xref: /linux/ipc/msg.c (revision 4b78e201)
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 */
48 struct 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 */
75 struct 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 */
87 struct 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 
msq_obtain_object(struct ipc_namespace * ns,int id)101 static 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 
msq_obtain_object_check(struct ipc_namespace * ns,int id)111 static 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 
msg_rmid(struct ipc_namespace * ns,struct msg_queue * s)122 static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
123 {
124 	ipc_rmid(&msg_ids(ns), &s->q_perm);
125 }
126 
msg_rcu_free(struct rcu_head * head)127 static 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 	kvfree(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  */
newque(struct ipc_namespace * ns,struct ipc_params * params)143 static 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 = kvmalloc(sizeof(*msq), GFP_KERNEL);
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 		kvfree(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 
msg_fits_inqueue(struct msg_queue * msq,size_t msgsz)186 static 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 
ss_add(struct msg_queue * msq,struct msg_sender * mss,size_t msgsz)192 static 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 
ss_del(struct msg_sender * mss)205 static inline void ss_del(struct msg_sender *mss)
206 {
207 	if (mss->list.next)
208 		list_del(&mss->list);
209 }
210 
ss_wakeup(struct msg_queue * msq,struct wake_q_head * wake_q,bool kill)211 static 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 
expunge_all(struct msg_queue * msq,int res,struct wake_q_head * wake_q)248 static 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 		get_task_struct(msr->r_tsk);
255 
256 		/* see MSG_BARRIER for purpose/pairing */
257 		smp_store_release(&msr->r_msg, ERR_PTR(res));
258 		wake_q_add_safe(wake_q, msr->r_tsk);
259 	}
260 }
261 
262 /*
263  * freeque() wakes up waiters on the sender and receiver waiting queue,
264  * removes the message queue from message queue ID IDR, and cleans up all the
265  * messages associated with this queue.
266  *
267  * msg_ids.rwsem (writer) and the spinlock for this message queue are held
268  * before freeque() is called. msg_ids.rwsem remains locked on exit.
269  */
freeque(struct ipc_namespace * ns,struct kern_ipc_perm * ipcp)270 static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
271 	__releases(RCU)
272 	__releases(&msq->q_perm)
273 {
274 	struct msg_msg *msg, *t;
275 	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
276 	DEFINE_WAKE_Q(wake_q);
277 
278 	expunge_all(msq, -EIDRM, &wake_q);
279 	ss_wakeup(msq, &wake_q, true);
280 	msg_rmid(ns, msq);
281 	ipc_unlock_object(&msq->q_perm);
282 	wake_up_q(&wake_q);
283 	rcu_read_unlock();
284 
285 	list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
286 		atomic_dec(&ns->msg_hdrs);
287 		free_msg(msg);
288 	}
289 	atomic_sub(msq->q_cbytes, &ns->msg_bytes);
290 	ipc_update_pid(&msq->q_lspid, NULL);
291 	ipc_update_pid(&msq->q_lrpid, NULL);
292 	ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
293 }
294 
ksys_msgget(key_t key,int msgflg)295 long ksys_msgget(key_t key, int msgflg)
296 {
297 	struct ipc_namespace *ns;
298 	static const struct ipc_ops msg_ops = {
299 		.getnew = newque,
300 		.associate = security_msg_queue_associate,
301 	};
302 	struct ipc_params msg_params;
303 
304 	ns = current->nsproxy->ipc_ns;
305 
306 	msg_params.key = key;
307 	msg_params.flg = msgflg;
308 
309 	return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
310 }
311 
SYSCALL_DEFINE2(msgget,key_t,key,int,msgflg)312 SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
313 {
314 	return ksys_msgget(key, msgflg);
315 }
316 
317 static inline unsigned long
copy_msqid_to_user(void __user * buf,struct msqid64_ds * in,int version)318 copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
319 {
320 	switch (version) {
321 	case IPC_64:
322 		return copy_to_user(buf, in, sizeof(*in));
323 	case IPC_OLD:
324 	{
325 		struct msqid_ds out;
326 
327 		memset(&out, 0, sizeof(out));
328 
329 		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
330 
331 		out.msg_stime		= in->msg_stime;
332 		out.msg_rtime		= in->msg_rtime;
333 		out.msg_ctime		= in->msg_ctime;
334 
335 		if (in->msg_cbytes > USHRT_MAX)
336 			out.msg_cbytes	= USHRT_MAX;
337 		else
338 			out.msg_cbytes	= in->msg_cbytes;
339 		out.msg_lcbytes		= in->msg_cbytes;
340 
341 		if (in->msg_qnum > USHRT_MAX)
342 			out.msg_qnum	= USHRT_MAX;
343 		else
344 			out.msg_qnum	= in->msg_qnum;
345 
346 		if (in->msg_qbytes > USHRT_MAX)
347 			out.msg_qbytes	= USHRT_MAX;
348 		else
349 			out.msg_qbytes	= in->msg_qbytes;
350 		out.msg_lqbytes		= in->msg_qbytes;
351 
352 		out.msg_lspid		= in->msg_lspid;
353 		out.msg_lrpid		= in->msg_lrpid;
354 
355 		return copy_to_user(buf, &out, sizeof(out));
356 	}
357 	default:
358 		return -EINVAL;
359 	}
360 }
361 
362 static inline unsigned long
copy_msqid_from_user(struct msqid64_ds * out,void __user * buf,int version)363 copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
364 {
365 	switch (version) {
366 	case IPC_64:
367 		if (copy_from_user(out, buf, sizeof(*out)))
368 			return -EFAULT;
369 		return 0;
370 	case IPC_OLD:
371 	{
372 		struct msqid_ds tbuf_old;
373 
374 		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
375 			return -EFAULT;
376 
377 		out->msg_perm.uid	= tbuf_old.msg_perm.uid;
378 		out->msg_perm.gid	= tbuf_old.msg_perm.gid;
379 		out->msg_perm.mode	= tbuf_old.msg_perm.mode;
380 
381 		if (tbuf_old.msg_qbytes == 0)
382 			out->msg_qbytes	= tbuf_old.msg_lqbytes;
383 		else
384 			out->msg_qbytes	= tbuf_old.msg_qbytes;
385 
386 		return 0;
387 	}
388 	default:
389 		return -EINVAL;
390 	}
391 }
392 
393 /*
394  * This function handles some msgctl commands which require the rwsem
395  * to be held in write mode.
