msg.c revision 39cfffd7
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/* one msg_receiver structure for each sleeping receiver */
65struct msg_receiver {
66	struct list_head	r_list;
67	struct task_struct	*r_tsk;
68
69	int			r_mode;
70	long			r_msgtype;
71	long			r_maxsize;
72
73	struct msg_msg		*r_msg;
74};
75
76/* one msg_sender for each sleeping sender */
77struct msg_sender {
78	struct list_head	list;
79	struct task_struct	*tsk;
80	size_t                  msgsz;
81};
82
83#define SEARCH_ANY		1
84#define SEARCH_EQUAL		2
85#define SEARCH_NOTEQUAL		3
86#define SEARCH_LESSEQUAL	4
87#define SEARCH_NUMBER		5
88
89#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
90
91static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
92{
93	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id);
94
95	if (IS_ERR(ipcp))
96		return ERR_CAST(ipcp);
97
98	return container_of(ipcp, struct msg_queue, q_perm);
99}
100
101static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
102							int id)
103{
104	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
105
106	if (IS_ERR(ipcp))
107		return ERR_CAST(ipcp);
108
109	return container_of(ipcp, struct msg_queue, q_perm);
110}
111
112static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
113{
114	ipc_rmid(&msg_ids(ns), &s->q_perm);
115}
116
117static void msg_rcu_free(struct rcu_head *head)
118{
119	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
120	struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
121
122	security_msg_queue_free(&msq->q_perm);
123	kvfree(msq);
124}
125
126/**
127 * newque - Create a new msg queue
128 * @ns: namespace
129 * @params: ptr to the structure that contains the key and msgflg
130 *
131 * Called with msg_ids.rwsem held (writer)
132 */
133static int newque(struct ipc_namespace *ns, struct ipc_params *params)
134{
135	struct msg_queue *msq;
136	int retval;
137	key_t key = params->key;
138	int msgflg = params->flg;
139
140	msq = kvmalloc(sizeof(*msq), GFP_KERNEL);
141	if (unlikely(!msq))
142		return -ENOMEM;
143
144	msq->q_perm.mode = msgflg & S_IRWXUGO;
145	msq->q_perm.key = key;
146
147	msq->q_perm.security = NULL;
148	retval = security_msg_queue_alloc(&msq->q_perm);
149	if (retval) {
150		kvfree(msq);
151		return retval;
152	}
153
154	msq->q_stime = msq->q_rtime = 0;
155	msq->q_ctime = ktime_get_real_seconds();
156	msq->q_cbytes = msq->q_qnum = 0;
157	msq->q_qbytes = ns->msg_ctlmnb;
158	msq->q_lspid = msq->q_lrpid = NULL;
159	INIT_LIST_HEAD(&msq->q_messages);
160	INIT_LIST_HEAD(&msq->q_receivers);
161	INIT_LIST_HEAD(&msq->q_senders);
162
163	/* ipc_addid() locks msq upon success. */
164	retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
165	if (retval < 0) {
166		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
167		return retval;
168	}
169
170	ipc_unlock_object(&msq->q_perm);
171	rcu_read_unlock();
172
173	return msq->q_perm.id;
174}
175
176static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
177{
178	return msgsz + msq->q_cbytes <= msq->q_qbytes &&
179		1 + msq->q_qnum <= msq->q_qbytes;
180}
181
182static inline void ss_add(struct msg_queue *msq,
183			  struct msg_sender *mss, size_t msgsz)
184{
185	mss->tsk = current;
186	mss->msgsz = msgsz;
187	__set_current_state(TASK_INTERRUPTIBLE);
188	list_add_tail(&mss->list, &msq->q_senders);
189}
190
191static inline void ss_del(struct msg_sender *mss)
192{
193	if (mss->list.next)
194		list_del(&mss->list);
195}
196
197static void ss_wakeup(struct msg_queue *msq,
198		      struct wake_q_head *wake_q, bool kill)
199{
200	struct msg_sender *mss, *t;
201	struct task_struct *stop_tsk = NULL;
202	struct list_head *h = &msq->q_senders;
203
204	list_for_each_entry_safe(mss, t, h, list) {
205		if (kill)
206			mss->list.next = NULL;
207
208		/*
209		 * Stop at the first task we don't wakeup,
210		 * we've already iterated the original
211		 * sender queue.
212		 */
213		else if (stop_tsk == mss->tsk)
214			break;
215		/*
216		 * We are not in an EIDRM scenario here, therefore
217		 * verify that we really need to wakeup the task.
218		 * To maintain current semantics and wakeup order,
219		 * move the sender to the tail on behalf of the
220		 * blocked task.
