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v3.1
 
  1/*
  2 * linux/ipc/msg.c
  3 * Copyright (C) 1992 Krishna Balasubramanian
  4 *
  5 * Removed all the remaining kerneld mess
  6 * Catch the -EFAULT stuff properly
  7 * Use GFP_KERNEL for messages as in 1.2
  8 * Fixed up the unchecked user space derefs
  9 * Copyright (C) 1998 Alan Cox & Andi Kleen
 10 *
 11 * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
 12 *
 13 * mostly rewritten, threaded and wake-one semantics added
 14 * MSGMAX limit removed, sysctl's added
 15 * (c) 1999 Manfred Spraul <manfred@colorfullife.com>
 16 *
 17 * support for audit of ipc object properties and permission changes
 18 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
 19 *
 20 * namespaces support
 21 * OpenVZ, SWsoft Inc.
 22 * Pavel Emelianov <xemul@openvz.org>
 23 */
 24
 25#include <linux/capability.h>
 26#include <linux/msg.h>
 27#include <linux/spinlock.h>
 28#include <linux/init.h>
 29#include <linux/mm.h>
 30#include <linux/proc_fs.h>
 31#include <linux/list.h>
 32#include <linux/security.h>
 33#include <linux/sched.h>
 34#include <linux/syscalls.h>
 35#include <linux/audit.h>
 36#include <linux/seq_file.h>
 37#include <linux/rwsem.h>
 38#include <linux/nsproxy.h>
 39#include <linux/ipc_namespace.h>
 
 
 40
 41#include <asm/current.h>
 42#include <asm/uaccess.h>
 43#include "util.h"
 44
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 45/*
 46 * one msg_receiver structure for each sleeping receiver:
 
 
 
 
 
 
 47 */
 
 
 48struct msg_receiver {
 49	struct list_head	r_list;
 50	struct task_struct	*r_tsk;
 51
 52	int			r_mode;
 53	long			r_msgtype;
 54	long			r_maxsize;
 55
 56	struct msg_msg		*volatile r_msg;
 57};
 58
 59/* one msg_sender for each sleeping sender */
 60struct msg_sender {
 61	struct list_head	list;
 62	struct task_struct	*tsk;
 
 63};
 64
 65#define SEARCH_ANY		1
 66#define SEARCH_EQUAL		2
 67#define SEARCH_NOTEQUAL		3
 68#define SEARCH_LESSEQUAL	4
 
 69
 70#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
 71
 72#define msg_unlock(msq)		ipc_unlock(&(msq)->q_perm)
 73
 74static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
 75static int newque(struct ipc_namespace *, struct ipc_params *);
 76#ifdef CONFIG_PROC_FS
 77static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
 78#endif
 79
 80/*
 81 * Scale msgmni with the available lowmem size: the memory dedicated to msg
 82 * queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
 83 * Also take into account the number of nsproxies created so far.
 84 * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
 85 */
 86void recompute_msgmni(struct ipc_namespace *ns)
 87{
 88	struct sysinfo i;
 89	unsigned long allowed;
 90	int nb_ns;
 91
 92	si_meminfo(&i);
 93	allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
 94		/ MSGMNB;
 95	nb_ns = atomic_read(&nr_ipc_ns);
 96	allowed /= nb_ns;
 97
 98	if (allowed < MSGMNI) {
 99		ns->msg_ctlmni = MSGMNI;
100		return;
101	}
102
103	if (allowed > IPCMNI / nb_ns) {
104		ns->msg_ctlmni = IPCMNI / nb_ns;
105		return;
106	}
107
108	ns->msg_ctlmni = allowed;
109}
110
111void msg_init_ns(struct ipc_namespace *ns)
112{
113	ns->msg_ctlmax = MSGMAX;
114	ns->msg_ctlmnb = MSGMNB;
115
116	recompute_msgmni(ns);
117
118	atomic_set(&ns->msg_bytes, 0);
119	atomic_set(&ns->msg_hdrs, 0);
120	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
121}
122
123#ifdef CONFIG_IPC_NS
124void msg_exit_ns(struct ipc_namespace *ns)
125{
126	free_ipcs(ns, &msg_ids(ns), freeque);
127	idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
128}
129#endif
130
131void __init msg_init(void)
132{
133	msg_init_ns(&init_ipc_ns);
134
135	printk(KERN_INFO "msgmni has been set to %d\n",
136		init_ipc_ns.msg_ctlmni);
137
138	ipc_init_proc_interface("sysvipc/msg",
139				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
140				IPC_MSG_IDS, sysvipc_msg_proc_show);
141}
142
143/*
144 * msg_lock_(check_) routines are called in the paths where the rw_mutex
145 * is not held.
146 */
147static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
148{
149	struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);
150
151	if (IS_ERR(ipcp))
152		return (struct msg_queue *)ipcp;
153
154	return container_of(ipcp, struct msg_queue, q_perm);
155}
156
157static inline struct msg_queue *msg_lock_check(struct ipc_namespace *ns,
158						int id)
159{
160	struct kern_ipc_perm *ipcp = ipc_lock_check(&msg_ids(ns), id);
161
162	if (IS_ERR(ipcp))
163		return (struct msg_queue *)ipcp;
164
165	return container_of(ipcp, struct msg_queue, q_perm);
166}
167
168static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
169{
170	ipc_rmid(&msg_ids(ns), &s->q_perm);
171}
172
 
 
 
 
 
 
 
 
 
173/**
174 * newque - Create a new msg queue
175 * @ns: namespace
176 * @params: ptr to the structure that contains the key and msgflg
177 *
178 * Called with msg_ids.rw_mutex held (writer)
179 */
180static int newque(struct ipc_namespace *ns, struct ipc_params *params)
181{
182	struct msg_queue *msq;
183	int id, retval;
184	key_t key = params->key;
185	int msgflg = params->flg;
186
187	msq = ipc_rcu_alloc(sizeof(*msq));
188	if (!msq)
189		return -ENOMEM;
190
191	msq->q_perm.mode = msgflg & S_IRWXUGO;
192	msq->q_perm.key = key;
193
194	msq->q_perm.security = NULL;
195	retval = security_msg_queue_alloc(msq);
196	if (retval) {
197		ipc_rcu_putref(msq);
198		return retval;
199	}
200
201	/*
202	 * ipc_addid() locks msq
203	 */
204	id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
205	if (id < 0) {
206		security_msg_queue_free(msq);
207		ipc_rcu_putref(msq);
208		return id;
209	}
210
211	msq->q_stime = msq->q_rtime = 0;
212	msq->q_ctime = get_seconds();
213	msq->q_cbytes = msq->q_qnum = 0;
214	msq->q_qbytes = ns->msg_ctlmnb;
215	msq->q_lspid = msq->q_lrpid = 0;
216	INIT_LIST_HEAD(&msq->q_messages);
217	INIT_LIST_HEAD(&msq->q_receivers);
218	INIT_LIST_HEAD(&msq->q_senders);
219
220	msg_unlock(msq);
 
 
 
 
 
 
 
 
221
222	return msq->q_perm.id;
223}
224
225static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
 
 
 
 
 
 
 
226{
227	mss->tsk = current;
228	current->state = TASK_INTERRUPTIBLE;
 
 
 
 
 
229	list_add_tail(&mss->list, &msq->q_senders);
230}
231
232static inline void ss_del(struct msg_sender *mss)
233{
234	if (mss->list.next != NULL)
235		list_del(&mss->list);
236}
237
238static void ss_wakeup(struct list_head *h, int kill)
 
239{
240	struct list_head *tmp;
 
 
241
242	tmp = h->next;
243	while (tmp != h) {
244		struct msg_sender *mss;
245
246		mss = list_entry(tmp, struct msg_sender, list);
247		tmp = tmp->next;
248		if (kill)
249			mss->list.next = NULL;
250		wake_up_process(mss->tsk);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
251	}
252}
253
254static void expunge_all(struct msg_queue *msq, int res)
 
255{
256	struct list_head *tmp;
257
258	tmp = msq->q_receivers.next;
259	while (tmp != &msq->q_receivers) {
260		struct msg_receiver *msr;
261
262		msr = list_entry(tmp, struct msg_receiver, r_list);
263		tmp = tmp->next;
264		msr->r_msg = NULL;
265		wake_up_process(msr->r_tsk);
266		smp_mb();
267		msr->r_msg = ERR_PTR(res);
268	}
269}
270
271/*
272 * freeque() wakes up waiters on the sender and receiver waiting queue,
273 * removes the message queue from message queue ID IDR, and cleans up all the
274 * messages associated with this queue.
275 *
276 * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
277 * before freeque() is called. msg_ids.rw_mutex remains locked on exit.
278 */
279static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 
 
280{
281	struct list_head *tmp;
282	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 
283
284	expunge_all(msq, -EIDRM);
285	ss_wakeup(&msq->q_senders, 1);
286	msg_rmid(ns, msq);
287	msg_unlock(msq);
288
289	tmp = msq->q_messages.next;
290	while (tmp != &msq->q_messages) {
291		struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list);
292
293		tmp = tmp->next;
294		atomic_dec(&ns->msg_hdrs);
295		free_msg(msg);
296	}
297	atomic_sub(msq->q_cbytes, &ns->msg_bytes);
298	security_msg_queue_free(msq);
299	ipc_rcu_putref(msq);
 
