blob: ff10d43b51848e70eccedf3bd6a6db22bc2e9837
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 <linux/uaccess.h> |
43 | #include "util.h" |
44 | |
45 | /* one msg_receiver structure for each sleeping receiver */ |
46 | struct msg_receiver { |
47 | struct list_head r_list; |
48 | struct task_struct *r_tsk; |
49 | |
50 | int r_mode; |
51 | long r_msgtype; |
52 | long r_maxsize; |
53 | |
54 | struct msg_msg *r_msg; |
55 | }; |
56 | |
57 | /* one msg_sender for each sleeping sender */ |
58 | struct msg_sender { |
59 | struct list_head list; |
60 | struct task_struct *tsk; |
61 | size_t msgsz; |
62 | }; |
63 | |
64 | #define SEARCH_ANY 1 |
65 | #define SEARCH_EQUAL 2 |
66 | #define SEARCH_NOTEQUAL 3 |
67 | #define SEARCH_LESSEQUAL 4 |
68 | #define SEARCH_NUMBER 5 |
69 | |
70 | #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS]) |
71 | |
72 | static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id) |
73 | { |
74 | struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id); |
75 | |
76 | if (IS_ERR(ipcp)) |
77 | return ERR_CAST(ipcp); |
78 | |
79 | return container_of(ipcp, struct msg_queue, q_perm); |
80 | } |
81 | |
82 | static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns, |
83 | int id) |
84 | { |
85 | struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id); |
86 | |
87 | if (IS_ERR(ipcp)) |
88 | return ERR_CAST(ipcp); |
89 | |
90 | return container_of(ipcp, struct msg_queue, q_perm); |
91 | } |
92 | |
93 | static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) |
94 | { |
95 | ipc_rmid(&msg_ids(ns), &s->q_perm); |
96 | } |
97 | |
98 | static void msg_rcu_free(struct rcu_head *head) |
99 | { |
100 | struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); |
101 | struct msg_queue *msq = ipc_rcu_to_struct(p); |
102 | |
103 | security_msg_queue_free(msq); |
104 | ipc_rcu_free(head); |
105 | } |
106 | |
107 | /** |
108 | * newque - Create a new msg queue |
109 | * @ns: namespace |
110 | * @params: ptr to the structure that contains the key and msgflg |
111 | * |
112 | * Called with msg_ids.rwsem held (writer) |
113 | */ |
114 | static int newque(struct ipc_namespace *ns, struct ipc_params *params) |
115 | { |
116 | struct msg_queue *msq; |
117 | int id, retval; |
118 | key_t key = params->key; |
119 | int msgflg = params->flg; |
120 | |
121 | msq = ipc_rcu_alloc(sizeof(*msq)); |
122 | if (!msq) |
123 | return -ENOMEM; |
124 | |
125 | msq->q_perm.mode = msgflg & S_IRWXUGO; |
126 | msq->q_perm.key = key; |
127 | |
128 | msq->q_perm.security = NULL; |
129 | retval = security_msg_queue_alloc(msq); |
130 | if (retval) { |
131 | ipc_rcu_putref(msq, ipc_rcu_free); |
132 | return retval; |
133 | } |
134 | |
135 | msq->q_stime = msq->q_rtime = 0; |
136 | msq->q_ctime = get_seconds(); |
137 | msq->q_cbytes = msq->q_qnum = 0; |
138 | msq->q_qbytes = ns->msg_ctlmnb; |
139 | msq->q_lspid = msq->q_lrpid = 0; |
140 | INIT_LIST_HEAD(&msq->q_messages); |
141 | INIT_LIST_HEAD(&msq->q_receivers); |
142 | INIT_LIST_HEAD(&msq->q_senders); |
143 | |
144 | /* ipc_addid() locks msq upon success. */ |
145 | id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); |
146 | if (id < 0) { |
147 | ipc_rcu_putref(msq, msg_rcu_free); |
148 | return id; |
149 | } |
150 | |
151 | ipc_unlock_object(&msq->q_perm); |
152 | rcu_read_unlock(); |
153 | |
154 | return msq->q_perm.id; |
155 | } |
156 | |