221		 */
222		else if (!msg_fits_inqueue(msq, mss->msgsz)) {
223			if (!stop_tsk)
224				stop_tsk = mss->tsk;
225
226			list_move_tail(&mss->list, &msq->q_senders);
227			continue;
228		}
229
230		wake_q_add(wake_q, mss->tsk);
231	}
232}
233
234static void expunge_all(struct msg_queue *msq, int res,
235			struct wake_q_head *wake_q)
236{
237	struct msg_receiver *msr, *t;
238
239	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
240		wake_q_add(wake_q, msr->r_tsk);
241		WRITE_ONCE(msr->r_msg, ERR_PTR(res));
242	}
243}
244
245/*
246 * freeque() wakes up waiters on the sender and receiver waiting queue,
247 * removes the message queue from message queue ID IDR, and cleans up all the
248 * messages associated with this queue.
249 *
250 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
251 * before freeque() is called. msg_ids.rwsem remains locked on exit.
252 */
253static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
254{
255	struct msg_msg *msg, *t;
256	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
257	DEFINE_WAKE_Q(wake_q);
258
259	expunge_all(msq, -EIDRM, &wake_q);
260	ss_wakeup(msq, &wake_q, true);
261	msg_rmid(ns, msq);
262	ipc_unlock_object(&msq->q_perm);
263	wake_up_q(&wake_q);
264	rcu_read_unlock();
265
266	list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
267		atomic_dec(&ns->msg_hdrs);
268		free_msg(msg);
269	}
270	atomic_sub(msq->q_cbytes, &ns->msg_bytes);
271	ipc_update_pid(&msq->q_lspid, NULL);
272	ipc_update_pid(&msq->q_lrpid, NULL);
273	ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
274}
275
276long ksys_msgget(key_t key, int msgflg)
277{
278	struct ipc_namespace *ns;
279	static const struct ipc_ops msg_ops = {
280		.getnew = newque,
281		.associate = security_msg_queue_associate,
282	};
283	struct ipc_params msg_params;
284
285	ns = current->nsproxy->ipc_ns;
286
287	msg_params.key = key;
288	msg_params.flg = msgflg;
289
290	return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
291}
292
293SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
294{
295	return ksys_msgget(key, msgflg);
296}
297
298static inline unsigned long
299copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
300{
301	switch (version) {
302	case IPC_64:
303		return copy_to_user(buf, in, sizeof(*in));
304	case IPC_OLD:
305	{
306		struct msqid_ds out;
307
308		memset(&out, 0, sizeof(out));
309
310		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
311
312		out.msg_stime		= in->msg_stime;
313		out.msg_rtime		= in->msg_rtime;
314		out.msg_ctime		= in->msg_ctime;
315
316		if (in->msg_cbytes > USHRT_MAX)
317			out.msg_cbytes	= USHRT_MAX;
318		else
319			out.msg_cbytes	= in->msg_cbytes;
320		out.msg_lcbytes		= in->msg_cbytes;
321
322		if (in->msg_qnum > USHRT_MAX)
323			out.msg_qnum	= USHRT_MAX;
324		else
325			out.msg_qnum	= in->msg_qnum;
326
327		if (in->msg_qbytes > USHRT_MAX)
328			out.msg_qbytes	= USHRT_MAX;
329		else
330			out.msg_qbytes	= in->msg_qbytes;
331		out.msg_lqbytes		= in->msg_qbytes;
332
333		out.msg_lspid		= in->msg_lspid;
334		out.msg_lrpid		= in->msg_lrpid;
335
336		return copy_to_user(buf, &out, sizeof(out));
337	}
338	default:
339		return -EINVAL;
340	}
341}
342
343static inline unsigned long
344copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
345{
346	switch (version) {
347	case IPC_64:
348		if (copy_from_user(out, buf, sizeof(*out)))
349			return -EFAULT;
350		return 0;
351	case IPC_OLD:
352	{
353		struct msqid_ds tbuf_old;
354
355		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
356			return -EFAULT;
357
358		out->msg_perm.uid	= tbuf_old.msg_perm.uid;
359		out->msg_perm.gid	= tbuf_old.msg_perm.gid;
360		out->msg_perm.mode	= tbuf_old.msg_perm.mode;
361
362		if (tbuf_old.msg_qbytes == 0)
363			out->msg_qbytes	= tbuf_old.msg_lqbytes;
364		else
365			out->msg_qbytes	= tbuf_old.msg_qbytes;
366
367		return 0;
368	}
369	default:
370		return -EINVAL;
371	}
372}
373
374/*
375 * This function handles some msgctl commands which require the rwsem
376 * to be held in write mode.
377 * NOTE: no locks must be held, the rwsem is taken inside this function.