396  * NOTE: no locks must be held, the rwsem is taken inside this function.
397  */
msgctl_down(struct ipc_namespace * ns,int msqid,int cmd,struct ipc64_perm * perm,int msg_qbytes)398 static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
399 			struct ipc64_perm *perm, int msg_qbytes)
400 {
401 	struct kern_ipc_perm *ipcp;
402 	struct msg_queue *msq;
403 	int err;
404 
405 	down_write(&msg_ids(ns).rwsem);
406 	rcu_read_lock();
407 
408 	ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd,
409 				      perm, msg_qbytes);
410 	if (IS_ERR(ipcp)) {
411 		err = PTR_ERR(ipcp);
412 		goto out_unlock1;
413 	}
414 
415 	msq = container_of(ipcp, struct msg_queue, q_perm);
416 
417 	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
418 	if (err)
419 		goto out_unlock1;
420 
421 	switch (cmd) {
422 	case IPC_RMID:
423 		ipc_lock_object(&msq->q_perm);
424 		/* freeque unlocks the ipc object and rcu */
425 		freeque(ns, ipcp);
426 		goto out_up;
427 	case IPC_SET:
428 	{
429 		DEFINE_WAKE_Q(wake_q);
430 
431 		if (msg_qbytes > ns->msg_ctlmnb &&
432 		    !capable(CAP_SYS_RESOURCE)) {
433 			err = -EPERM;
434 			goto out_unlock1;
435 		}
436 
437 		ipc_lock_object(&msq->q_perm);
438 		err = ipc_update_perm(perm, ipcp);
439 		if (err)
440 			goto out_unlock0;
441 
442 		msq->q_qbytes = msg_qbytes;
443 
444 		msq->q_ctime = ktime_get_real_seconds();
445 		/*
446 		 * Sleeping receivers might be excluded by
447 		 * stricter permissions.
448 		 */
449 		expunge_all(msq, -EAGAIN, &wake_q);
450 		/*
451 		 * Sleeping senders might be able to send
452 		 * due to a larger queue size.
453 		 */
454 		ss_wakeup(msq, &wake_q, false);
455 		ipc_unlock_object(&msq->q_perm);
456 		wake_up_q(&wake_q);
457 
458 		goto out_unlock1;
459 	}
460 	default:
461 		err = -EINVAL;
462 		goto out_unlock1;
463 	}
464 
465 out_unlock0:
466 	ipc_unlock_object(&msq->q_perm);
467 out_unlock1:
468 	rcu_read_unlock();
469 out_up:
470 	up_write(&msg_ids(ns).rwsem);
471 	return err;
472 }
473 
msgctl_info(struct ipc_namespace * ns,int msqid,int cmd,struct msginfo * msginfo)474 static int msgctl_info(struct ipc_namespace *ns, int msqid,
475 			 int cmd, struct msginfo *msginfo)
476 {
477 	int err;
478 	int max_idx;
479 
480 	/*
481 	 * We must not return kernel stack data.
482 	 * due to padding, it's not enough
483 	 * to set all member fields.