157 | static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz) |
158 | { |
159 | return msgsz + msq->q_cbytes <= msq->q_qbytes && |
160 | 1 + msq->q_qnum <= msq->q_qbytes; |
161 | } |
162 | |
163 | static inline void ss_add(struct msg_queue *msq, |
164 | struct msg_sender *mss, size_t msgsz) |
165 | { |
166 | mss->tsk = current; |
167 | mss->msgsz = msgsz; |
168 | __set_current_state(TASK_INTERRUPTIBLE); |
169 | list_add_tail(&mss->list, &msq->q_senders); |
170 | } |
171 | |
172 | static inline void ss_del(struct msg_sender *mss) |
173 | { |
174 | if (mss->list.next) |
175 | list_del(&mss->list); |
176 | } |
177 | |
178 | static void ss_wakeup(struct msg_queue *msq, |
179 | struct wake_q_head *wake_q, bool kill) |
180 | { |
181 | struct msg_sender *mss, *t; |
182 | struct task_struct *stop_tsk = NULL; |
183 | struct list_head *h = &msq->q_senders; |
184 | |
185 | list_for_each_entry_safe(mss, t, h, list) { |
186 | if (kill) |
187 | mss->list.next = NULL; |
188 | |
189 | /* |
190 | * Stop at the first task we don't wakeup, |
191 | * we've already iterated the original |
192 | * sender queue. |
193 | */ |
194 | else if (stop_tsk == mss->tsk) |
195 | break; |
196 | /* |
197 | * We are not in an EIDRM scenario here, therefore |
198 | * verify that we really need to wakeup the task. |
199 | * To maintain current semantics and wakeup order, |
200 | * move the sender to the tail on behalf of the |
201 | * blocked task. |
202 | */ |
203 | else if (!msg_fits_inqueue(msq, mss->msgsz)) { |
204 | if (!stop_tsk) |
205 | stop_tsk = mss->tsk; |
206 | |
207 | list_move_tail(&mss->list, &msq->q_senders); |
208 | continue; |
209 | } |
210 | |
211 | wake_q_add(wake_q, mss->tsk); |
212 | } |
213 | } |
214 | |
215 | static void expunge_all(struct msg_queue *msq, int res, |
216 | struct wake_q_head *wake_q) |
217 | { |
218 | struct msg_receiver *msr, *t; |
219 | |
220 | list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { |
221 | wake_q_add(wake_q, msr->r_tsk); |
222 | WRITE_ONCE(msr->r_msg, ERR_PTR(res)); |
223 | } |
224 | } |
225 | |
226 | /* |
227 | * freeque() wakes up waiters on the sender and receiver waiting queue, |
228 | * removes the message queue from message queue ID IDR, and cleans up all the |
229 | * messages associated with this queue. |
230 | * |
231 | * msg_ids.rwsem (writer) and the spinlock for this message queue are held |
232 | * before freeque() is called. msg_ids.rwsem remains locked on exit. |
233 | */ |
234 | static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
235 | { |
236 | struct msg_msg *msg, *t; |
237 | struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); |
238 | WAKE_Q(wake_q); |
239 | |
240 | expunge_all(msq, -EIDRM, &wake_q); |
241 | ss_wakeup(msq, &wake_q, true); |
242 | msg_rmid(ns, msq); |
243 | ipc_unlock_object(&msq->q_perm); |
244 | wake_up_q(&wake_q); |
245 | rcu_read_unlock(); |
246 | |
247 | list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) { |
248 | atomic_dec(&ns->msg_hdrs); |
249 | free_msg(msg); |
250 | } |
251 | atomic_sub(msq->q_cbytes, &ns->msg_bytes); |
252 | ipc_rcu_putref(msq, msg_rcu_free); |
253 | } |
254 | |
255 | /* |
256 | * Called with msg_ids.rwsem and ipcp locked. |
257 | */ |
258 | static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg) |
259 | { |
260 | struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); |
261 | |
262 | return security_msg_queue_associate(msq, msgflg); |