378 */
379static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
380			struct msqid64_ds *msqid64)
381{
382	struct kern_ipc_perm *ipcp;
383	struct msg_queue *msq;
384	int err;
385
386	down_write(&msg_ids(ns).rwsem);
387	rcu_read_lock();
388
389	ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
390				      &msqid64->msg_perm, msqid64->msg_qbytes);
391	if (IS_ERR(ipcp)) {
392		err = PTR_ERR(ipcp);
393		goto out_unlock1;
394	}
395
396	msq = container_of(ipcp, struct msg_queue, q_perm);
397
398	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
399	if (err)
400		goto out_unlock1;
401
402	switch (cmd) {
403	case IPC_RMID:
404		ipc_lock_object(&msq->q_perm);
405		/* freeque unlocks the ipc object and rcu */
406		freeque(ns, ipcp);
407		goto out_up;
408	case IPC_SET:
409	{
410		DEFINE_WAKE_Q(wake_q);
411
412		if (msqid64->msg_qbytes > ns->msg_ctlmnb &&
413		    !capable(CAP_SYS_RESOURCE)) {
414			err = -EPERM;
415			goto out_unlock1;
416		}
417
418		ipc_lock_object(&msq->q_perm);
419		err = ipc_update_perm(&msqid64->msg_perm, ipcp);
420		if (err)
421			goto out_unlock0;
422
423		msq->q_qbytes = msqid64->msg_qbytes;
424
425		msq->q_ctime = ktime_get_real_seconds();
426		/*
427		 * Sleeping receivers might be excluded by
428		 * stricter permissions.
429		 */
430		expunge_all(msq, -EAGAIN, &wake_q);
431		/*
432		 * Sleeping senders might be able to send
433		 * due to a larger queue size.
434		 */
435		ss_wakeup(msq, &wake_q, false);
436		ipc_unlock_object(&msq->q_perm);
437		wake_up_q(&wake_q);
438
439		goto out_unlock1;
440	}
441	default:
442		err = -EINVAL;
443		goto out_unlock1;
444	}
445
446out_unlock0:
447	ipc_unlock_object(&msq->q_perm);
448out_unlock1:
449	rcu_read_unlock();
450out_up:
451	up_write(&msg_ids(ns).rwsem);
452	return err;
453}
454
455static int msgctl_info(struct ipc_namespace *ns, int msqid,
456			 int cmd, struct msginfo *msginfo)
457{
458	int err;
459	int max_id;
460
461	/*
462	 * We must not return kernel stack data.
463	 * due to padding, it's not enough
464	 * to set all member fields.
465	 */
466	err = security_msg_queue_msgctl(NULL, cmd);
467	if (err)
468		return err;
469
470	memset(msginfo, 0, sizeof(*msginfo));
471	msginfo->msgmni = ns->msg_ctlmni;
472	msginfo->msgmax = ns->msg_ctlmax;
473	msginfo->msgmnb = ns->msg_ctlmnb;
474	msginfo->msgssz = MSGSSZ;
475	msginfo->msgseg = MSGSEG;
476	down_read(&msg_ids(ns).rwsem);
477	if (cmd == MSG_INFO) {
478		msginfo->msgpool = msg_ids(ns).in_use;
479		msginfo->msgmap = atomic_read(&ns->msg_hdrs);
480		msginfo->msgtql = atomic_read(&ns->msg_bytes);
481	} else {
482		msginfo->msgmap = MSGMAP;
483		msginfo->msgpool = MSGPOOL;
484		msginfo->msgtql = MSGTQL;
485	}
486	max_id = ipc_get_maxid(&msg_ids(ns));
487	up_read(&msg_ids(ns).rwsem);
488	return (max_id < 0) ? 0 : max_id;
489}
490
491static int msgctl_stat(struct ipc_namespace *ns, int msqid,
492			 int cmd, struct msqid64_ds *p)
493{
494	struct msg_queue *msq;
495	int err;
496
497	memset(p, 0, sizeof(*p));
498
499	rcu_read_lock();
500	if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
501		msq = msq_obtain_object(ns, msqid);
502		if (IS_ERR(msq)) {
503			err = PTR_ERR(msq);
504			goto out_unlock;
505		}
506	} else { /* IPC_STAT */
507		msq = msq_obtain_object_check(ns, msqid);
508		if (IS_ERR(msq)) {
509			err = PTR_ERR(msq);
510			goto out_unlock;
511		}
512	}
513
514	/* see comment for SHM_STAT_ANY */
515	if (cmd == MSG_STAT_ANY)
516		audit_ipc_obj(&msq->q_perm);
517	else {
518		err = -EACCES;
519		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
520			goto out_unlock;
521	}
522
523	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
524	if (err)
525		goto out_unlock;
526
527	ipc_lock_object(&msq->q_perm);
528
529	if (!ipc_valid_object(&msq->q_perm)) {
530		ipc_unlock_object(&msq->q_perm);
531		err = -EIDRM;
532		goto out_unlock;
533	}
534
535	kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