300}
301
302/*
303 * Called with msg_ids.rw_mutex and ipcp locked.
304 */
305static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
306{
307	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
308
309	return security_msg_queue_associate(msq, msgflg);
310}
311
312SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
313{
314	struct ipc_namespace *ns;
315	struct ipc_ops msg_ops;
 
 
 
316	struct ipc_params msg_params;
317
318	ns = current->nsproxy->ipc_ns;
319
320	msg_ops.getnew = newque;
321	msg_ops.associate = msg_security;
322	msg_ops.more_checks = NULL;
323
324	msg_params.key = key;
325	msg_params.flg = msgflg;
326
327	return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
328}
329
 
 
 
 
 
330static inline unsigned long
331copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
332{
333	switch(version) {
334	case IPC_64:
335		return copy_to_user(buf, in, sizeof(*in));
336	case IPC_OLD:
337	{
338		struct msqid_ds out;
339
340		memset(&out, 0, sizeof(out));
341
342		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
343
344		out.msg_stime		= in->msg_stime;
345		out.msg_rtime		= in->msg_rtime;
346		out.msg_ctime		= in->msg_ctime;
347
348		if (in->msg_cbytes > USHRT_MAX)
349			out.msg_cbytes	= USHRT_MAX;
350		else
351			out.msg_cbytes	= in->msg_cbytes;
352		out.msg_lcbytes		= in->msg_cbytes;
353
354		if (in->msg_qnum > USHRT_MAX)
355			out.msg_qnum	= USHRT_MAX;
356		else
357			out.msg_qnum	= in->msg_qnum;
358
359		if (in->msg_qbytes > USHRT_MAX)
360			out.msg_qbytes	= USHRT_MAX;
361		else
362			out.msg_qbytes	= in->msg_qbytes;
363		out.msg_lqbytes		= in->msg_qbytes;
364
365		out.msg_lspid		= in->msg_lspid;
366		out.msg_lrpid		= in->msg_lrpid;
367
368		return copy_to_user(buf, &out, sizeof(out));
369	}
370	default:
371		return -EINVAL;
372	}
373}
374
375static inline unsigned long
376copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
377{
378	switch(version) {
379	case IPC_64:
380		if (copy_from_user(out, buf, sizeof(*out)))
381			return -EFAULT;
382		return 0;
383	case IPC_OLD:
384	{
385		struct msqid_ds tbuf_old;
386
387		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
388			return -EFAULT;
389
390		out->msg_perm.uid      	= tbuf_old.msg_perm.uid;
391		out->msg_perm.gid      	= tbuf_old.msg_perm.gid;
392		out->msg_perm.mode     	= tbuf_old.msg_perm.mode;
393
394		if (tbuf_old.msg_qbytes == 0)
395			out->msg_qbytes	= tbuf_old.msg_lqbytes;
396		else
397			out->msg_qbytes	= tbuf_old.msg_qbytes;
398
399		return 0;
400	}
401	default:
402		return -EINVAL;
403	}
404}
405
406/*
407 * This function handles some msgctl commands which require the rw_mutex
408 * to be held in write mode.
409 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
410 */
411static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
412		       struct msqid_ds __user *buf, int version)
413{
414	struct kern_ipc_perm *ipcp;
415	struct msqid64_ds uninitialized_var(msqid64);
416	struct msg_queue *msq;
417	int err;
418
419	if (cmd == IPC_SET) {
420		if (copy_msqid_from_user(&msqid64, buf, version))
421			return -EFAULT;
422	}
423
424	ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd,
425			       &msqid64.msg_perm, msqid64.msg_qbytes);
426	if (IS_ERR(ipcp))
427		return PTR_ERR(ipcp);
 
 
428
429	msq = container_of(ipcp, struct msg_queue, q_perm);
430
431	err = security_msg_queue_msgctl(msq, cmd);
432	if (err)
433		goto out_unlock;
434
435	switch (cmd) {
436	case IPC_RMID:
 
 
437		freeque(ns, ipcp);
438		goto out_up;
439	case IPC_SET:
440		if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
 
 
 
441		    !capable(CAP_SYS_RESOURCE)) {
442			err = -EPERM;
443			goto out_unlock;
444		}
445
446		msq->q_qbytes = msqid64.msg_qbytes;
 
 
 
 
 
447
448		ipc_update_perm(&msqid64.msg_perm, ipcp);
449		msq->q_ctime = get_seconds();
450		/* sleeping receivers might be excluded by
451		 * stricter permissions.
452		 */
453		expunge_all(msq, -EAGAIN);
454		/* sleeping senders might be able to send
 
455		 * due to a larger queue size.
456		 */
457		ss_wakeup(&msq->q_senders, 0);
458		break;
 
 
 
 
459	default:
460		err = -EINVAL;
 
461	}
462out_unlock:
463	msg_unlock(msq);
 
 
 
464out_up:
465	up_write(&msg_ids(ns).rw_mutex);
466	return err;
467}
468
469SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
470{
471	struct msg_queue *msq;
472	int err, version;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
473	struct ipc_namespace *ns;
 
 
474
475	if (msqid < 0 || cmd < 0)
476		return -EINVAL;
477
478	version = ipc_parse_version(&cmd);
479	ns = current->nsproxy->ipc_ns;
480
481	switch (cmd) {
482	case IPC_INFO:
483	case MSG_INFO:
484	{
485		struct msginfo msginfo;
486		int max_id;
487
488		if (!buf)
489			return -EFAULT;
490		/*
491		 * We must not return kernel stack data.
492		 * due to padding, it's not enough
493		 * to set all member fields.
494		 */
495		err = security_msg_queue_msgctl(NULL, cmd);
496		if (err)
497			return err;
498
499		memset(&msginfo, 0, sizeof(msginfo));
500		msginfo.msgmni = ns->msg_ctlmni;
501		msginfo.msgmax = ns->msg_ctlmax;
502		msginfo.msgmnb = ns->msg_ctlmnb;
503		msginfo.msgssz = MSGSSZ;
504		msginfo.msgseg = MSGSEG;
505		down_read(&msg_ids(ns).rw_mutex);
506		if (cmd == MSG_INFO) {
507			msginfo.msgpool = msg_ids(ns).in_use;
508			msginfo.msgmap = atomic_read(&ns->msg_hdrs);
509			msginfo.msgtql = atomic_read(&ns->msg_bytes);
510		} else {
511			msginfo.msgmap = MSGMAP;
512			msginfo.msgpool = MSGPOOL;
513			msginfo.msgtql = MSGTQL;
514		}
515		max_id = ipc_get_maxid(&msg_ids(ns));
516		up_read(&msg_ids(ns).rw_mutex);
517		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
518			return -EFAULT;
519		return (max_id < 0) ? 0 : max_id;
520	}
521	case MSG_STAT:	/* msqid is an index rather than a msg queue id */
 
522	case IPC_STAT:
523	{
524		struct msqid64_ds tbuf;
525		int success_return;
526
527		if (!buf)
 
 
 
528			return -EFAULT;
 
 
 
 
 
 
 
 
529
530		if (cmd == MSG_STAT) {
531			msq = msg_lock(ns, msqid);
532			if (IS_ERR(msq))
533				return PTR_ERR(msq);
534			success_return = msq->q_perm.id;
535		} else {
536			msq = msg_lock_check(ns, msqid);
537			if (IS_ERR(msq))
538				return PTR_ERR(msq);
539			success_return = 0;
540		}
541		err = -EACCES;
542		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
543			goto out_unlock;
544
545		err = security_msg_queue_msgctl(msq, cmd);
546		if (err)
547			goto out_unlock;
 
 
 
 
548
549		memset(&tbuf, 0, sizeof(tbuf));
 
 
 
 
550
551		kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm);
552		tbuf.msg_stime  = msq->q_stime;
553		tbuf.msg_rtime  = msq->q_rtime;
554		tbuf.msg_ctime  = msq->q_ctime;
555		tbuf.msg_cbytes = msq->q_cbytes;
556		tbuf.msg_qnum   = msq->q_qnum;
557		tbuf.msg_qbytes = msq->q_qbytes;
558		tbuf.msg_lspid  = msq->q_lspid;
559		tbuf.msg_lrpid  = msq->q_lrpid;
560		msg_unlock(msq);
561		if (copy_msqid_to_user(buf, &tbuf, version))
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
562			return -EFAULT;
563		return success_return;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
564	}
 
 
 
 
 
 
 
 
 
565	case IPC_SET:
 
 
 
566	case IPC_RMID:
567		err = msgctl_down(ns, msqid, cmd, buf, version);
568		return err;
569	default:
570		return  -EINVAL;
571	}
 
572
573out_unlock:
574	msg_unlock(msq);
575	return err;
 
 
 
 
 
 
 
 
 
 
 
 
 
576}
 
 
577
578static int testmsg(struct msg_msg *msg, long type, int mode)
579{
580	switch(mode)
581	{
582		case SEARCH_ANY:
 
 
 
583			return 1;
584		case SEARCH_LESSEQUAL:
585			if (msg->m_type <=type)
586				return 1;
587			break;
588		case SEARCH_EQUAL:
589			if (msg->m_type == type)
590				return 1;
591			break;
592		case SEARCH_NOTEQUAL:
593			if (msg->m_type != type)
594				return 1;
595			break;
596	}
597	return 0;
598}
599
600static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg)
 