484 	 */
485 	err = security_msg_queue_msgctl(NULL, cmd);
486 	if (err)
487 		return err;
488 
489 	memset(msginfo, 0, sizeof(*msginfo));
490 	msginfo->msgmni = ns->msg_ctlmni;
491 	msginfo->msgmax = ns->msg_ctlmax;
492 	msginfo->msgmnb = ns->msg_ctlmnb;
493 	msginfo->msgssz = MSGSSZ;
494 	msginfo->msgseg = MSGSEG;
495 	down_read(&msg_ids(ns).rwsem);
496 	if (cmd == MSG_INFO) {
497 		msginfo->msgpool = msg_ids(ns).in_use;
498 		msginfo->msgmap = atomic_read(&ns->msg_hdrs);
499 		msginfo->msgtql = atomic_read(&ns->msg_bytes);
500 	} else {
501 		msginfo->msgmap = MSGMAP;
502 		msginfo->msgpool = MSGPOOL;
503 		msginfo->msgtql = MSGTQL;
504 	}
505 	max_idx = ipc_get_maxidx(&msg_ids(ns));
506 	up_read(&msg_ids(ns).rwsem);
507 	return (max_idx < 0) ? 0 : max_idx;
508 }
509 
msgctl_stat(struct ipc_namespace * ns,int msqid,int cmd,struct msqid64_ds * p)510 static int msgctl_stat(struct ipc_namespace *ns, int msqid,
511 			 int cmd, struct msqid64_ds *p)
512 {
513 	struct msg_queue *msq;
514 	int err;
515 
516 	memset(p, 0, sizeof(*p));
517 
518 	rcu_read_lock();
519 	if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
520 		msq = msq_obtain_object(ns, msqid);
521 		if (IS_ERR(msq)) {
522 			err = PTR_ERR(msq);
523 			goto out_unlock;
524 		}
525 	} else { /* IPC_STAT */
526 		msq = msq_obtain_object_check(ns, msqid);
527 		if (IS_ERR(msq)) {
528 			err = PTR_ERR(msq);
529 			goto out_unlock;
530 		}
531 	}
532 
533 	/* see comment for SHM_STAT_ANY */
534 	if (cmd == MSG_STAT_ANY)
535 		audit_ipc_obj(&msq->q_perm);
536 	else {
537 		err = -EACCES;
538 		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
539 			goto out_unlock;
540 	}
541 
542 	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
543 	if (err)
544 		goto out_unlock;
545 
546 	ipc_lock_object(&msq->q_perm);
547 
548 	if (!ipc_valid_object(&msq->q_perm)) {
549 		ipc_unlock_object(&msq->q_perm);
550 		err = -EIDRM;
551 		goto out_unlock;
552 	}
553 
554 	kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
555 	p->msg_stime  = msq->q_stime;
556 	p->msg_rtime  = msq->q_rtime;
557 	p->msg_ctime  = msq->q_ctime;
558 #ifndef CONFIG_64BIT
559 	p->msg_stime_high = msq->q_stime >> 32;
560 	p->msg_rtime_high = msq->q_rtime >> 32;
561 	p->msg_ctime_high = msq->q_ctime >> 32;
562 #endif
563 	p->msg_cbytes = msq->q_cbytes;
564 	p->msg_qnum   = msq->q_qnum;
565 	p->msg_qbytes = msq->q_qbytes;
566 	p->msg_lspid  = pid_vnr(msq->q_lspid);
567 	p->msg_lrpid  = pid_vnr(msq->q_lrpid);
568 
569 	if (cmd == IPC_STAT) {
570 		/*
571 		 * As defined in SUS:
572 		 * Return 0 on success
573 		 */
574 		err = 0;
575 	} else {
576 		/*
577 		 * MSG_STAT and MSG_STAT_ANY (both Linux specific)
578 		 * Return the full id, including the sequence number
579 		 */
580 		err = msq->q_perm.id;
581 	}
582 
583 	ipc_unlock_object(&msq->q_perm);
584 out_unlock:
585 	rcu_read_unlock();
586 	return err;
587 }
588 
ksys_msgctl(int msqid,int cmd,struct msqid_ds __user * buf,int version)589 static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version)
590 {
591 	struct ipc_namespace *ns;
592 	struct msqid64_ds msqid64;
593 	int err;
594 
595 	if (msqid < 0 || cmd < 0)
596 		return -EINVAL;
597 
598 	ns = current->nsproxy->ipc_ns;
599 
600 	switch (cmd) {
601 	case IPC_INFO:
602 	case MSG_INFO: {
603 		struct msginfo msginfo;
604 		err = msgctl_info(ns, msqid, cmd, &msginfo);
605 		if (err < 0)
606 			return err;
607 		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
608 			err = -EFAULT;
609 		return err;
610 	}
611 	case MSG_STAT:	/* msqid is an index rather than a msg queue id */
612 	case MSG_STAT_ANY:
613 	case IPC_STAT:
614 		err = msgctl_stat(ns, msqid, cmd, &msqid64);
615 		if (err < 0)
616 			return err;
617 		if (copy_msqid_to_user(buf, &msqid64, version))
618 			err = -EFAULT;
619 		return err;
620 	case IPC_SET:
621 		if (copy_msqid_from_user(&msqid64, buf, version))
622 			return -EFAULT;
623 		return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm,
624 				   msqid64.msg_qbytes);
625 	case IPC_RMID:
626 		return msgctl_down(ns, msqid, cmd, NULL, 0);
627 	default:
628 		return  -EINVAL;
629 	}
630 }
631 
SYSCALL_DEFINE3(msgctl,int,msqid,int,cmd,struct msqid_ds __user *,buf)632 SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
633 {
634 	return ksys_msgctl(msqid, cmd, buf, IPC_64);
635 }
636 
637 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