536	p->msg_stime  = msq->q_stime;
537	p->msg_rtime  = msq->q_rtime;
538	p->msg_ctime  = msq->q_ctime;
539#ifndef CONFIG_64BIT
540	p->msg_stime_high = msq->q_stime >> 32;
541	p->msg_rtime_high = msq->q_rtime >> 32;
542	p->msg_ctime_high = msq->q_ctime >> 32;
543#endif
544	p->msg_cbytes = msq->q_cbytes;
545	p->msg_qnum   = msq->q_qnum;
546	p->msg_qbytes = msq->q_qbytes;
547	p->msg_lspid  = pid_vnr(msq->q_lspid);
548	p->msg_lrpid  = pid_vnr(msq->q_lrpid);
549
550	if (cmd == IPC_STAT) {
551		/*
552		 * As defined in SUS:
553		 * Return 0 on success
554		 */
555		err = 0;
556	} else {
557		/*
558		 * MSG_STAT and MSG_STAT_ANY (both Linux specific)
559		 * Return the full id, including the sequence number
560		 */
561		err = msq->q_perm.id;
562	}
563
564	ipc_unlock_object(&msq->q_perm);
565out_unlock:
566	rcu_read_unlock();
567	return err;
568}
569
570long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
571{
572	int version;
573	struct ipc_namespace *ns;
574	struct msqid64_ds msqid64;
575	int err;
576
577	if (msqid < 0 || cmd < 0)
578		return -EINVAL;
579
580	version = ipc_parse_version(&cmd);
581	ns = current->nsproxy->ipc_ns;
582
583	switch (cmd) {
584	case IPC_INFO:
585	case MSG_INFO: {
586		struct msginfo msginfo;
587		err = msgctl_info(ns, msqid, cmd, &msginfo);
588		if (err < 0)
589			return err;
590		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
591			err = -EFAULT;
592		return err;
593	}
594	case MSG_STAT:	/* msqid is an index rather than a msg queue id */
595	case MSG_STAT_ANY:
596	case IPC_STAT:
597		err = msgctl_stat(ns, msqid, cmd, &msqid64);
598		if (err < 0)
599			return err;
600		if (copy_msqid_to_user(buf, &msqid64, version))
601			err = -EFAULT;
602		return err;
603	case IPC_SET:
604		if (copy_msqid_from_user(&msqid64, buf, version))
605			return -EFAULT;
606		/* fallthru */
607	case IPC_RMID:
608		return msgctl_down(ns, msqid, cmd, &msqid64);
609	default:
610		return  -EINVAL;
611	}
612}
613
614SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
615{
616	return ksys_msgctl(msqid, cmd, buf);
617}
618
619#ifdef CONFIG_COMPAT
620
621struct compat_msqid_ds {
622	struct compat_ipc_perm msg_perm;
623	compat_uptr_t msg_first;
624	compat_uptr_t msg_last;
625	compat_time_t msg_stime;
626	compat_time_t msg_rtime;
627	compat_time_t msg_ctime;
628	compat_ulong_t msg_lcbytes;
629	compat_ulong_t msg_lqbytes;
630	unsigned short msg_cbytes;
631	unsigned short msg_qnum;
632	unsigned short msg_qbytes;
633	compat_ipc_pid_t msg_lspid;
634	compat_ipc_pid_t msg_lrpid;
635};
636
637static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
638					int version)
639{
640	memset(out, 0, sizeof(*out));
641	if (version == IPC_64) {
642		struct compat_msqid64_ds __user *p = buf;
643		if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
644			return -EFAULT;
645		if (get_user(out->msg_qbytes, &p->msg_qbytes))
646			return -EFAULT;
647	} else {
648		struct compat_msqid_ds __user *p = buf;
649		if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
650			return -EFAULT;
651		if (get_user(out->msg_qbytes, &p->msg_qbytes))
652			return -EFAULT;
653	}
654	return 0;
655}
656
657static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
658					int version)
659{
660	if (version == IPC_64) {
661		struct compat_msqid64_ds v;
662		memset(&v, 0, sizeof(v));
663		to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
664		v.msg_stime	 = lower_32_bits(in->msg_stime);
665		v.msg_stime_high = upper_32_bits(in->msg_stime);
666		v.msg_rtime	 = lower_32_bits(in->msg_rtime);
667		v.msg_rtime_high = upper_32_bits(in->msg_rtime);
668		v.msg_ctime	 = lower_32_bits(in->msg_ctime);
669		v.msg_ctime_high = upper_32_bits(in->msg_ctime);
670		v.msg_cbytes = in->msg_cbytes;
671		v.msg_qnum = in->msg_qnum;
672		v.msg_qbytes = in->msg_qbytes;
673		v.msg_lspid = in->msg_lspid;
674		v.msg_lrpid = in->msg_lrpid;
675		return copy_to_user(buf, &v, sizeof(v));
