0)
1007		return SEARCH_ANY;
1008	if (*msgtyp < 0) {
1009		if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
1010			*msgtyp = LONG_MAX;
1011		else
1012			*msgtyp = -*msgtyp;
1013		return SEARCH_LESSEQUAL;
1014	}
1015	if (msgflg & MSG_EXCEPT)
1016		return SEARCH_NOTEQUAL;
1017	return SEARCH_EQUAL;
1018}
1019
1020static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1021{
1022	struct msgbuf __user *msgp = dest;
1023	size_t msgsz;
1024
1025	if (put_user(msg->m_type, &msgp->mtype))
1026		return -EFAULT;
1027
1028	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1029	if (store_msg(msgp->mtext, msg, msgsz))
1030		return -EFAULT;
1031	return msgsz;
1032}
1033
1034#ifdef CONFIG_CHECKPOINT_RESTORE
1035/*
1036 * This function creates new kernel message structure, large enough to store
1037 * bufsz message bytes.
1038 */
1039static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1040{
1041	struct msg_msg *copy;
1042
1043	/*
1044	 * Create dummy message to copy real message to.
1045	 */
1046	copy = load_msg(buf, bufsz);
1047	if (!IS_ERR(copy))
1048		copy->m_ts = bufsz;
1049	return copy;
1050}
1051
1052static inline void free_copy(struct msg_msg *copy)
1053{
1054	if (copy)
1055		free_msg(copy);
1056}
1057#else
1058static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1059{
1060	return ERR_PTR(-ENOSYS);
1061}
1062
1063static inline void free_copy(struct msg_msg *copy)
1064{
1065}
1066#endif
1067
1068static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
1069{
1070	struct msg_msg *msg, *found = NULL;
1071	long count = 0;
1072
1073	list_for_each_entry(msg, &msq->q_messages, m_list) {
1074		if (testmsg(msg, *msgtyp, mode) &&
1075		    !security_msg_queue_msgrcv(&msq->q_perm, msg, current,
1076					       *msgtyp, mode)) {
1077			if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
1078				*msgtyp = msg->m_type - 1;
1079				found = msg;
1080			} else if (mode == SEARCH_NUMBER) {
1081				if (*msgtyp == count)
1082					return msg;
1083			} else
1084				return msg;
1085			count++;
1086		}
1087	}
1088
1089	return found ?: ERR_PTR(-EAGAIN);
1090}
1091
1092static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
1093	       long (*msg_handler)(void __user *, struct msg_msg *, size_t))
1094{
1095	int mode;
1096	struct msg_queue *msq;
1097	struct ipc_namespace *ns;
1098	struct msg_msg *msg, *copy = NULL;
1099	DEFINE_WAKE_Q(wake_q);
1100
1101	ns = current->nsproxy->ipc_ns;
1102
1103	if (msqid < 0 || (long) bufsz < 0)
1104		return -EINVAL;
1105
1106	if (msgflg & MSG_COPY) {
1107		if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
1108			return -EINVAL;
1109		copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
1110		if (IS_ERR(copy))
1111			return PTR_ERR(copy);
1112	}
1113	mode = convert_mode(&msgtyp, msgflg);
1114
1115	rcu_read_lock();
1116	msq = msq_obtain_object_check(ns, msqid);
1117	if (IS_ERR(msq)) {
1118		rcu_read_unlock();
1119		free_copy(copy);
1120		return PTR_ERR(msq);
1121	}
1122
1123	for (;;) {
1124		struct msg_receiver msr_d;
1125
1126		msg = ERR_PTR(-EACCES);
1127		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1128			goto out_unlock1;
1129
1130		ipc_lock_object(&msq->q_perm);
1131
1132		/* raced with RMID? */
1133		if (!ipc_valid_object(&msq->q_perm)) {
1134			msg = ERR_PTR(-EIDRM);
1135			goto out_unlock0;
1136		}
1137
1138		msg = find_msg(msq, &msgtyp, mode);
1139		if (!IS_ERR(msg)) {
1140			/*
1141			 * Found a suitable message.
1142			 * Unlink it from the queue.
1143			 */
1144			if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1145				msg = ERR_PTR(-E2BIG);
1146				goto out_unlock0;
1147			}
1148			/*
1149			 * If we are copying, then do not unlink message and do
1150			 * not update queue parameters.
1151			 */
1152			if (msgflg & MSG_COPY) {
1153				msg = copy_msg(msg, copy);
1154				goto out_unlock0;
1155			}
1156
1157			list_del(&msg->m_list);
1158			msq->q_qnum--;
1159			msq->q_rtime = ktime_get_real_seconds();
1160			ipc_update_pid(&msq->q_lrpid, task_tgid(current));
1161			msq->q_cbytes -= msg->m_ts;
1162			atomic_sub(msg->m_ts, &ns->msg_bytes);
1163			atomic_dec(&ns->msg_hdrs);
1164			ss_wakeup(msq, &wake_q, false);
1165
1166			goto out_unlock0;
1167		}
1168
1169		/* No message waiting. Wait for a message */
1170		if (msgflg & IPC_NOWAIT) {
1171			msg = ERR_PTR(-ENOMSG);
1172			goto out_unlock0;
1173		}
1174
1175		list_add_tail(&msr_d.r_list, &msq->q_receivers);
1176		msr_d.r_tsk = current;
1177		msr_d.r_msgtype = msgtyp;
1178		msr_d.r_mode = mode;
1179		if (msgflg & MSG_NOERROR)
1180			msr_d.r_maxsize = INT_MAX;
1181		else
1182			msr_d.r_maxsize = bufsz;
1183
1184		/* memory barrier not require due to ipc_lock_object() */
1185		WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN));
1186
1187		/* memory barrier not required, we own ipc_lock_object() */
1188		__set_current_state(TASK_INTERRUPTIBLE);
1189
1190		ipc_unlock_object(&msq->q_perm);
1191		rcu_read_unlock();
1192		schedule();
1193
1194		/*
1195		 * Lockless receive, part 1:
1196		 * We don't hold a reference to the queue and getting a
1197		 * reference would defeat the idea of a lockless operation,
1198		 * thus the code relies on rcu to guarantee the existence of
1199		 * msq:
1200		 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1201		 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1202		 */
1203		rcu_read_lock();
1204
1205		/*
1206		 * Lockless receive, part 2:
1207		 * The work in pipelined_send() and expunge_all():
1208		 * - Set pointer to message
1209		 * - Queue the receiver task for later wakeup
1210		 * - Wake up the process after the lock is dropped.
