projects/linux·blob v5.7-rc2 · refs

1352 lines · 31.6 KiB

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