676	} else {
677		struct compat_msqid_ds v;
678		memset(&v, 0, sizeof(v));
679		to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
680		v.msg_stime = in->msg_stime;
681		v.msg_rtime = in->msg_rtime;
682		v.msg_ctime = in->msg_ctime;
683		v.msg_cbytes = in->msg_cbytes;
684		v.msg_qnum = in->msg_qnum;
685		v.msg_qbytes = in->msg_qbytes;
686		v.msg_lspid = in->msg_lspid;
687		v.msg_lrpid = in->msg_lrpid;
688		return copy_to_user(buf, &v, sizeof(v));
689	}
690}
691
692long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr)
693{
694	struct ipc_namespace *ns;
695	int err;
696	struct msqid64_ds msqid64;
697	int version = compat_ipc_parse_version(&cmd);
698
699	ns = current->nsproxy->ipc_ns;
700
701	if (msqid < 0 || cmd < 0)
702		return -EINVAL;
703
704	switch (cmd & (~IPC_64)) {
705	case IPC_INFO:
706	case MSG_INFO: {
707		struct msginfo msginfo;
708		err = msgctl_info(ns, msqid, cmd, &msginfo);
709		if (err < 0)
710			return err;
711		if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
712			err = -EFAULT;
713		return err;
714	}
715	case IPC_STAT:
716	case MSG_STAT:
717	case MSG_STAT_ANY:
718		err = msgctl_stat(ns, msqid, cmd, &msqid64);
719		if (err < 0)
720			return err;
721		if (copy_compat_msqid_to_user(uptr, &msqid64, version))
722			err = -EFAULT;
723		return err;
724	case IPC_SET:
725		if (copy_compat_msqid_from_user(&msqid64, uptr, version))
726			return -EFAULT;
727		/* fallthru */
728	case IPC_RMID:
729		return msgctl_down(ns, msqid, cmd, &msqid64);
730	default:
731		return -EINVAL;
732	}
733}
734
735COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
736{
737	return compat_ksys_msgctl(msqid, cmd, uptr);
738}
739#endif
740
741static int testmsg(struct msg_msg *msg, long type, int mode)
742{
743	switch (mode) {
744	case SEARCH_ANY:
745	case SEARCH_NUMBER:
746		return 1;
747	case SEARCH_LESSEQUAL:
748		if (msg->m_type <= type)
749			return 1;
750		break;
751	case SEARCH_EQUAL:
752		if (msg->m_type == type)
753			return 1;
754		break;
755	case SEARCH_NOTEQUAL:
756		if (msg->m_type != type)
757			return 1;
758		break;
759	}
760	return 0;
761}
762
763static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
764				 struct wake_q_head *wake_q)
765{
766	struct msg_receiver *msr, *t;
767
768	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
769		if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
770		    !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk,
771					       msr->r_msgtype, msr->r_mode)) {
772
773			list_del(&msr->r_list);
774			if (msr->r_maxsize < msg->m_ts) {
775				wake_q_add(wake_q, msr->r_tsk);
776				WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG));
777			} else {
778				ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
779				msq->q_rtime = ktime_get_real_seconds();
780
781				wake_q_add(wake_q, msr->r_tsk);
782				WRITE_ONCE(msr->r_msg, msg);
783				return 1;
784			}
785		}
786	}
787
788	return 0;
789}
790
791static long do_msgsnd(int msqid, long mtype, void __user *mtext,
792		size_t msgsz, int msgflg)
793{
794	struct msg_queue *msq;
795	struct msg_msg *msg;
796	int err;
797	struct ipc_namespace *ns;
798	DEFINE_WAKE_Q(wake_q);
799
800	ns = current->nsproxy->ipc_ns;
801
802	if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
803		return -EINVAL;
804	if (mtype < 1)
805		return -EINVAL;
806
807	msg = load_msg(mtext, msgsz);
808	if (IS_ERR(msg))
809		return PTR_ERR(msg);
810
811	msg->m_type = mtype;
812	msg->m_ts = msgsz;
813
814	rcu_read_lock();
815	msq = msq_obtain_object_check(ns, msqid);
816	if (IS_ERR(msq)) {
817		err = PTR_ERR(msq);
818		goto out_unlock1;
819	}
820
821	ipc_lock_object(&msq->q_perm);
822
823	for (;;) {
824		struct msg_sender s;
825
826		err = -EACCES;
827		if (ipcperms(ns, &msq->q_perm, S_IWUGO))
828			goto out_unlock0;
829
830		/* raced with RMID? */
831		if (!ipc_valid_object(&msq->q_perm)) {
832			err = -EIDRM;