601{
602	struct list_head *tmp;
603
604	tmp = msq->q_receivers.next;
605	while (tmp != &msq->q_receivers) {
606		struct msg_receiver *msr;
607
608		msr = list_entry(tmp, struct msg_receiver, r_list);
609		tmp = tmp->next;
610		if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
611		    !security_msg_queue_msgrcv(msq, msg, msr->r_tsk,
612					       msr->r_msgtype, msr->r_mode)) {
613
614			list_del(&msr->r_list);
615			if (msr->r_maxsize < msg->m_ts) {
616				msr->r_msg = NULL;
617				wake_up_process(msr->r_tsk);
618				smp_mb();
619				msr->r_msg = ERR_PTR(-E2BIG);
620			} else {
621				msr->r_msg = NULL;
622				msq->q_lrpid = task_pid_vnr(msr->r_tsk);
623				msq->q_rtime = get_seconds();
624				wake_up_process(msr->r_tsk);
625				smp_mb();
626				msr->r_msg = msg;
627
 
 
628				return 1;
629			}
630		}
631	}
 
632	return 0;
633}
634
635long do_msgsnd(int msqid, long mtype, void __user *mtext,
636		size_t msgsz, int msgflg)
637{
638	struct msg_queue *msq;
639	struct msg_msg *msg;
640	int err;
641	struct ipc_namespace *ns;
 
642
643	ns = current->nsproxy->ipc_ns;
644
645	if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
646		return -EINVAL;
647	if (mtype < 1)
648		return -EINVAL;
649
650	msg = load_msg(mtext, msgsz);
651	if (IS_ERR(msg))
652		return PTR_ERR(msg);
653
654	msg->m_type = mtype;
655	msg->m_ts = msgsz;
656
657	msq = msg_lock_check(ns, msqid);
 
658	if (IS_ERR(msq)) {
659		err = PTR_ERR(msq);
660		goto out_free;
661	}
662
 
 
663	for (;;) {
664		struct msg_sender s;
665
666		err = -EACCES;
667		if (ipcperms(ns, &msq->q_perm, S_IWUGO))
668			goto out_unlock_free;
 
 
 
 
 
 
669
670		err = security_msg_queue_msgsnd(msq, msg, msgflg);
671		if (err)
672			goto out_unlock_free;
673
674		if (msgsz + msq->q_cbytes <= msq->q_qbytes &&
675				1 + msq->q_qnum <= msq->q_qbytes) {
676			break;
677		}
678
679		/* queue full, wait: */
680		if (msgflg & IPC_NOWAIT) {
681			err = -EAGAIN;
682			goto out_unlock_free;
683		}
684		ss_add(msq, &s);
685		ipc_rcu_getref(msq);
686		msg_unlock(msq);
 
 
 
 
 
 
 
 
687		schedule();
688
689		ipc_lock_by_ptr(&msq->q_perm);
690		ipc_rcu_putref(msq);
691		if (msq->q_perm.deleted) {
 
 
 
692			err = -EIDRM;
693			goto out_unlock_free;
694		}
695		ss_del(&s);
696
697		if (signal_pending(current)) {
698			err = -ERESTARTNOHAND;
699			goto out_unlock_free;
700		}
 
701	}
702
703	msq->q_lspid = task_tgid_vnr(current);
704	msq->q_stime = get_seconds();
705
706	if (!pipelined_send(msq, msg)) {
707		/* no one is waiting for this message, enqueue it */
708		list_add_tail(&msg->m_list, &msq->q_messages);
709		msq->q_cbytes += msgsz;
710		msq->q_qnum++;
711		atomic_add(msgsz, &ns->msg_bytes);
712		atomic_inc(&ns->msg_hdrs);
713	}
714
715	err = 0;
716	msg = NULL;
717
718out_unlock_free:
719	msg_unlock(msq);
720out_free:
 
 
721	if (msg != NULL)
722		free_msg(msg);
723	return err;
724}
725
726SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
727		int, msgflg)
728{
729	long mtype;
730
731	if (get_user(mtype, &msgp->mtype))
732		return -EFAULT;
733	return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
734}
735
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
736static inline int convert_mode(long *msgtyp, int msgflg)
737{
 
 
738	/*
739	 *  find message of correct type.
740	 *  msgtyp = 0 => get first.
741	 *  msgtyp > 0 => get first message of matching type.
742	 *  msgtyp < 0 => get message with least type must be < abs(msgtype).
743	 */
744	if (*msgtyp == 0)
745		return SEARCH_ANY;
746	if (*msgtyp < 0) {
747		*msgtyp = -*msgtyp;
 
 
 
748		return SEARCH_LESSEQUAL;
749	}
750	if (msgflg & MSG_EXCEPT)
751		return SEARCH_NOTEQUAL;
752	return SEARCH_EQUAL;
753}
754
755long do_msgrcv(int msqid, long *pmtype, void __user *mtext,
756		size_t msgsz, long msgtyp, int msgflg)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
757{
758	struct msg_queue *msq;
759	struct msg_msg *msg;
760	int mode;
 
761	struct ipc_namespace *ns;
 
 
 
 
762
763	if (msqid < 0 || (long) msgsz < 0)
764		return -EINVAL;
 
 
 
 
 
 
 
 
765	mode = convert_mode(&msgtyp, msgflg);
766	ns = current->nsproxy->ipc_ns;
767
768	msq = msg_lock_check(ns, msqid);
769	if (IS_ERR(msq))
 
 
 
770		return PTR_ERR(msq);
 
771
772	for (;;) {
773		struct msg_receiver msr_d;
774		struct list_head *tmp;
775
776		msg = ERR_PTR(-EACCES);
777		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
778			goto out_unlock;
779
780		msg = ERR_PTR(-EAGAIN);
781		tmp = msq->q_messages.next;
782		while (tmp != &msq->q_messages) {
783			struct msg_msg *walk_msg;
784
785			walk_msg = list_entry(tmp, struct msg_msg, m_list);
786			if (testmsg(walk_msg, msgtyp, mode) &&
787			    !security_msg_queue_msgrcv(msq, walk_msg, current,
788						       msgtyp, mode)) {
789
790				msg = walk_msg;
791				if (mode == SEARCH_LESSEQUAL &&
792						walk_msg->m_type != 1) {
793					msg = walk_msg;
794					msgtyp = walk_msg->m_type - 1;
795				} else {
796					msg = walk_msg;
797					break;
798				}
799			}
800			tmp = tmp->next;
801		}
 
 
802		if (!IS_ERR(msg)) {
803			/*
804			 * Found a suitable message.
805			 * Unlink it from the queue.
806			 */
807			if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
808				msg = ERR_PTR(-E2BIG);
809				goto out_unlock;
 
 
 
 
 
 
 
 
810			}
 
811			list_del(&msg->m_list);
812			msq->q_qnum--;
813			msq->q_rtime = get_seconds();
814			msq->q_lrpid = task_tgid_vnr(current);
815			msq->q_cbytes -= msg->m_ts;
816			atomic_sub(msg->m_ts, &ns->msg_bytes);
817			atomic_dec(&ns->msg_hdrs);
818			ss_wakeup(&msq->q_senders, 0);
819			msg_unlock(msq);
820			break;
821		}
 
822		/* No message waiting. Wait for a message */
823		if (msgflg & IPC_NOWAIT) {
824			msg = ERR_PTR(-ENOMSG);
825			goto out_unlock;
826		}
 
827		list_add_tail(&msr_d.r_list, &msq->q_receivers);
828		msr_d.r_tsk = current;
829		msr_d.r_msgtype = msgtyp;
830		msr_d.r_mode = mode;
831		if (msgflg & MSG_NOERROR)
832			msr_d.r_maxsize = INT_MAX;
833		else
834			msr_d.r_maxsize = msgsz;
835		msr_d.r_msg = ERR_PTR(-EAGAIN);
836		current->state = TASK_INTERRUPTIBLE;
837		msg_unlock(msq);
838
 
 
 
 
 
 
 
 
839		schedule();
840
841		/* Lockless receive, part 1:
842		 * Disable preemption.  We don't hold a reference to the queue
843		 * and getting a reference would defeat the idea of a lockless
844		 * operation, thus the code relies on rcu to guarantee the
845		 * existence of msq:
 
846		 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
847		 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
848		 * rcu_read_lock() prevents preemption between reading r_msg
849		 * and the spin_lock() inside ipc_lock_by_ptr().
850		 */
851		rcu_read_lock();
852
853		/* Lockless receive, part 2:
854		 * Wait until pipelined_send or expunge_all are outside of
855		 * wake_up_process(). There is a race with exit(), see
856		 * ipc/mqueue.c for the details.
857		 */
858		msg = (struct msg_msg*)msr_d.r_msg;
859		while (msg == NULL) {
860			cpu_relax();
861			msg = (struct msg_msg *)msr_d.r_msg;
862		}
863
864		/* Lockless receive, part 3:
865		 * If there is a message or an error then accept it without
866		 * locking.
867		 */
 
868		if (msg != ERR_PTR(-EAGAIN)) {
869			rcu_read_unlock();
870			break;
 
 
871		}
872
873		/* Lockless receive, part 3:
874		 * Acquire the queue spinlock.
875		 */
876		ipc_lock_by_ptr(&msq->q_perm);
877		rcu_read_unlock();
878
879		/* Lockless receive, part 4:
880		 * Repeat test after acquiring the spinlock.
881		 */
882		msg = (struct msg_msg*)msr_d.r_msg;
883		if (msg != ERR_PTR(-EAGAIN))
884			goto out_unlock;
885
886		list_del(&msr_d.r_list);
887		if (signal_pending(current)) {
888			msg = ERR_PTR(-ERESTARTNOHAND);
889out_unlock:
890			msg_unlock(msq);
891			break;
892		}
 