ksys_old_msgctl(int msqid,int cmd,struct msqid_ds __user * buf)638 long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
639 {
640 	int version = ipc_parse_version(&cmd);
641 
642 	return ksys_msgctl(msqid, cmd, buf, version);
643 }
644 
SYSCALL_DEFINE3(old_msgctl,int,msqid,int,cmd,struct msqid_ds __user *,buf)645 SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
646 {
647 	return ksys_old_msgctl(msqid, cmd, buf);
648 }
649 #endif
650 
651 #ifdef CONFIG_COMPAT
652 
653 struct compat_msqid_ds {
654 	struct compat_ipc_perm msg_perm;
655 	compat_uptr_t msg_first;
656 	compat_uptr_t msg_last;
657 	old_time32_t msg_stime;
658 	old_time32_t msg_rtime;
659 	old_time32_t msg_ctime;
660 	compat_ulong_t msg_lcbytes;
661 	compat_ulong_t msg_lqbytes;
662 	unsigned short msg_cbytes;
663 	unsigned short msg_qnum;
664 	unsigned short msg_qbytes;
665 	compat_ipc_pid_t msg_lspid;
666 	compat_ipc_pid_t msg_lrpid;
667 };
668 
copy_compat_msqid_from_user(struct msqid64_ds * out,void __user * buf,int version)669 static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
670 					int version)
671 {
672 	memset(out, 0, sizeof(*out));
673 	if (version == IPC_64) {
674 		struct compat_msqid64_ds __user *p = buf;
675 		if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
676 			return -EFAULT;
677 		if (get_user(out->msg_qbytes, &p->msg_qbytes))
678 			return -EFAULT;
679 	} else {
680 		struct compat_msqid_ds __user *p = buf;
681 		if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
682 			return -EFAULT;
683 		if (get_user(out->msg_qbytes, &p->msg_qbytes))
684 			return -EFAULT;
685 	}
686 	return 0;
687 }
688 
copy_compat_msqid_to_user(void __user * buf,struct msqid64_ds * in,int version)689 static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
690 					int version)
691 {
692 	if (version == IPC_64) {
693 		struct compat_msqid64_ds v;
694 		memset(&v, 0, sizeof(v));
695 		to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
696 		v.msg_stime	 = lower_32_bits(in->msg_stime);
697 		v.msg_stime_high = upper_32_bits(in->msg_stime);
698 		v.msg_rtime	 = lower_32_bits(in->msg_rtime);
699 		v.msg_rtime_high = upper_32_bits(in->msg_rtime);
700 		v.msg_ctime	 = lower_32_bits(in->msg_ctime);
701 		v.msg_ctime_high = upper_32_bits(in->msg_ctime);
702 		v.msg_cbytes = in->msg_cbytes;
703 		v.msg_qnum = in->msg_qnum;
704 		v.msg_qbytes = in->msg_qbytes;
705 		v.msg_lspid = in->msg_lspid;
706 		v.msg_lrpid = in->msg_lrpid;
707 		return copy_to_user(buf, &v, sizeof(v));
708 	} else {
709 		struct compat_msqid_ds v;
710 		memset(&v, 0, sizeof(v));
711 		to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
712 		v.msg_stime = in->msg_stime;
713 		v.msg_rtime = in->msg_rtime;
714 		v.msg_ctime = in->msg_ctime;
715 		v.msg_cbytes = in->msg_cbytes;
716 		v.msg_qnum = in->msg_qnum;
717 		v.msg_qbytes = in->msg_qbytes;
718 		v.msg_lspid = in->msg_lspid;
719 		v.msg_lrpid = in->msg_lrpid;
720 		return copy_to_user(buf, &v, sizeof(v));
721 	}
722 }
723 
compat_ksys_msgctl(int msqid,int cmd,void __user * uptr,int version)724 static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version)
725 {
726 	struct ipc_namespace *ns;
727 	int err;
728 	struct msqid64_ds msqid64;
729 
730 	ns = current->nsproxy->ipc_ns;
731 
732 	if (msqid < 0 || cmd < 0)
733 		return -EINVAL;
734 
735 	switch (cmd & (~IPC_64)) {
736 	case IPC_INFO:
737 	case MSG_INFO: {
738 		struct msginfo msginfo;
739 		err = msgctl_info(ns, msqid, cmd, &msginfo);
740 		if (err < 0)
741 			return err;
742 		if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
743 			err = -EFAULT;
744 		return err;
745 	}
746 	case IPC_STAT:
747 	case MSG_STAT:
748 	case MSG_STAT_ANY:
749 		err = msgctl_stat(ns, msqid, cmd, &msqid64);
750 		if (err < 0)
751 			return err;
752 		if (copy_compat_msqid_to_user(uptr, &msqid64, version))
753 			err = -EFAULT;
754 		return err;
755 	case IPC_SET:
756 		if (copy_compat_msqid_from_user(&msqid64, uptr, version))
757 			return -EFAULT;
758 		return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes);
759 	case IPC_RMID:
760 		return msgctl_down(ns, msqid, cmd, NULL, 0);
761 	default:
762 		return -EINVAL;
763 	}
764 }
765 
COMPAT_SYSCALL_DEFINE3(msgctl,int,msqid,int,cmd,void __user *,uptr)766 COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
767 {
768 	return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64);
769 }
770 
771 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