1211		 *
1212		 * Should the process wake up before this wakeup (due to a
1213		 * signal) it will either see the message and continue ...
1214		 */
1215		msg = READ_ONCE(msr_d.r_msg);
1216		if (msg != ERR_PTR(-EAGAIN)) {
1217			/* see MSG_BARRIER for purpose/pairing */
1218			smp_acquire__after_ctrl_dep();
1219
1220			goto out_unlock1;
1221		}
1222
1223		 /*
1224		  * ... or see -EAGAIN, acquire the lock to check the message
1225		  * again.
1226		  */
1227		ipc_lock_object(&msq->q_perm);
1228
1229		msg = READ_ONCE(msr_d.r_msg);
1230		if (msg != ERR_PTR(-EAGAIN))
1231			goto out_unlock0;
1232
1233		list_del(&msr_d.r_list);
1234		if (signal_pending(current)) {
1235			msg = ERR_PTR(-ERESTARTNOHAND);
1236			goto out_unlock0;
1237		}
1238
1239		ipc_unlock_object(&msq->q_perm);
1240	}
1241
1242out_unlock0:
1243	ipc_unlock_object(&msq->q_perm);
1244	wake_up_q(&wake_q);
1245out_unlock1:
1246	rcu_read_unlock();
1247	if (IS_ERR(msg)) {
1248		free_copy(copy);
1249		return PTR_ERR(msg);
1250	}
1251
1252	bufsz = msg_handler(buf, msg, bufsz);
1253	free_msg(msg);
1254
1255	return bufsz;
1256}
1257
1258long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
1259		 long msgtyp, int msgflg)
1260{
1261	return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1262}
1263
1264SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1265		long, msgtyp, int, msgflg)
1266{
1267	return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1268}
1269
1270#ifdef CONFIG_COMPAT
1271static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1272{
1273	struct compat_msgbuf __user *msgp = dest;
1274	size_t msgsz;
1275
1276	if (put_user(msg->m_type, &msgp->mtype))
1277		return -EFAULT;
1278
1279	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1280	if (store_msg(msgp->mtext, msg, msgsz))
1281		return -EFAULT;
1282	return msgsz;
1283}
1284
1285long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
1286			compat_long_t msgtyp, int msgflg)
1287{
1288	return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1289			 msgflg, compat_do_msg_fill);
1290}
1291
1292COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1293		       compat_ssize_t, msgsz, compat_long_t, msgtyp,
1294		       int, msgflg)
1295{
1296	return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1297}
1298#endif
1299
1300void msg_init_ns(struct ipc_namespace *ns)
1301{
1302	ns->msg_ctlmax = MSGMAX;
1303	ns->msg_ctlmnb = MSGMNB;
1304	ns->msg_ctlmni = MSGMNI;
1305
1306	atomic_set(&ns->msg_bytes, 0);
1307	atomic_set(&ns->msg_hdrs, 0);
1308	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1309}
1310
1311#ifdef CONFIG_IPC_NS
1312void msg_exit_ns(struct ipc_namespace *ns)
1313{
1314	free_ipcs(ns, &msg_ids(ns), freeque);
1315	idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1316	rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1317}
1318#endif
1319
1320#ifdef CONFIG_PROC_FS
1321static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1322{
1323	struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1324	struct user_namespace *user_ns = seq_user_ns(s);
1325	struct kern_ipc_perm *ipcp = it;
1326	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1327
1328	seq_printf(s,
1329		   "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1330		   msq->q_perm.key,
1331		   msq->q_perm.id,
1332		   msq->q_perm.mode,
1333		   msq->q_cbytes,
1334		   msq->q_qnum,
1335		   pid_nr_ns(msq->q_lspid, pid_ns),
1336		   pid_nr_ns(msq->q_lrpid, pid_ns),
1337		   from_kuid_munged(user_ns, msq->q_perm.uid),
1338		   from_kgid_munged(user_ns, msq->q_perm.gid),
1339		   from_kuid_munged(user_ns, msq->q_perm.cuid),
1340		   from_kgid_munged(user_ns, msq->q_perm.cgid),
1341		   msq->q_stime,
1342		   msq->q_rtime,
1343		   msq->q_ctime);
1344
1345	return 0;
1346}
1347#endif
1348
1349void __init msg_init(void)
1350{
1351	msg_init_ns(&init_ipc_ns);
1352
1353	ipc_init_proc_interface("sysvipc/msg",
1354				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1355				IPC_MSG_IDS, sysvipc_msg_proc_show);
1356}
1357