 
893	}
894	if (IS_ERR(msg))
895		return PTR_ERR(msg);
896
897	msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz;
898	*pmtype = msg->m_type;
899	if (store_msg(mtext, msg, msgsz))
900		msgsz = -EFAULT;
 
 
 
 
 
901
 
902	free_msg(msg);
903
904	return msgsz;
 
 
 
 
 
 
905}
906
907SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
908		long, msgtyp, int, msgflg)
909{
910	long err, mtype;
 
911
912	err =  do_msgrcv(msqid, &mtype, msgp->mtext, msgsz, msgtyp, msgflg);
913	if (err < 0)
914		goto out;
915
916	if (put_user(mtype, &msgp->mtype))
917		err = -EFAULT;
918out:
919	return err;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
920}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
921
922#ifdef CONFIG_PROC_FS
923static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
924{
925	struct msg_queue *msq = it;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
926
927	return seq_printf(s,
928			"%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n",
929			msq->q_perm.key,
930			msq->q_perm.id,
931			msq->q_perm.mode,
932			msq->q_cbytes,
933			msq->q_qnum,
934			msq->q_lspid,
935			msq->q_lrpid,
936			msq->q_perm.uid,
937			msq->q_perm.gid,
938			msq->q_perm.cuid,
939			msq->q_perm.cgid,
940			msq->q_stime,
941			msq->q_rtime,
942			msq->q_ctime);
943}
944#endif
v6.2
   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#include <linux/percpu_counter.h>
  43
  44#include <asm/current.h>
  45#include <linux/uaccess.h>
  46#include "util.h"
  47
  48/* one msq_queue structure for each present queue on the system */
  49struct msg_queue {
  50	struct kern_ipc_perm q_perm;
  51	time64_t q_stime;		/* last msgsnd time */
  52	time64_t q_rtime;		/* last msgrcv time */
  53	time64_t q_ctime;		/* last change time */
  54	unsigned long q_cbytes;		/* current number of bytes on queue */
  55	unsigned long q_qnum;		/* number of messages in queue */
  56	unsigned long q_qbytes;		/* max number of bytes on queue */
  57	struct pid *q_lspid;		/* pid of last msgsnd */
  58	struct pid *q_lrpid;		/* last receive pid */
  59
  60	struct list_head q_messages;
  61	struct list_head q_receivers;
  62	struct list_head q_senders;
  63} __randomize_layout;
  64
  65/*
  66 * MSG_BARRIER Locking:
  67 *
  68 * Similar to the optimization used in ipc/mqueue.c, one syscall return path
  69 * does not acquire any locks when it sees that a message exists in
  70 * msg_receiver.r_msg. Therefore r_msg is set using smp_store_release()
  71 * and accessed using READ_ONCE()+smp_acquire__after_ctrl_dep(). In addition,
  72 * wake_q_add_safe() is used. See ipc/mqueue.c for more details
  73 */
  74
  75/* one msg_receiver structure for each sleeping receiver */
  76struct msg_receiver {
  77	struct list_head	r_list;
  78	struct task_struct	*r_tsk;
  79
  80	int			r_mode;
  81	long			r_msgtype;
  82	long			r_maxsize;
  83
  84	struct msg_msg		*r_msg;
  85};
  86
  87/* one msg_sender for each sleeping sender */
  88struct msg_sender {
  89	struct list_head	list;
  90	struct task_struct	*tsk;
  91	size_t                  msgsz;
  92};
  93
  94#define SEARCH_ANY		1
  95#define SEARCH_EQUAL		2
  96#define SEARCH_NOTEQUAL		3
  97#define SEARCH_LESSEQUAL	4
  98#define SEARCH_NUMBER		5
  99
 100#define msg_ids(ns)	((ns)->ids[IPC_MSG_IDS])
 101
 102static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 103{
 104	struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&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 struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
 113							int id)
 114{
 115	struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
 116
 117	if (IS_ERR(ipcp))
 118		return ERR_CAST(ipcp);
 119
 120	return container_of(ipcp, struct msg_queue, q_perm);
 121}
 122
 123static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
 124{
 125	ipc_rmid(&msg_ids(ns), &s->q_perm);
 126}
 127
 128static void msg_rcu_free(struct rcu_head *head)
 129{
 130	struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu);
 131	struct msg_queue *msq = container_of(p, struct msg_queue, q_perm);
 132
 133	security_msg_queue_free(&msq->q_perm);
 134	kfree(msq);
 135}
 136
 137/**
 138 * newque - Create a new msg queue
 139 * @ns: namespace
 140 * @params: ptr to the structure that contains the key and msgflg
 141 *
 142 * Called with msg_ids.rwsem held (writer)
 143 */
 144static int newque(struct ipc_namespace *ns, struct ipc_params *params)
 145{
 146	struct msg_queue *msq;
 147	int retval;
 148	key_t key = params->key;
 149	int msgflg = params->flg;
 150
 151	msq = kmalloc(sizeof(*msq), GFP_KERNEL_ACCOUNT);
 152	if (unlikely(!msq))
 153		return -ENOMEM;
 154
 155	msq->q_perm.mode = msgflg & S_IRWXUGO;
 156	msq->q_perm.key = key;
 157
 158	msq->q_perm.security = NULL;
 159	retval = security_msg_queue_alloc(&msq->q_perm);
 160	if (retval) {
 161		kfree(msq);
 162		return retval;
 163	}
 164
 
 
 
 
 
 
 
 
 
 
 165	msq->q_stime = msq->q_rtime = 0;
 166	msq->q_ctime = ktime_get_real_seconds();
 167	msq->q_cbytes = msq->q_qnum = 0;
 168	msq->q_qbytes = ns->msg_ctlmnb;
 169	msq->q_lspid = msq->q_lrpid = NULL;
 170	INIT_LIST_HEAD(&msq->q_messages);
 171	INIT_LIST_HEAD(&msq->q_receivers);
 172	INIT_LIST_HEAD(&msq->q_senders);
 173
 174	/* ipc_addid() locks msq upon success. */
 175	retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
 176	if (retval < 0) {
 177		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 178		return retval;
 179	}
 180
 181	ipc_unlock_object(&msq->q_perm);
 182	rcu_read_unlock();
 183
 184	return msq->q_perm.id;
 185}
 186
 187static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz)
 188{
 189	return msgsz + msq->q_cbytes <= msq->q_qbytes &&
 190		1 + msq->q_qnum <= msq->q_qbytes;
 191}
 192
 193static inline void ss_add(struct msg_queue *msq,
 194			  struct msg_sender *mss, size_t msgsz)
 195{
 196	mss->tsk = current;
 197	mss->msgsz = msgsz;
 198	/*
 199	 * No memory barrier required: we did ipc_lock_object(),
 200	 * and the waker obtains that lock before calling wake_q_add().
 201	 */
 202	__set_current_state(TASK_INTERRUPTIBLE);
 203	list_add_tail(&mss->list, &msq->q_senders);
 204}
 205
 206static inline void ss_del(struct msg_sender *mss)
 207{
 208	if (mss->list.next)
 209		list_del(&mss->list);
 210}
 211
 212static void ss_wakeup(struct msg_queue *msq,
 213		      struct wake_q_head *wake_q, bool kill)
 214{
 215	struct msg_sender *mss, *t;
 216	struct task_struct *stop_tsk = NULL;
 217	struct list_head *h = &msq->q_senders;
 218
 219	list_for_each_entry_safe(mss, t, h, list) {
 
 
 
 
 
 220		if (kill)
 221			mss->list.next = NULL;
 222
 223		/*
 224		 * Stop at the first task we don't wakeup,
 225		 * we've already iterated the original
 226		 * sender queue.
 227		 */
 228		else if (stop_tsk == mss->tsk)
 229			break;
 230		/*
 231		 * We are not in an EIDRM scenario here, therefore
 232		 * verify that we really need to wakeup the task.
 233		 * To maintain current semantics and wakeup order,
 234		 * move the sender to the tail on behalf of the
 235		 * blocked task.
 236		 */
 237		else if (!msg_fits_inqueue(msq, mss->msgsz)) {
 238			if (!stop_tsk)
 239				stop_tsk = mss->tsk;
 240
 241			list_move_tail(&mss->list, &msq->q_senders);
 242			continue;
 243		}
 244
 245		wake_q_add(wake_q, mss->tsk);
 246	}
 247}
 248
 249static void expunge_all(struct msg_queue *msq, int res,
 250			struct wake_q_head *wake_q)
 251{
 252	struct msg_receiver *msr, *t;
 253
 254	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 255		struct task_struct *r_tsk;
 
 256
 257		r_tsk = get_task_struct(msr->r_tsk);
 258
 259		/* see MSG_BARRIER for purpose/pairing */
 260		smp_store_release(&msr->r_msg, ERR_PTR(res));
 261		wake_q_add_safe(wake_q, r_tsk);
 
 262	}
 263}
 264
 265/*
 266 * freeque() wakes up waiters on the sender and receiver waiting queue,
 267 * removes the message queue from message queue ID IDR, and cleans up all the
 268 * messages associated with this queue.
 269 *
 270 * msg_ids.rwsem (writer) and the spinlock for this message queue are held
 271 * before freeque() is called. msg_ids.rwsem remains locked on exit.
 272 */
 273static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 274	__releases(RCU)
 275	__releases(&msq->q_perm)
 276{
 277	struct msg_msg *msg, *t;
 278	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
 279	DEFINE_WAKE_Q(wake_q);
 280
 281	expunge_all(msq, -EIDRM, &wake_q);
 282	ss_wakeup(msq, &wake_q, true);
 283	msg_rmid(ns, msq);
 284	ipc_unlock_object(&msq->q_perm);
 285	wake_up_q(&wake_q);
 286	rcu_read_unlock();
 