833			goto out_unlock0;
834		}
835
836		err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg);
837		if (err)
838			goto out_unlock0;
839
840		if (msg_fits_inqueue(msq, msgsz))
841			break;
842
843		/* queue full, wait: */
844		if (msgflg & IPC_NOWAIT) {
845			err = -EAGAIN;
846			goto out_unlock0;
847		}
848
849		/* enqueue the sender and prepare to block */
850		ss_add(msq, &s, msgsz);
851
852		if (!ipc_rcu_getref(&msq->q_perm)) {
853			err = -EIDRM;
854			goto out_unlock0;
855		}
856
857		ipc_unlock_object(&msq->q_perm);
858		rcu_read_unlock();
859		schedule();
860
861		rcu_read_lock();
862		ipc_lock_object(&msq->q_perm);
863
864		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
865		/* raced with RMID? */
866		if (!ipc_valid_object(&msq->q_perm)) {
867			err = -EIDRM;
868			goto out_unlock0;
869		}
870		ss_del(&s);
871
872		if (signal_pending(current)) {
873			err = -ERESTARTNOHAND;
874			goto out_unlock0;
875		}
876
877	}
878
879	ipc_update_pid(&msq->q_lspid, task_tgid(current));
880	msq->q_stime = ktime_get_real_seconds();
881
882	if (!pipelined_send(msq, msg, &wake_q)) {
883		/* no one is waiting for this message, enqueue it */
884		list_add_tail(&msg->m_list, &msq->q_messages);
885		msq->q_cbytes += msgsz;
886		msq->q_qnum++;
887		atomic_add(msgsz, &ns->msg_bytes);
888		atomic_inc(&ns->msg_hdrs);
889	}
890
891	err = 0;
892	msg = NULL;
893
894out_unlock0:
895	ipc_unlock_object(&msq->q_perm);
896	wake_up_q(&wake_q);
897out_unlock1:
898	rcu_read_unlock();
899	if (msg != NULL)
900		free_msg(msg);
901	return err;
902}
903
904long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
905		 int msgflg)
906{
907	long mtype;
908
909	if (get_user(mtype, &msgp->mtype))
910		return -EFAULT;
911	return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
912}
913
914SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
915		int, msgflg)
916{
917	return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
918}
919
920#ifdef CONFIG_COMPAT
921
922struct compat_msgbuf {
923	compat_long_t mtype;
924	char mtext[1];
925};
926
927long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
928		       compat_ssize_t msgsz, int msgflg)
929{
930	struct compat_msgbuf __user *up = compat_ptr(msgp);
931	compat_long_t mtype;
932
933	if (get_user(mtype, &up->mtype))
934		return -EFAULT;
935	return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
936}
937
938COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
939		       compat_ssize_t, msgsz, int, msgflg)
940{
941	return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
942}
943#endif
944
945static inline int convert_mode(long *msgtyp, int msgflg)
946{
947	if (msgflg & MSG_COPY)
948		return SEARCH_NUMBER;
949	/*
950	 *  find message of correct type.
951	 *  msgtyp = 0 => get first.
952	 *  msgtyp > 0 => get first message of matching type.
953	 *  msgtyp < 0 => get message with least type must be < abs(msgtype).
954	 */
955	if (*msgtyp == 0)
956		return SEARCH_ANY;
957	if (*msgtyp < 0) {
958		if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
959			*msgtyp = LONG_MAX;
960		else
961			*msgtyp = -*msgtyp;
962		return SEARCH_LESSEQUAL;
963	}
964	if (msgflg & MSG_EXCEPT)
965		return SEARCH_NOTEQUAL;
966	return SEARCH_EQUAL;
967}
968
969static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
970{
971	struct msgbuf __user *msgp = dest;
972	size_t msgsz;
973
974	if (put_user(msg->m_type, &msgp->mtype))
975		return -EFAULT;
976
977	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
978	if (store_msg(msgp->mtext, msg, msgsz))
979		return -EFAULT;
980	return msgsz;
981}
982
983#ifdef CONFIG_CHECKPOINT_RESTORE
984/*
985 * This function creates new kernel message structure, large enough to store
986 * bufsz message bytes.
987 */
988static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
989{
990	struct msg_msg *copy;
991
992	/*
993	 * Create dummy message to copy real message to.