compat_ksys_old_msgctl(int msqid,int cmd,void __user * uptr)772 long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr)
773 {
774 	int version = compat_ipc_parse_version(&cmd);
775 
776 	return compat_ksys_msgctl(msqid, cmd, uptr, version);
777 }
778 
COMPAT_SYSCALL_DEFINE3(old_msgctl,int,msqid,int,cmd,void __user *,uptr)779 COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr)
780 {
781 	return compat_ksys_old_msgctl(msqid, cmd, uptr);
782 }
783 #endif
784 #endif
785 
testmsg(struct msg_msg * msg,long type,int mode)786 static int testmsg(struct msg_msg *msg, long type, int mode)
787 {
788 	switch (mode) {
789 	case SEARCH_ANY:
790 	case SEARCH_NUMBER:
791 		return 1;
792 	case SEARCH_LESSEQUAL:
793 		if (msg->m_type <= type)
794 			return 1;
795 		break;
796 	case SEARCH_EQUAL:
797 		if (msg->m_type == type)
798 			return 1;
799 		break;
800 	case SEARCH_NOTEQUAL:
801 		if (msg->m_type != type)
802 			return 1;
803 		break;
804 	}
805 	return 0;
806 }
807 
pipelined_send(struct msg_queue * msq,struct msg_msg * msg,struct wake_q_head * wake_q)808 static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
809 				 struct wake_q_head *wake_q)
810 {
811 	struct msg_receiver *msr, *t;
812 
813 	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
814 		if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
815 		    !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk,
816 					       msr->r_msgtype, msr->r_mode)) {
817 
818 			list_del(&msr->r_list);
819 			if (msr->r_maxsize < msg->m_ts) {
820 				wake_q_add(wake_q, msr->r_tsk);
821 
822 				/* See expunge_all regarding memory barrier */
823 				smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG));
824 			} else {
825 				ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
826 				msq->q_rtime = ktime_get_real_seconds();
827 
828 				wake_q_add(wake_q, msr->r_tsk);
829 
830 				/* See expunge_all regarding memory barrier */
831 				smp_store_release(&msr->r_msg, msg);
832 				return 1;
833 			}
834 		}
835 	}
836 
837 	return 0;
838 }
839 
do_msgsnd(int msqid,long mtype,void __user * mtext,size_t msgsz,int msgflg)840 static long do_msgsnd(int msqid, long mtype, void __user *mtext,
841 		size_t msgsz, int msgflg)
842 {
843 	struct msg_queue *msq;
844 	struct msg_msg *msg;
845 	int err;
846 	struct ipc_namespace *ns;
847 	DEFINE_WAKE_Q(wake_q);
848 
849 	ns = current->nsproxy->ipc_ns;
850 
851 	if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
852 		return -EINVAL;
853 	if (mtype < 1)
854 		return -EINVAL;
855 
856 	msg = load_msg(mtext, msgsz);
857 	if (IS_ERR(msg))
858 		return PTR_ERR(msg);
859 
860 	msg->m_type = mtype;
861 	msg->m_ts = msgsz;
862 
863 	rcu_read_lock();
864 	msq = msq_obtain_object_check(ns, msqid);
865 	if (IS_ERR(msq)) {
866 		err = PTR_ERR(msq);
867 		goto out_unlock1;
868 	}
869 
870 	ipc_lock_object(&msq->q_perm);
871 
872 	for (;;) {
873 		struct msg_sender s;
874 
875 		err = -EACCES;
876 		if (ipcperms(ns, &msq->q_perm, S_IWUGO))
877 			goto out_unlock0;
878 
879 		/* raced with RMID? */
880 		if (!ipc_valid_object(&msq->q_perm)) {
881 			err = -EIDRM;
882 			goto out_unlock0;
883 		}
884 
885 		err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg);
886 		if (err)
887 			goto out_unlock0;
888 
889 		if (msg_fits_inqueue(msq, msgsz))
890 			break;
891 
892 		/* queue full, wait: */
893 		if (msgflg & IPC_NOWAIT) {
894 			err = -EAGAIN;
895 			goto out_unlock0;
896 		}
897 
898 		/* enqueue the sender and prepare to block */
899 		ss_add(msq, &s, msgsz);
900 
901 		if (!ipc_rcu_getref(&msq->q_perm)) {
902 			err = -EIDRM;
903 			goto out_unlock0;
904 		}
905 
906 		ipc_unlock_object(&msq->q_perm);
907 		rcu_read_unlock();
908 		schedule();
909 
910 		rcu_read_lock();
911 		ipc_lock_object(&msq->q_perm);
912 
913 		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
914 		/* raced with RMID? */
915 		if (!ipc_valid_object(&msq->q_perm)) {
916 			err = -EIDRM;
917 			goto out_unlock0;
918 		}
919 		ss_del(&s);
920 
921 		if (signal_pending(current)) {
922 			err = -ERESTARTNOHAND;
923 			goto out_unlock0;
924 		}
925 
926 	}
927 
928 	ipc_update_pid(&msq->q_lspid, task_tgid(current));
929 	msq->q_stime = ktime_get_real_seconds();
930 
931 	if (!pipelined_send(msq, msg, &wake_q)) {
932 		/* no one is waiting for this message, enqueue it */
933 		list_add_tail(&msg->m_list, &msq->q_messages);