 
 287
 288	list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
 289		percpu_counter_sub_local(&ns->percpu_msg_hdrs, 1);
 290		free_msg(msg);
 291	}
 292	percpu_counter_sub_local(&ns->percpu_msg_bytes, msq->q_cbytes);
 293	ipc_update_pid(&msq->q_lspid, NULL);
 294	ipc_update_pid(&msq->q_lrpid, NULL);
 295	ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 296}
 297
 298long ksys_msgget(key_t key, int msgflg)
 
 
 
 
 
 
 
 
 
 
 299{
 300	struct ipc_namespace *ns;
 301	static const struct ipc_ops msg_ops = {
 302		.getnew = newque,
 303		.associate = security_msg_queue_associate,
 304	};
 305	struct ipc_params msg_params;
 306
 307	ns = current->nsproxy->ipc_ns;
 308
 
 
 
 
 309	msg_params.key = key;
 310	msg_params.flg = msgflg;
 311
 312	return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
 313}
 314
 315SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
 316{
 317	return ksys_msgget(key, msgflg);
 318}
 319
 320static inline unsigned long
 321copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
 322{
 323	switch (version) {
 324	case IPC_64:
 325		return copy_to_user(buf, in, sizeof(*in));
 326	case IPC_OLD:
 327	{
 328		struct msqid_ds out;
 329
 330		memset(&out, 0, sizeof(out));
 331
 332		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
 333
 334		out.msg_stime		= in->msg_stime;
 335		out.msg_rtime		= in->msg_rtime;
 336		out.msg_ctime		= in->msg_ctime;
 337
 338		if (in->msg_cbytes > USHRT_MAX)
 339			out.msg_cbytes	= USHRT_MAX;
 340		else
 341			out.msg_cbytes	= in->msg_cbytes;
 342		out.msg_lcbytes		= in->msg_cbytes;
 343
 344		if (in->msg_qnum > USHRT_MAX)
 345			out.msg_qnum	= USHRT_MAX;
 346		else
 347			out.msg_qnum	= in->msg_qnum;
 348
 349		if (in->msg_qbytes > USHRT_MAX)
 350			out.msg_qbytes	= USHRT_MAX;
 351		else
 352			out.msg_qbytes	= in->msg_qbytes;
 353		out.msg_lqbytes		= in->msg_qbytes;
 354
 355		out.msg_lspid		= in->msg_lspid;
 356		out.msg_lrpid		= in->msg_lrpid;
 357
 358		return copy_to_user(buf, &out, sizeof(out));
 359	}
 360	default:
 361		return -EINVAL;
 362	}
 363}
 364
 365static inline unsigned long
 366copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
 367{
 368	switch (version) {
 369	case IPC_64:
 370		if (copy_from_user(out, buf, sizeof(*out)))
 371			return -EFAULT;
 372		return 0;
 373	case IPC_OLD:
 374	{
 375		struct msqid_ds tbuf_old;
 376
 377		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 378			return -EFAULT;
 379
 380		out->msg_perm.uid	= tbuf_old.msg_perm.uid;
 381		out->msg_perm.gid	= tbuf_old.msg_perm.gid;
 382		out->msg_perm.mode	= tbuf_old.msg_perm.mode;
 383
 384		if (tbuf_old.msg_qbytes == 0)
 385			out->msg_qbytes	= tbuf_old.msg_lqbytes;
 386		else
 387			out->msg_qbytes	= tbuf_old.msg_qbytes;
 388
 389		return 0;
 390	}
 391	default:
 392		return -EINVAL;
 393	}
 394}
 395
 396/*
 397 * This function handles some msgctl commands which require the rwsem
 398 * to be held in write mode.
 399 * NOTE: no locks must be held, the rwsem is taken inside this function.
 400 */
 401static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
 402			struct ipc64_perm *perm, int msg_qbytes)
 403{
 404	struct kern_ipc_perm *ipcp;
 
 405	struct msg_queue *msq;
 406	int err;
 407
 408	down_write(&msg_ids(ns).rwsem);
 409	rcu_read_lock();
 
 
 410
 411	ipcp = ipcctl_obtain_check(ns, &msg_ids(ns), msqid, cmd,
 412				      perm, msg_qbytes);
 413	if (IS_ERR(ipcp)) {
 414		err = PTR_ERR(ipcp);
 415		goto out_unlock1;
 416	}
 417
 418	msq = container_of(ipcp, struct msg_queue, q_perm);
 419
 420	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
 421	if (err)
 422		goto out_unlock1;
 423
 424	switch (cmd) {
 425	case IPC_RMID:
 426		ipc_lock_object(&msq->q_perm);
 427		/* freeque unlocks the ipc object and rcu */
 428		freeque(ns, ipcp);
 429		goto out_up;
 430	case IPC_SET:
 431	{
 432		DEFINE_WAKE_Q(wake_q);
 433
 434		if (msg_qbytes > ns->msg_ctlmnb &&
 435		    !capable(CAP_SYS_RESOURCE)) {
 436			err = -EPERM;
 437			goto out_unlock1;
 438		}
 439
 440		ipc_lock_object(&msq->q_perm);
 441		err = ipc_update_perm(perm, ipcp);
 442		if (err)
 443			goto out_unlock0;
 444
 445		msq->q_qbytes = msg_qbytes;
 446
 447		msq->q_ctime = ktime_get_real_seconds();
 448		/*
 449		 * Sleeping receivers might be excluded by
 450		 * stricter permissions.
 451		 */
 452		expunge_all(msq, -EAGAIN, &wake_q);
 453		/*
 454		 * Sleeping senders might be able to send
 455		 * due to a larger queue size.
 456		 */
 457		ss_wakeup(msq, &wake_q, false);
 458		ipc_unlock_object(&msq->q_perm);
 459		wake_up_q(&wake_q);
 460
 461		goto out_unlock1;
 462	}
 463	default:
 464		err = -EINVAL;
 465		goto out_unlock1;
 466	}
 467
 468out_unlock0:
 469	ipc_unlock_object(&msq->q_perm);
 470out_unlock1:
 471	rcu_read_unlock();
 472out_up:
 473	up_write(&msg_ids(ns).rwsem);
 474	return err;
 475}
 476
 477static int msgctl_info(struct ipc_namespace *ns, int msqid,
 478			 int cmd, struct msginfo *msginfo)
 479{
 480	int err;
 481	int max_idx;
 482
 483	/*
 484	 * We must not return kernel stack data.
 485	 * due to padding, it's not enough
 486	 * to set all member fields.
 487	 */
 488	err = security_msg_queue_msgctl(NULL, cmd);
 489	if (err)
 490		return err;
 491
 492	memset(msginfo, 0, sizeof(*msginfo));
 493	msginfo->msgmni = ns->msg_ctlmni;
 494	msginfo->msgmax = ns->msg_ctlmax;
 495	msginfo->msgmnb = ns->msg_ctlmnb;
 496	msginfo->msgssz = MSGSSZ;
 497	msginfo->msgseg = MSGSEG;
 498	down_read(&msg_ids(ns).rwsem);
 499	if (cmd == MSG_INFO)
 500		msginfo->msgpool = msg_ids(ns).in_use;
 501	max_idx = ipc_get_maxidx(&msg_ids(ns));
 502	up_read(&msg_ids(ns).rwsem);
 503	if (cmd == MSG_INFO) {
 504		msginfo->msgmap = min_t(int,
 505				     percpu_counter_sum(&ns->percpu_msg_hdrs),
 506				     INT_MAX);
 507		msginfo->msgtql = min_t(int,
 508		                     percpu_counter_sum(&ns->percpu_msg_bytes),
 509				     INT_MAX);
 510	} else {
 511		msginfo->msgmap = MSGMAP;
 512		msginfo->msgpool = MSGPOOL;
 513		msginfo->msgtql = MSGTQL;
 514	}
 515	return (max_idx < 0) ? 0 : max_idx;
 516}
 517
 518static int msgctl_stat(struct ipc_namespace *ns, int msqid,
 519			 int cmd, struct msqid64_ds *p)
 520{
 521	struct msg_queue *msq;
 522	int err;
 523
 524	memset(p, 0, sizeof(*p));
 525
 526	rcu_read_lock();
 527	if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {
 528		msq = msq_obtain_object(ns, msqid);
 529		if (IS_ERR(msq)) {
 530			err = PTR_ERR(msq);
 531			goto out_unlock;
 532		}
 533	} else { /* IPC_STAT */
 534		msq = msq_obtain_object_check(ns, msqid);
 535		if (IS_ERR(msq)) {
 536			err = PTR_ERR(msq);
 537			goto out_unlock;
 538		}
 539	}
 540
 541	/* see comment for SHM_STAT_ANY */
 542	if (cmd == MSG_STAT_ANY)
 543		audit_ipc_obj(&msq->q_perm);
 544	else {
 545		err = -EACCES;
 546		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
 547			goto out_unlock;
 548	}
 549
 550	err = security_msg_queue_msgctl(&msq->q_perm, cmd);
 551	if (err)
 552		goto out_unlock;
 553
 554	ipc_lock_object(&msq->q_perm);
 555
 556	if (!ipc_valid_object(&msq->q_perm)) {
 557		ipc_unlock_object(&msq->q_perm);
 558		err = -EIDRM;
 559		goto out_unlock;
 560	}
 561
 562	kernel_to_ipc64_perm(&msq->q_perm, &p->msg_perm);
 563	p->msg_stime  = msq->q_stime;
 564	p->msg_rtime  = msq->q_rtime;
 565	p->msg_ctime  = msq->q_ctime;
 566#ifndef CONFIG_64BIT
 567	p->msg_stime_high = msq->q_stime >> 32;
 568	p->msg_rtime_high = msq->q_rtime >> 32;
 569	p->msg_ctime_high = msq->q_ctime >> 32;
 570#endif
 571	p->msg_cbytes = msq->q_cbytes;
 572	p->msg_qnum   = msq->q_qnum;
 573	p->msg_qbytes = msq->q_qbytes;
 574	p->msg_lspid  = pid_vnr(msq->q_lspid);
 575	p->msg_lrpid  = pid_vnr(msq->q_lrpid);
 576
 577	if (cmd == IPC_STAT) {
 578		/*
 579		 * As defined in SUS:
 580		 * Return 0 on success
 581		 */
 582		err = 0;
 583	} else {
 584		/*
 585		 * MSG_STAT and MSG_STAT_ANY (both Linux specific)
 586		 * Return the full id, including the sequence number
 587		 */
 588		err = msq->q_perm.id;
 589	}
 590
 591	ipc_unlock_object(&msq->q_perm);
 592out_unlock:
 593	rcu_read_unlock();
 594	return err;
 595}
 596
 597static long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf, int version)
 598{
 599	struct ipc_namespace *ns;
 600	struct msqid64_ds msqid64;
 601	int err;
 602
 603	if (msqid < 0 || cmd < 0)
 604		return -EINVAL;
 605
 