994	 */
995	copy = load_msg(buf, bufsz);
996	if (!IS_ERR(copy))
997		copy->m_ts = bufsz;
998	return copy;
999}
1000
1001static inline void free_copy(struct msg_msg *copy)
1002{
1003	if (copy)
1004		free_msg(copy);
1005}
1006#else
1007static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1008{
1009	return ERR_PTR(-ENOSYS);
1010}
1011
1012static inline void free_copy(struct msg_msg *copy)
1013{
1014}
1015#endif
1016
1017static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
1018{
1019	struct msg_msg *msg, *found = NULL;
1020	long count = 0;
1021
1022	list_for_each_entry(msg, &msq->q_messages, m_list) {
1023		if (testmsg(msg, *msgtyp, mode) &&
1024		    !security_msg_queue_msgrcv(&msq->q_perm, msg, current,
1025					       *msgtyp, mode)) {
1026			if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
1027				*msgtyp = msg->m_type - 1;
1028				found = msg;
1029			} else if (mode == SEARCH_NUMBER) {
1030				if (*msgtyp == count)
1031					return msg;
1032			} else
1033				return msg;
1034			count++;
1035		}
1036	}
1037
1038	return found ?: ERR_PTR(-EAGAIN);
1039}
1040
1041static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
1042	       long (*msg_handler)(void __user *, struct msg_msg *, size_t))
1043{
1044	int mode;
1045	struct msg_queue *msq;
1046	struct ipc_namespace *ns;
1047	struct msg_msg *msg, *copy = NULL;
1048	DEFINE_WAKE_Q(wake_q);
1049
1050	ns = current->nsproxy->ipc_ns;
1051
1052	if (msqid < 0 || (long) bufsz < 0)
1053		return -EINVAL;
1054
1055	if (msgflg & MSG_COPY) {
1056		if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
1057			return -EINVAL;
1058		copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
1059		if (IS_ERR(copy))
1060			return PTR_ERR(copy);
1061	}
1062	mode = convert_mode(&msgtyp, msgflg);
1063
1064	rcu_read_lock();
1065	msq = msq_obtain_object_check(ns, msqid);
1066	if (IS_ERR(msq)) {
1067		rcu_read_unlock();
1068		free_copy(copy);
1069		return PTR_ERR(msq);
1070	}
1071
1072	for (;;) {
1073		struct msg_receiver msr_d;
1074
1075		msg = ERR_PTR(-EACCES);
1076		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1077			goto out_unlock1;
1078
1079		ipc_lock_object(&msq->q_perm);
1080
1081		/* raced with RMID? */
1082		if (!ipc_valid_object(&msq->q_perm)) {
1083			msg = ERR_PTR(-EIDRM);
1084			goto out_unlock0;
1085		}
1086
1087		msg = find_msg(msq, &msgtyp, mode);
1088		if (!IS_ERR(msg)) {
1089			/*
1090			 * Found a suitable message.
1091			 * Unlink it from the queue.
1092			 */
1093			if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1094				msg = ERR_PTR(-E2BIG);
1095				goto out_unlock0;
1096			}
1097			/*
1098			 * If we are copying, then do not unlink message and do
1099			 * not update queue parameters.
1100			 */
1101			if (msgflg & MSG_COPY) {
1102				msg = copy_msg(msg, copy);
1103				goto out_unlock0;
1104			}
1105
1106			list_del(&msg->m_list);
1107			msq->q_qnum--;
1108			msq->q_rtime = ktime_get_real_seconds();
1109			ipc_update_pid(&msq->q_lrpid, task_tgid(current));
1110			msq->q_cbytes -= msg->m_ts;
1111			atomic_sub(msg->m_ts, &ns->msg_bytes);
1112			atomic_dec(&ns->msg_hdrs);
1113			ss_wakeup(msq, &wake_q, false);
1114
1115			goto out_unlock0;
1116		}
1117
1118		/* No message waiting. Wait for a message */
1119		if (msgflg & IPC_NOWAIT) {
1120			msg = ERR_PTR(-ENOMSG);
1121			goto out_unlock0;
1122		}
1123
1124		list_add_tail(&msr_d.r_list, &msq->q_receivers);
1125		msr_d.r_tsk = current;
1126		msr_d.r_msgtype = msgtyp;
1127		msr_d.r_mode = mode;
1128		if (msgflg & MSG_NOERROR)
1129			msr_d.r_maxsize = INT_MAX;
1130		else
1131			msr_d.r_maxsize = bufsz;
1132		msr_d.r_msg = ERR_PTR(-EAGAIN);
1133		__set_current_state(TASK_INTERRUPTIBLE);
1134
1135		ipc_unlock_object(&msq->q_perm);
1136		rcu_read_unlock();
1137		schedule();
1138
1139		/*
1140		 * Lockless receive, part 1:
1141		 * We don't hold a reference to the queue and getting a
1142		 * reference would defeat the idea of a lockless operation,
1143		 * thus the code relies on rcu to guarantee the existence of
1144		 * msq:
1145		 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1146		 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1147		 */
1148		rcu_read_lock();
1149
1150		/*
1151		 * Lockless receive, part 2:
1152		 * The work in pipelined_send() and expunge_all():
1153		 * - Set pointer to message
1154		 * - Queue the receiver task for later wakeup
1155		 * - Wake up the process after the lock is dropped.