934 		msq->q_cbytes += msgsz;
935 		msq->q_qnum++;
936 		atomic_add(msgsz, &ns->msg_bytes);
937 		atomic_inc(&ns->msg_hdrs);
938 	}
939 
940 	err = 0;
941 	msg = NULL;
942 
943 out_unlock0:
944 	ipc_unlock_object(&msq->q_perm);
945 	wake_up_q(&wake_q);
946 out_unlock1:
947 	rcu_read_unlock();
948 	if (msg != NULL)
949 		free_msg(msg);
950 	return err;
951 }
952 
ksys_msgsnd(int msqid,struct msgbuf __user * msgp,size_t msgsz,int msgflg)953 long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
954 		 int msgflg)
955 {
956 	long mtype;
957 
958 	if (get_user(mtype, &msgp->mtype))
959 		return -EFAULT;
960 	return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
961 }
962 
SYSCALL_DEFINE4(msgsnd,int,msqid,struct msgbuf __user *,msgp,size_t,msgsz,int,msgflg)963 SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
964 		int, msgflg)
965 {
966 	return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
967 }
968 
969 #ifdef CONFIG_COMPAT
970 
971 struct compat_msgbuf {
972 	compat_long_t mtype;
973 	char mtext[1];
974 };
975 
compat_ksys_msgsnd(int msqid,compat_uptr_t msgp,compat_ssize_t msgsz,int msgflg)976 long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
977 		       compat_ssize_t msgsz, int msgflg)
978 {
979 	struct compat_msgbuf __user *up = compat_ptr(msgp);
980 	compat_long_t mtype;
981 
982 	if (get_user(mtype, &up->mtype))
983 		return -EFAULT;
984 	return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
985 }
986 
COMPAT_SYSCALL_DEFINE4(msgsnd,int,msqid,compat_uptr_t,msgp,compat_ssize_t,msgsz,int,msgflg)987 COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
988 		       compat_ssize_t, msgsz, int, msgflg)
989 {
990 	return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
991 }
992 #endif
993 
convert_mode(long * msgtyp,int msgflg)994 static inline int convert_mode(long *msgtyp, int msgflg)
995 {
996 	if (msgflg & MSG_COPY)
997 		return SEARCH_NUMBER;
998 	/*
999 	 *  find message of correct type.
1000 	 *  msgtyp = 0 => get first.
1001 	 *  msgtyp > 0 => get first message of matching type.
1002 	 *  msgtyp < 0 => get message with least type must be < abs(msgtype).
1003 	 */
1004 	if (*msgtyp == 0)
1005 		return SEARCH_ANY;
1006 	if (*msgtyp < 0) {
1007 		if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
1008 			*msgtyp = LONG_MAX;
1009 		else
1010 			*msgtyp = -*msgtyp;
1011 		return SEARCH_LESSEQUAL;
1012 	}
1013 	if (msgflg & MSG_EXCEPT)
1014 		return SEARCH_NOTEQUAL;
1015 	return SEARCH_EQUAL;
1016 }
1017 
do_msg_fill(void __user * dest,struct msg_msg * msg,size_t bufsz)1018 static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1019 {
1020 	struct msgbuf __user *msgp = dest;
1021 	size_t msgsz;
1022 
1023 	if (put_user(msg->m_type, &msgp->mtype))
1024 		return -EFAULT;
1025 
1026 	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1027 	if (store_msg(msgp->mtext, msg, msgsz))
1028 		return -EFAULT;
1029 	return msgsz;
1030 }
1031 
1032 #ifdef CONFIG_CHECKPOINT_RESTORE
1033 /*
1034  * This function creates new kernel message structure, large enough to store
1035  * bufsz message bytes.
1036  */
prepare_copy(void __user * buf,size_t bufsz)1037 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1038 {
1039 	struct msg_msg *copy;
1040 
1041 	/*
1042 	 * Create dummy message to copy real message to.
1043 	 */
1044 	copy = load_msg(buf, bufsz);
1045 	if (!IS_ERR(copy))
1046 		copy->m_ts = bufsz;
1047 	return copy;
1048 }
1049 
free_copy(struct msg_msg * copy)1050 static inline void free_copy(struct msg_msg *copy)
1051 {
1052 	if (copy)
1053 		free_msg(copy);
1054 }
1055 #else
prepare_copy(void __user * buf,size_t bufsz)1056 static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1057 {
1058 	return ERR_PTR(-ENOSYS);
1059 }
1060 
free_copy(struct msg_msg * copy)1061 static inline void free_copy(struct msg_msg *copy)
1062 {
1063 }
1064 #endif
1065 
find_msg(struct msg_queue * msq,long * msgtyp,int mode)1066 static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
1067 {
1068 	struct msg_msg *msg, *found = NULL;
1069 	long count = 0;
1070 
1071 	list_for_each_entry(msg, &msq->q_messages, m_list) {
1072 		if (testmsg(msg, *msgtyp, mode) &&
1073 		    !security_msg_queue_msgrcv(&msq->q_perm, msg, current,
1074 					       *msgtyp, mode)) {
1075 			if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
1076 				*msgtyp = msg->m_type - 1;
1077 				found = msg;
1078 			} else if (mode == SEARCH_NUMBER) {