 606	ns = current->nsproxy->ipc_ns;
 607
 608	switch (cmd) {
 609	case IPC_INFO:
 610	case MSG_INFO: {
 
 611		struct msginfo msginfo;
 612		err = msgctl_info(ns, msqid, cmd, &msginfo);
 613		if (err < 0)
 
 
 
 
 
 
 
 
 
 614			return err;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 615		if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
 616			err = -EFAULT;
 617		return err;
 618	}
 619	case MSG_STAT:	/* msqid is an index rather than a msg queue id */
 620	case MSG_STAT_ANY:
 621	case IPC_STAT:
 622		err = msgctl_stat(ns, msqid, cmd, &msqid64);
 623		if (err < 0)
 624			return err;
 625		if (copy_msqid_to_user(buf, &msqid64, version))
 626			err = -EFAULT;
 627		return err;
 628	case IPC_SET:
 629		if (copy_msqid_from_user(&msqid64, buf, version))
 630			return -EFAULT;
 631		return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm,
 632				   msqid64.msg_qbytes);
 633	case IPC_RMID:
 634		return msgctl_down(ns, msqid, cmd, NULL, 0);
 635	default:
 636		return  -EINVAL;
 637	}
 638}
 639
 640SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 641{
 642	return ksys_msgctl(msqid, cmd, buf, IPC_64);
 643}
 
 
 
 
 
 
 
 
 
 
 644
 645#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 646long ksys_old_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
 647{
 648	int version = ipc_parse_version(&cmd);
 649
 650	return ksys_msgctl(msqid, cmd, buf, version);
 651}
 652
 653SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
 654{
 655	return ksys_old_msgctl(msqid, cmd, buf);
 656}
 657#endif
 658
 659#ifdef CONFIG_COMPAT
 660
 661struct compat_msqid_ds {
 662	struct compat_ipc_perm msg_perm;
 663	compat_uptr_t msg_first;
 664	compat_uptr_t msg_last;
 665	old_time32_t msg_stime;
 666	old_time32_t msg_rtime;
 667	old_time32_t msg_ctime;
 668	compat_ulong_t msg_lcbytes;
 669	compat_ulong_t msg_lqbytes;
 670	unsigned short msg_cbytes;
 671	unsigned short msg_qnum;
 672	unsigned short msg_qbytes;
 673	compat_ipc_pid_t msg_lspid;
 674	compat_ipc_pid_t msg_lrpid;
 675};
 676
 677static int copy_compat_msqid_from_user(struct msqid64_ds *out, void __user *buf,
 678					int version)
 679{
 680	memset(out, 0, sizeof(*out));
 681	if (version == IPC_64) {
 682		struct compat_msqid64_ds __user *p = buf;
 683		if (get_compat_ipc64_perm(&out->msg_perm, &p->msg_perm))
 684			return -EFAULT;
 685		if (get_user(out->msg_qbytes, &p->msg_qbytes))
 686			return -EFAULT;
 687	} else {
 688		struct compat_msqid_ds __user *p = buf;
 689		if (get_compat_ipc_perm(&out->msg_perm, &p->msg_perm))
 690			return -EFAULT;
 691		if (get_user(out->msg_qbytes, &p->msg_qbytes))
 692			return -EFAULT;
 693	}
 694	return 0;
 695}
 696
 697static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
 698					int version)
 699{
 700	if (version == IPC_64) {
 701		struct compat_msqid64_ds v;
 702		memset(&v, 0, sizeof(v));
 703		to_compat_ipc64_perm(&v.msg_perm, &in->msg_perm);
 704		v.msg_stime	 = lower_32_bits(in->msg_stime);
 705		v.msg_stime_high = upper_32_bits(in->msg_stime);
 706		v.msg_rtime	 = lower_32_bits(in->msg_rtime);
 707		v.msg_rtime_high = upper_32_bits(in->msg_rtime);
 708		v.msg_ctime	 = lower_32_bits(in->msg_ctime);
 709		v.msg_ctime_high = upper_32_bits(in->msg_ctime);
 710		v.msg_cbytes = in->msg_cbytes;
 711		v.msg_qnum = in->msg_qnum;
 712		v.msg_qbytes = in->msg_qbytes;
 713		v.msg_lspid = in->msg_lspid;
 714		v.msg_lrpid = in->msg_lrpid;
 715		return copy_to_user(buf, &v, sizeof(v));
 716	} else {
 717		struct compat_msqid_ds v;
 718		memset(&v, 0, sizeof(v));
 719		to_compat_ipc_perm(&v.msg_perm, &in->msg_perm);
 720		v.msg_stime = in->msg_stime;
 721		v.msg_rtime = in->msg_rtime;
 722		v.msg_ctime = in->msg_ctime;
 723		v.msg_cbytes = in->msg_cbytes;
 724		v.msg_qnum = in->msg_qnum;
 725		v.msg_qbytes = in->msg_qbytes;
 726		v.msg_lspid = in->msg_lspid;
 727		v.msg_lrpid = in->msg_lrpid;
 728		return copy_to_user(buf, &v, sizeof(v));
 729	}
 730}
 731
 732static long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr, int version)
 733{
 734	struct ipc_namespace *ns;
 735	int err;
 736	struct msqid64_ds msqid64;
 737
 738	ns = current->nsproxy->ipc_ns;
 739
 740	if (msqid < 0 || cmd < 0)
 741		return -EINVAL;
 742
 743	switch (cmd & (~IPC_64)) {
 744	case IPC_INFO:
 745	case MSG_INFO: {
 746		struct msginfo msginfo;
 747		err = msgctl_info(ns, msqid, cmd, &msginfo);
 748		if (err < 0)
 749			return err;
 750		if (copy_to_user(uptr, &msginfo, sizeof(struct msginfo)))
 751			err = -EFAULT;
 752		return err;
 753	}
 754	case IPC_STAT:
 755	case MSG_STAT:
 756	case MSG_STAT_ANY:
 757		err = msgctl_stat(ns, msqid, cmd, &msqid64);
 758		if (err < 0)
 759			return err;
 760		if (copy_compat_msqid_to_user(uptr, &msqid64, version))
 761			err = -EFAULT;
 762		return err;
 763	case IPC_SET:
 764		if (copy_compat_msqid_from_user(&msqid64, uptr, version))
 765			return -EFAULT;
 766		return msgctl_down(ns, msqid, cmd, &msqid64.msg_perm, msqid64.msg_qbytes);
 767	case IPC_RMID:
 768		return msgctl_down(ns, msqid, cmd, NULL, 0);
 
 769	default:
 770		return -EINVAL;
 771	}
 772}
 773
 774COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
 775{
 776	return compat_ksys_msgctl(msqid, cmd, uptr, IPC_64);
 777}
 778
 779#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
 780long compat_ksys_old_msgctl(int msqid, int cmd, void __user *uptr)
 781{
 782	int version = compat_ipc_parse_version(&cmd);
 783
 784	return compat_ksys_msgctl(msqid, cmd, uptr, version);
 785}
 786
 787COMPAT_SYSCALL_DEFINE3(old_msgctl, int, msqid, int, cmd, void __user *, uptr)
 788{
 789	return compat_ksys_old_msgctl(msqid, cmd, uptr);
 790}
 791#endif
 792#endif
 793
 794static int testmsg(struct msg_msg *msg, long type, int mode)
 795{
 796	switch (mode) {
 797	case SEARCH_ANY:
 798	case SEARCH_NUMBER:
 799		return 1;
 800	case SEARCH_LESSEQUAL:
 801		if (msg->m_type <= type)
 802			return 1;
 803		break;
 804	case SEARCH_EQUAL:
 805		if (msg->m_type == type)
 806			return 1;
 807		break;
 808	case SEARCH_NOTEQUAL:
 809		if (msg->m_type != type)
 810			return 1;
 811		break;
 