1156		 *
1157		 * Should the process wake up before this wakeup (due to a
1158		 * signal) it will either see the message and continue ...
1159		 */
1160		msg = READ_ONCE(msr_d.r_msg);
1161		if (msg != ERR_PTR(-EAGAIN))
1162			goto out_unlock1;
1163
1164		 /*
1165		  * ... or see -EAGAIN, acquire the lock to check the message
1166		  * again.
1167		  */
1168		ipc_lock_object(&msq->q_perm);
1169
1170		msg = msr_d.r_msg;
1171		if (msg != ERR_PTR(-EAGAIN))
1172			goto out_unlock0;
1173
1174		list_del(&msr_d.r_list);
1175		if (signal_pending(current)) {
1176			msg = ERR_PTR(-ERESTARTNOHAND);
1177			goto out_unlock0;
1178		}
1179
1180		ipc_unlock_object(&msq->q_perm);
1181	}
1182
1183out_unlock0:
1184	ipc_unlock_object(&msq->q_perm);
1185	wake_up_q(&wake_q);
1186out_unlock1:
1187	rcu_read_unlock();
1188	if (IS_ERR(msg)) {
1189		free_copy(copy);
1190		return PTR_ERR(msg);
1191	}
1192
1193	bufsz = msg_handler(buf, msg, bufsz);
1194	free_msg(msg);
1195
1196	return bufsz;
1197}
1198
1199long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
1200		 long msgtyp, int msgflg)
1201{
1202	return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1203}
1204
1205SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1206		long, msgtyp, int, msgflg)
1207{
1208	return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1209}
1210
1211#ifdef CONFIG_COMPAT
1212static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1213{
1214	struct compat_msgbuf __user *msgp = dest;
1215	size_t msgsz;
1216
1217	if (put_user(msg->m_type, &msgp->mtype))
1218		return -EFAULT;
1219
1220	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1221	if (store_msg(msgp->mtext, msg, msgsz))
1222		return -EFAULT;
1223	return msgsz;
1224}
1225
1226long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
1227			compat_long_t msgtyp, int msgflg)
1228{
1229	return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1230			 msgflg, compat_do_msg_fill);
1231}
1232
1233COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1234		       compat_ssize_t, msgsz, compat_long_t, msgtyp,
1235		       int, msgflg)
1236{
1237	return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1238}
1239#endif
1240
1241int msg_init_ns(struct ipc_namespace *ns)
1242{
1243	ns->msg_ctlmax = MSGMAX;
1244	ns->msg_ctlmnb = MSGMNB;
1245	ns->msg_ctlmni = MSGMNI;
1246
1247	atomic_set(&ns->msg_bytes, 0);
1248	atomic_set(&ns->msg_hdrs, 0);
1249	return ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1250}
1251
1252#ifdef CONFIG_IPC_NS
1253void msg_exit_ns(struct ipc_namespace *ns)
1254{
1255	free_ipcs(ns, &msg_ids(ns), freeque);
1256	idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1257	rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1258}
1259#endif
1260
1261#ifdef CONFIG_PROC_FS
1262static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1263{
1264	struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1265	struct user_namespace *user_ns = seq_user_ns(s);
1266	struct kern_ipc_perm *ipcp = it;
1267	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1268
1269	seq_printf(s,
1270		   "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1271		   msq->q_perm.key,
1272		   msq->q_perm.id,
1273		   msq->q_perm.mode,
1274		   msq->q_cbytes,
1275		   msq->q_qnum,
1276		   pid_nr_ns(msq->q_lspid, pid_ns),
1277		   pid_nr_ns(msq->q_lrpid, pid_ns),
1278		   from_kuid_munged(user_ns, msq->q_perm.uid),
1279		   from_kgid_munged(user_ns, msq->q_perm.gid),
1280		   from_kuid_munged(user_ns, msq->q_perm.cuid),
1281		   from_kgid_munged(user_ns, msq->q_perm.cgid),
1282		   msq->q_stime,
1283		   msq->q_rtime,
1284		   msq->q_ctime);
1285
1286	return 0;
1287}
1288#endif
1289
1290int __init msg_init(void)
1291{
1292	const int err = msg_init_ns(&init_ipc_ns);
1293
1294	ipc_init_proc_interface("sysvipc/msg",
1295				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1296				IPC_MSG_IDS, sysvipc_msg_proc_show);
1297	return err;
1298}
1299