1079 				if (*msgtyp == count)
1080 					return msg;
1081 			} else
1082 				return msg;
1083 			count++;
1084 		}
1085 	}
1086 
1087 	return found ?: ERR_PTR(-EAGAIN);
1088 }
1089 
do_msgrcv(int msqid,void __user * buf,size_t bufsz,long msgtyp,int msgflg,long (* msg_handler)(void __user *,struct msg_msg *,size_t))1090 static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
1091 	       long (*msg_handler)(void __user *, struct msg_msg *, size_t))
1092 {
1093 	int mode;
1094 	struct msg_queue *msq;
1095 	struct ipc_namespace *ns;
1096 	struct msg_msg *msg, *copy = NULL;
1097 	DEFINE_WAKE_Q(wake_q);
1098 
1099 	ns = current->nsproxy->ipc_ns;
1100 
1101 	if (msqid < 0 || (long) bufsz < 0)
1102 		return -EINVAL;
1103 
1104 	if (msgflg & MSG_COPY) {
1105 		if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
1106 			return -EINVAL;
1107 		copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
1108 		if (IS_ERR(copy))
1109 			return PTR_ERR(copy);
1110 	}
1111 	mode = convert_mode(&msgtyp, msgflg);
1112 
1113 	rcu_read_lock();
1114 	msq = msq_obtain_object_check(ns, msqid);
1115 	if (IS_ERR(msq)) {
1116 		rcu_read_unlock();
1117 		free_copy(copy);
1118 		return PTR_ERR(msq);
1119 	}
1120 
1121 	for (;;) {
1122 		struct msg_receiver msr_d;
1123 
1124 		msg = ERR_PTR(-EACCES);
1125 		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1126 			goto out_unlock1;
1127 
1128 		ipc_lock_object(&msq->q_perm);
1129 
1130 		/* raced with RMID? */
1131 		if (!ipc_valid_object(&msq->q_perm)) {
1132 			msg = ERR_PTR(-EIDRM);
1133 			goto out_unlock0;
1134 		}
1135 
1136 		msg = find_msg(msq, &msgtyp, mode);
1137 		if (!IS_ERR(msg)) {
1138 			/*
1139 			 * Found a suitable message.
1140 			 * Unlink it from the queue.
1141 			 */
1142 			if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1143 				msg = ERR_PTR(-E2BIG);
1144 				goto out_unlock0;
1145 			}
1146 			/*
1147 			 * If we are copying, then do not unlink message and do
1148 			 * not update queue parameters.
1149 			 */
1150 			if (msgflg & MSG_COPY) {
1151 				msg = copy_msg(msg, copy);
1152 				goto out_unlock0;
1153 			}
1154 
1155 			list_del(&msg->m_list);
1156 			msq->q_qnum--;
1157 			msq->q_rtime = ktime_get_real_seconds();
1158 			ipc_update_pid(&msq->q_lrpid, task_tgid(current));
1159 			msq->q_cbytes -= msg->m_ts;
1160 			atomic_sub(msg->m_ts, &ns->msg_bytes);
1161 			atomic_dec(&ns->msg_hdrs);
1162 			ss_wakeup(msq, &wake_q, false);
1163 
1164 			goto out_unlock0;
1165 		}
1166 
1167 		/* No message waiting. Wait for a message */
1168 		if (msgflg & IPC_NOWAIT) {
1169 			msg = ERR_PTR(-ENOMSG);
1170 			goto out_unlock0;
1171 		}
1172 
1173 		list_add_tail(&msr_d.r_list, &msq->q_receivers);
1174 		msr_d.r_tsk = current;
1175 		msr_d.r_msgtype = msgtyp;
1176 		msr_d.r_mode = mode;
1177 		if (msgflg & MSG_NOERROR)
1178 			msr_d.r_maxsize = INT_MAX;
1179 		else
1180 			msr_d.r_maxsize = bufsz;
1181 
1182 		/* memory barrier not require due to ipc_lock_object() */
1183 		WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN));
1184 
1185 		/* memory barrier not required, we own ipc_lock_object() */
1186 		__set_current_state(TASK_INTERRUPTIBLE);
1187 
1188 		ipc_unlock_object(&msq->q_perm);
1189 		rcu_read_unlock();
1190 		schedule();
1191 
1192 		/*
1193 		 * Lockless receive, part 1:
1194 		 * We don't hold a reference to the queue and getting a
1195 		 * reference would defeat the idea of a lockless operation,
1196 		 * thus the code relies on rcu to guarantee the existence of
1197 		 * msq:
1198 		 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1199 		 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
1200 		 */
1201 		rcu_read_lock();
1202 
1203 		/*
1204 		 * Lockless receive, part 2:
1205 		 * The work in pipelined_send() and expunge_all():
1206 		 * - Set pointer to message
1207 		 * - Queue the receiver task for later wakeup
1208 		 * - Wake up the process after the lock is dropped.
1209 		 *
1210 		 * Should the process wake up before this wakeup (due to a
1211 		 * signal) it will either see the message and continue ...
1212 		 */
1213 		msg = READ_ONCE(msr_d.r_msg);
1214 		if (msg != ERR_PTR(-EAGAIN)) {
1215 			/* see MSG_BARRIER for purpose/pairing */
1216 			smp_acquire__after_ctrl_dep();
1217 
1218 			goto out_unlock1;
1219 		}
1220 
1221 		 /*
1222 		  * ... or see -EAGAIN, acquire the lock to check the message
1223 		  * again.