 
 
 812	}
 813	return 0;
 814}
 815
 816static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg,
 817				 struct wake_q_head *wake_q)
 818{
 819	struct msg_receiver *msr, *t;
 
 
 
 
 820
 821	list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
 
 822		if (testmsg(msg, msr->r_msgtype, msr->r_mode) &&
 823		    !security_msg_queue_msgrcv(&msq->q_perm, msg, msr->r_tsk,
 824					       msr->r_msgtype, msr->r_mode)) {
 825
 826			list_del(&msr->r_list);
 827			if (msr->r_maxsize < msg->m_ts) {
 828				wake_q_add(wake_q, msr->r_tsk);
 829
 830				/* See expunge_all regarding memory barrier */
 831				smp_store_release(&msr->r_msg, ERR_PTR(-E2BIG));
 832			} else {
 833				ipc_update_pid(&msq->q_lrpid, task_pid(msr->r_tsk));
 834				msq->q_rtime = ktime_get_real_seconds();
 835
 836				wake_q_add(wake_q, msr->r_tsk);
 
 
 837
 838				/* See expunge_all regarding memory barrier */
 839				smp_store_release(&msr->r_msg, msg);
 840				return 1;
 841			}
 842		}
 843	}
 844
 845	return 0;
 846}
 847
 848static long do_msgsnd(int msqid, long mtype, void __user *mtext,
 849		size_t msgsz, int msgflg)
 850{
 851	struct msg_queue *msq;
 852	struct msg_msg *msg;
 853	int err;
 854	struct ipc_namespace *ns;
 855	DEFINE_WAKE_Q(wake_q);
 856
 857	ns = current->nsproxy->ipc_ns;
 858
 859	if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
 860		return -EINVAL;
 861	if (mtype < 1)
 862		return -EINVAL;
 863
 864	msg = load_msg(mtext, msgsz);
 865	if (IS_ERR(msg))
 866		return PTR_ERR(msg);
 867
 868	msg->m_type = mtype;
 869	msg->m_ts = msgsz;
 870
 871	rcu_read_lock();
 872	msq = msq_obtain_object_check(ns, msqid);
 873	if (IS_ERR(msq)) {
 874		err = PTR_ERR(msq);
 875		goto out_unlock1;
 876	}
 877
 878	ipc_lock_object(&msq->q_perm);
 879
 880	for (;;) {
 881		struct msg_sender s;
 882
 883		err = -EACCES;
 884		if (ipcperms(ns, &msq->q_perm, S_IWUGO))
 885			goto out_unlock0;
 886
 887		/* raced with RMID? */
 888		if (!ipc_valid_object(&msq->q_perm)) {
 889			err = -EIDRM;
 890			goto out_unlock0;
 891		}
 892
 893		err = security_msg_queue_msgsnd(&msq->q_perm, msg, msgflg);
 894		if (err)
 895			goto out_unlock0;
 896
 897		if (msg_fits_inqueue(msq, msgsz))
 
 898			break;
 
 899
 900		/* queue full, wait: */
 901		if (msgflg & IPC_NOWAIT) {
 902			err = -EAGAIN;
 903			goto out_unlock0;
 904		}
 905
 906		/* enqueue the sender and prepare to block */
 907		ss_add(msq, &s, msgsz);
 908
 909		if (!ipc_rcu_getref(&msq->q_perm)) {
 910			err = -EIDRM;
 911			goto out_unlock0;
 912		}
 913
 914		ipc_unlock_object(&msq->q_perm);
 915		rcu_read_unlock();
 916		schedule();
 917
 918		rcu_read_lock();
 919		ipc_lock_object(&msq->q_perm);
 920
 921		ipc_rcu_putref(&msq->q_perm, msg_rcu_free);
 922		/* raced with RMID? */
 923		if (!ipc_valid_object(&msq->q_perm)) {
 924			err = -EIDRM;
 925			goto out_unlock0;
 926		}
 927		ss_del(&s);
 928
 929		if (signal_pending(current)) {
 930			err = -ERESTARTNOHAND;
 931			goto out_unlock0;
 932		}
 933
 934	}
 935
 936	ipc_update_pid(&msq->q_lspid, task_tgid(current));
 937	msq->q_stime = ktime_get_real_seconds();
 938
 939	if (!pipelined_send(msq, msg, &wake_q)) {
 940		/* no one is waiting for this message, enqueue it */
 941		list_add_tail(&msg->m_list, &msq->q_messages);
 942		msq->q_cbytes += msgsz;
 943		msq->q_qnum++;
 944		percpu_counter_add_local(&ns->percpu_msg_bytes, msgsz);
 945		percpu_counter_add_local(&ns->percpu_msg_hdrs, 1);
 946	}
 947
 948	err = 0;
 949	msg = NULL;
 950
 951out_unlock0:
 952	ipc_unlock_object(&msq->q_perm);
 953	wake_up_q(&wake_q);
 954out_unlock1:
 955	rcu_read_unlock();
 956	if (msg != NULL)
 957		free_msg(msg);
 958	return err;
 959}
 960
 961long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,
 962		 int msgflg)
 963{
 964	long mtype;
 965
 966	if (get_user(mtype, &msgp->mtype))
 967		return -EFAULT;
 968	return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);
 969}
 970
 971SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
 972		int, msgflg)
 973{
 974	return ksys_msgsnd(msqid, msgp, msgsz, msgflg);
 975}
 976
 977#ifdef CONFIG_COMPAT
 978
 979struct compat_msgbuf {
 980	compat_long_t mtype;
 981	char mtext[1];
 982};
 983
 984long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,
 985		       compat_ssize_t msgsz, int msgflg)
 986{
 987	struct compat_msgbuf __user *up = compat_ptr(msgp);
 988	compat_long_t mtype;
 989
 990	if (get_user(mtype, &up->mtype))
 991		return -EFAULT;
 992	return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);
 993}
 994
 995COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,
 996		       compat_ssize_t, msgsz, int, msgflg)
 997{
 998	return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);
 999}
1000#endif
1001
1002static inline int convert_mode(long *msgtyp, int msgflg)
1003{
1004	if (msgflg & MSG_COPY)
1005		return SEARCH_NUMBER;
1006	/*
1007	 *  find message of correct type.
1008	 *  msgtyp = 0 => get first.
1009	 *  msgtyp > 0 => get first message of matching type.
1010	 *  msgtyp < 0 => get message with least type must be < abs(msgtype).
1011	 */
1012	if (*msgtyp == 0)
1013		return SEARCH_ANY;
1014	if (*msgtyp < 0) {
1015		if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
1016			*msgtyp = LONG_MAX;
1017		else
1018			*msgtyp = -*msgtyp;
1019		return SEARCH_LESSEQUAL;
1020	}
1021	if (msgflg & MSG_EXCEPT)
1022		return SEARCH_NOTEQUAL;
1023	return SEARCH_EQUAL;
1024}
1025
1026static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1027{
1028	struct msgbuf __user *msgp = dest;
1029	size_t msgsz;
1030
1031	if (put_user(msg->m_type, &msgp->mtype))
1032		return -EFAULT;
1033
1034	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1035	if (store_msg(msgp->mtext, msg, msgsz))
1036		return -EFAULT;
1037	return msgsz;
1038}
1039
1040#ifdef CONFIG_CHECKPOINT_RESTORE
1041/*
1042 * This function creates new kernel message structure, large enough to store
1043 * bufsz message bytes.
1044 */
1045static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1046{
1047	struct msg_msg *copy;
1048
1049	/*
1050	 * Create dummy message to copy real message to.
1051	 */
1052	copy = load_msg(buf, bufsz);
1053	if (!IS_ERR(copy))
1054		copy->m_ts = bufsz;
1055	return copy;
1056}
1057
1058static inline void free_copy(struct msg_msg *copy)
1059{
1060	if (copy)
1061		free_msg(copy);
1062}
1063#else
1064static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
1065{
1066	return ERR_PTR(-ENOSYS);
1067}
1068
1069static inline void free_copy(struct msg_msg *copy)
1070{
1071}
1072#endif
1073
1074static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
1075{
1076	struct msg_msg *msg, *found = NULL;
1077	long count = 0;
1078
1079	list_for_each_entry(msg, &msq->q_messages, m_list) {
1080		if (testmsg(msg, *msgtyp, mode) &&
1081		    !security_msg_queue_msgrcv(&msq->q_perm, msg, current,
1082					       *msgtyp, mode)) {
1083			if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) {
1084				*msgtyp = msg->m_type - 1;
1085				found = msg;
1086			} else if (mode == SEARCH_NUMBER) {
1087				if (*msgtyp == count)
1088					return msg;
1089			} else
1090				return msg;
1091			count++;
1092		}
1093	}
1094
1095	return found ?: ERR_PTR(-EAGAIN);
1096}
1097
1098static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
1099	       long (*msg_handler)(void __user *, struct msg_msg *, size_t))
1100{
 
 
1101	int mode;
1102	struct msg_queue *msq;
1103	struct ipc_namespace *ns;
1104	struct msg_msg *msg, *copy = NULL;
1105	DEFINE_WAKE_Q(wake_q);
1106
1107	ns = current->nsproxy->ipc_ns;
1108
1109	if (msqid < 0 || (long) bufsz < 0)
1110		return -EINVAL;
1111
1112	if (msgflg & MSG_COPY) {
1113		if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT))
1114			return -EINVAL;
1115		copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax));
1116		if (IS_ERR(copy))
1117			return PTR_ERR(copy);
1118	}
1119	mode = convert_mode(&msgtyp, msgflg);
 