1224 		  */
1225 		ipc_lock_object(&msq->q_perm);
1226 
1227 		msg = READ_ONCE(msr_d.r_msg);
1228 		if (msg != ERR_PTR(-EAGAIN))
1229 			goto out_unlock0;
1230 
1231 		list_del(&msr_d.r_list);
1232 		if (signal_pending(current)) {
1233 			msg = ERR_PTR(-ERESTARTNOHAND);
1234 			goto out_unlock0;
1235 		}
1236 
1237 		ipc_unlock_object(&msq->q_perm);
1238 	}
1239 
1240 out_unlock0:
1241 	ipc_unlock_object(&msq->q_perm);
1242 	wake_up_q(&wake_q);
1243 out_unlock1:
1244 	rcu_read_unlock();
1245 	if (IS_ERR(msg)) {
1246 		free_copy(copy);
1247 		return PTR_ERR(msg);
1248 	}
1249 
1250 	bufsz = msg_handler(buf, msg, bufsz);
1251 	free_msg(msg);
1252 
1253 	return bufsz;
1254 }
1255 
ksys_msgrcv(int msqid,struct msgbuf __user * msgp,size_t msgsz,long msgtyp,int msgflg)1256 long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
1257 		 long msgtyp, int msgflg)
1258 {
1259 	return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1260 }
1261 
SYSCALL_DEFINE5(msgrcv,int,msqid,struct msgbuf __user *,msgp,size_t,msgsz,long,msgtyp,int,msgflg)1262 SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1263 		long, msgtyp, int, msgflg)
1264 {
1265 	return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1266 }
1267 
1268 #ifdef CONFIG_COMPAT
compat_do_msg_fill(void __user * dest,struct msg_msg * msg,size_t bufsz)1269 static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1270 {
1271 	struct compat_msgbuf __user *msgp = dest;
1272 	size_t msgsz;
1273 
1274 	if (put_user(msg->m_type, &msgp->mtype))
1275 		return -EFAULT;
1276 
1277 	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1278 	if (store_msg(msgp->mtext, msg, msgsz))
1279 		return -EFAULT;
1280 	return msgsz;
1281 }
1282 
compat_ksys_msgrcv(int msqid,compat_uptr_t msgp,compat_ssize_t msgsz,compat_long_t msgtyp,int msgflg)1283 long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
1284 			compat_long_t msgtyp, int msgflg)
1285 {
1286 	return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1287 			 msgflg, compat_do_msg_fill);
1288 }
1289 
COMPAT_SYSCALL_DEFINE5(msgrcv,int,msqid,compat_uptr_t,msgp,compat_ssize_t,msgsz,compat_long_t,msgtyp,int,msgflg)1290 COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1291 		       compat_ssize_t, msgsz, compat_long_t, msgtyp,
1292 		       int, msgflg)
1293 {
1294 	return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1295 }
1296 #endif
1297 
msg_init_ns(struct ipc_namespace * ns)1298 void msg_init_ns(struct ipc_namespace *ns)
1299 {
1300 	ns->msg_ctlmax = MSGMAX;
1301 	ns->msg_ctlmnb = MSGMNB;
1302 	ns->msg_ctlmni = MSGMNI;
1303 
1304 	atomic_set(&ns->msg_bytes, 0);
1305 	atomic_set(&ns->msg_hdrs, 0);
1306 	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1307 }
1308 
1309 #ifdef CONFIG_IPC_NS
msg_exit_ns(struct ipc_namespace * ns)1310 void msg_exit_ns(struct ipc_namespace *ns)
1311 {
1312 	free_ipcs(ns, &msg_ids(ns), freeque);
1313 	idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1314 	rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1315 }
1316 #endif
1317 
1318 #ifdef CONFIG_PROC_FS
sysvipc_msg_proc_show(struct seq_file * s,void * it)1319 static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1320 {
1321 	struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1322 	struct user_namespace *user_ns = seq_user_ns(s);
1323 	struct kern_ipc_perm *ipcp = it;
1324 	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1325 
1326 	seq_printf(s,
1327 		   "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1328 		   msq->q_perm.key,
1329 		   msq->q_perm.id,
1330 		   msq->q_perm.mode,
1331 		   msq->q_cbytes,
1332 		   msq->q_qnum,
1333 		   pid_nr_ns(msq->q_lspid, pid_ns),
1334 		   pid_nr_ns(msq->q_lrpid, pid_ns),
1335 		   from_kuid_munged(user_ns, msq->q_perm.uid),
1336 		   from_kgid_munged(user_ns, msq->q_perm.gid),
1337 		   from_kuid_munged(user_ns, msq->q_perm.cuid),
1338 		   from_kgid_munged(user_ns, msq->q_perm.cgid),
1339 		   msq->q_stime,
1340 		   msq->q_rtime,
1341 		   msq->q_ctime);
1342 
1343 	return 0;
1344 }
1345 #endif
1346 
msg_init(void)1347 void __init msg_init(void)
1348 {
1349 	msg_init_ns(&init_ipc_ns);
1350 
1351 	ipc_init_proc_interface("sysvipc/msg",
1352 				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1353 				IPC_MSG_IDS, sysvipc_msg_proc_show);
1354 }
1355