1120
1121	rcu_read_lock();
1122	msq = msq_obtain_object_check(ns, msqid);
1123	if (IS_ERR(msq)) {
1124		rcu_read_unlock();
1125		free_copy(copy);
1126		return PTR_ERR(msq);
1127	}
1128
1129	for (;;) {
1130		struct msg_receiver msr_d;
 
1131
1132		msg = ERR_PTR(-EACCES);
1133		if (ipcperms(ns, &msq->q_perm, S_IRUGO))
1134			goto out_unlock1;
1135
1136		ipc_lock_object(&msq->q_perm);
1137
1138		/* raced with RMID? */
1139		if (!ipc_valid_object(&msq->q_perm)) {
1140			msg = ERR_PTR(-EIDRM);
1141			goto out_unlock0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1142		}
1143
1144		msg = find_msg(msq, &msgtyp, mode);
1145		if (!IS_ERR(msg)) {
1146			/*
1147			 * Found a suitable message.
1148			 * Unlink it from the queue.
1149			 */
1150			if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
1151				msg = ERR_PTR(-E2BIG);
1152				goto out_unlock0;
1153			}
1154			/*
1155			 * If we are copying, then do not unlink message and do
1156			 * not update queue parameters.
1157			 */
1158			if (msgflg & MSG_COPY) {
1159				msg = copy_msg(msg, copy);
1160				goto out_unlock0;
1161			}
1162
1163			list_del(&msg->m_list);
1164			msq->q_qnum--;
1165			msq->q_rtime = ktime_get_real_seconds();
1166			ipc_update_pid(&msq->q_lrpid, task_tgid(current));
1167			msq->q_cbytes -= msg->m_ts;
1168			percpu_counter_sub_local(&ns->percpu_msg_bytes, msg->m_ts);
1169			percpu_counter_sub_local(&ns->percpu_msg_hdrs, 1);
1170			ss_wakeup(msq, &wake_q, false);
1171
1172			goto out_unlock0;
1173		}
1174
1175		/* No message waiting. Wait for a message */
1176		if (msgflg & IPC_NOWAIT) {
1177			msg = ERR_PTR(-ENOMSG);
1178			goto out_unlock0;
1179		}
1180
1181		list_add_tail(&msr_d.r_list, &msq->q_receivers);
1182		msr_d.r_tsk = current;
1183		msr_d.r_msgtype = msgtyp;
1184		msr_d.r_mode = mode;
1185		if (msgflg & MSG_NOERROR)
1186			msr_d.r_maxsize = INT_MAX;
1187		else
1188			msr_d.r_maxsize = bufsz;
 
 
 
1189
1190		/* memory barrier not require due to ipc_lock_object() */
1191		WRITE_ONCE(msr_d.r_msg, ERR_PTR(-EAGAIN));
1192
1193		/* memory barrier not required, we own ipc_lock_object() */
1194		__set_current_state(TASK_INTERRUPTIBLE);
1195
1196		ipc_unlock_object(&msq->q_perm);
1197		rcu_read_unlock();
1198		schedule();
1199
1200		/*
1201		 * Lockless receive, part 1:
1202		 * We don't hold a reference to the queue and getting a
1203		 * reference would defeat the idea of a lockless operation,
1204		 * thus the code relies on rcu to guarantee the existence of
1205		 * msq:
1206		 * Prior to destruction, expunge_all(-EIRDM) changes r_msg.
1207		 * Thus if r_msg is -EAGAIN, then the queue not yet destroyed.
 
 
1208		 */
1209		rcu_read_lock();
1210
1211		/*
1212		 * Lockless receive, part 2:
1213		 * The work in pipelined_send() and expunge_all():
1214		 * - Set pointer to message
1215		 * - Queue the receiver task for later wakeup
1216		 * - Wake up the process after the lock is dropped.
1217		 *
1218		 * Should the process wake up before this wakeup (due to a
1219		 * signal) it will either see the message and continue ...
 
 
 
 
 
1220		 */
1221		msg = READ_ONCE(msr_d.r_msg);
1222		if (msg != ERR_PTR(-EAGAIN)) {
1223			/* see MSG_BARRIER for purpose/pairing */
1224			smp_acquire__after_ctrl_dep();
1225
1226			goto out_unlock1;
1227		}
1228
1229		 /*
1230		  * ... or see -EAGAIN, acquire the lock to check the message
1231		  * again.
1232		  */
1233		ipc_lock_object(&msq->q_perm);
1234
1235		msg = READ_ONCE(msr_d.r_msg);
 
 
 
1236		if (msg != ERR_PTR(-EAGAIN))
1237			goto out_unlock0;
1238
1239		list_del(&msr_d.r_list);
1240		if (signal_pending(current)) {
1241			msg = ERR_PTR(-ERESTARTNOHAND);
1242			goto out_unlock0;
 
 
1243		}
1244
1245		ipc_unlock_object(&msq->q_perm);
1246	}
 
 
1247
1248out_unlock0:
1249	ipc_unlock_object(&msq->q_perm);
1250	wake_up_q(&wake_q);
1251out_unlock1:
1252	rcu_read_unlock();
1253	if (IS_ERR(msg)) {
1254		free_copy(copy);
1255		return PTR_ERR(msg);
1256	}
1257
1258	bufsz = msg_handler(buf, msg, bufsz);
1259	free_msg(msg);
1260
1261	return bufsz;
1262}
1263
1264long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
1265		 long msgtyp, int msgflg)
1266{
1267	return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
1268}
1269
1270SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
1271		long, msgtyp, int, msgflg)
1272{
1273	return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1274}
1275
1276#ifdef CONFIG_COMPAT
1277static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
1278{
1279	struct compat_msgbuf __user *msgp = dest;
1280	size_t msgsz;
1281
1282	if (put_user(msg->m_type, &msgp->mtype))
1283		return -EFAULT;
1284
1285	msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
1286	if (store_msg(msgp->mtext, msg, msgsz))
1287		return -EFAULT;
1288	return msgsz;
1289}
1290
1291long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
1292			compat_long_t msgtyp, int msgflg)
1293{
1294	return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
1295			 msgflg, compat_do_msg_fill);
1296}
1297
1298COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
1299		       compat_ssize_t, msgsz, compat_long_t, msgtyp,
1300		       int, msgflg)
1301{
1302	return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
1303}
1304#endif
1305
1306int msg_init_ns(struct ipc_namespace *ns)
1307{
1308	int ret;
1309
1310	ns->msg_ctlmax = MSGMAX;
1311	ns->msg_ctlmnb = MSGMNB;
1312	ns->msg_ctlmni = MSGMNI;
1313
1314	ret = percpu_counter_init(&ns->percpu_msg_bytes, 0, GFP_KERNEL);
1315	if (ret)
1316		goto fail_msg_bytes;
1317	ret = percpu_counter_init(&ns->percpu_msg_hdrs, 0, GFP_KERNEL);
1318	if (ret)
1319		goto fail_msg_hdrs;
1320	ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
1321	return 0;
1322
1323fail_msg_hdrs:
1324	percpu_counter_destroy(&ns->percpu_msg_bytes);
1325fail_msg_bytes:
1326	return ret;
1327}
1328
1329#ifdef CONFIG_IPC_NS
1330void msg_exit_ns(struct ipc_namespace *ns)
1331{
1332	free_ipcs(ns, &msg_ids(ns), freeque);
1333	idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
1334	rhashtable_destroy(&ns->ids[IPC_MSG_IDS].key_ht);
1335	percpu_counter_destroy(&ns->percpu_msg_bytes);
1336	percpu_counter_destroy(&ns->percpu_msg_hdrs);
1337}
1338#endif
1339
1340#ifdef CONFIG_PROC_FS
1341static int sysvipc_msg_proc_show(struct seq_file *s, void *it)
1342{
1343	struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1344	struct user_namespace *user_ns = seq_user_ns(s);
1345	struct kern_ipc_perm *ipcp = it;
1346	struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
1347
1348	seq_printf(s,
1349		   "%10d %10d  %4o  %10lu %10lu %5u %5u %5u %5u %5u %5u %10llu %10llu %10llu\n",
1350		   msq->q_perm.key,
1351		   msq->q_perm.id,
1352		   msq->q_perm.mode,
1353		   msq->q_cbytes,
1354		   msq->q_qnum,
1355		   pid_nr_ns(msq->q_lspid, pid_ns),
1356		   pid_nr_ns(msq->q_lrpid, pid_ns),
1357		   from_kuid_munged(user_ns, msq->q_perm.uid),
1358		   from_kgid_munged(user_ns, msq->q_perm.gid),
1359		   from_kuid_munged(user_ns, msq->q_perm.cuid),
1360		   from_kgid_munged(user_ns, msq->q_perm.cgid),
1361		   msq->q_stime,
1362		   msq->q_rtime,
1363		   msq->q_ctime);
1364
1365	return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1366}
1367#endif
1368
1369void __init msg_init(void)
1370{
1371	msg_init_ns(&init_ipc_ns);
1372
1373	ipc_init_proc_interface("sysvipc/msg",
1374				"       key      msqid perms      cbytes       qnum lspid lrpid   uid   gid  cuid  cgid      stime      rtime      ctime\n",
1375				IPC_MSG_IDS, sysvipc_msg_proc_show);
1376}