263 | } |
264 | |
265 | SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) |
266 | { |
267 | struct ipc_namespace *ns; |
268 | static const struct ipc_ops msg_ops = { |
269 | .getnew = newque, |
270 | .associate = msg_security, |
271 | }; |
272 | struct ipc_params msg_params; |
273 | |
274 | ns = current->nsproxy->ipc_ns; |
275 | |
276 | msg_params.key = key; |
277 | msg_params.flg = msgflg; |
278 | |
279 | return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params); |
280 | } |
281 | |
282 | static inline unsigned long |
283 | copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) |
284 | { |
285 | switch (version) { |
286 | case IPC_64: |
287 | return copy_to_user(buf, in, sizeof(*in)); |
288 | case IPC_OLD: |
289 | { |
290 | struct msqid_ds out; |
291 | |
292 | memset(&out, 0, sizeof(out)); |
293 | |
294 | ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); |
295 | |
296 | out.msg_stime = in->msg_stime; |
297 | out.msg_rtime = in->msg_rtime; |
298 | out.msg_ctime = in->msg_ctime; |
299 | |
300 | if (in->msg_cbytes > USHRT_MAX) |
301 | out.msg_cbytes = USHRT_MAX; |
302 | else |
303 | out.msg_cbytes = in->msg_cbytes; |
304 | out.msg_lcbytes = in->msg_cbytes; |
305 | |
306 | if (in->msg_qnum > USHRT_MAX) |
307 | out.msg_qnum = USHRT_MAX; |
308 | else |
309 | out.msg_qnum = in->msg_qnum; |
310 | |
311 | if (in->msg_qbytes > USHRT_MAX) |
312 | out.msg_qbytes = USHRT_MAX; |
313 | else |
314 | out.msg_qbytes = in->msg_qbytes; |
315 | out.msg_lqbytes = in->msg_qbytes; |
316 | |
317 | out.msg_lspid = in->msg_lspid; |
318 | out.msg_lrpid = in->msg_lrpid; |
319 | |
320 | return copy_to_user(buf, &out, sizeof(out)); |
321 | } |
322 | default: |
323 | return -EINVAL; |
324 | } |
325 | } |
326 | |
327 | static inline unsigned long |
328 | copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) |
329 | { |
330 | switch (version) { |
331 | case IPC_64: |
332 | if (copy_from_user(out, buf, sizeof(*out))) |
333 | return -EFAULT; |
334 | return 0; |
335 | case IPC_OLD: |
336 | { |
337 | struct msqid_ds tbuf_old; |
338 | |
339 | if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) |
340 | return -EFAULT; |
341 | |
342 | out->msg_perm.uid = tbuf_old.msg_perm.uid; |
343 | out->msg_perm.gid = tbuf_old.msg_perm.gid; |
344 | out->msg_perm.mode = tbuf_old.msg_perm.mode; |
345 | |
346 | if (tbuf_old.msg_qbytes == 0) |
347 | out->msg_qbytes = tbuf_old.msg_lqbytes; |
348 | else |
349 | out->msg_qbytes = tbuf_old.msg_qbytes; |
350 | |
351 | return 0; |
352 | } |
353 | default: |
354 | return -EINVAL; |
355 | } |
356 | } |
357 | |
358 | /* |
359 | * This function handles some msgctl commands which require the rwsem |
360 | * to be held in write mode. |
361 | * NOTE: no locks must be held, the rwsem is taken inside this function. |
362 | */ |
363 | static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, |
364 | struct msqid_ds __user *buf, int version) |
365 | { |
366 | struct kern_ipc_perm *ipcp; |
367 | struct msqid64_ds uninitialized_var(msqid64); |
368 | struct msg_queue *msq; |
369 | int err; |
370 | |
371 | if (cmd == IPC_SET) { |
372 | if (copy_msqid_from_user(&msqid64, buf, version)) |
373 | return -EFAULT; |
374 | } |
375 | |
376 | down_write(&msg_ids(ns).rwsem); |
377 | rcu_read_lock(); |
378 | |
379 | ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd, |
380 | &msqid64.msg_perm, msqid64.msg_qbytes); |
381 | if (IS_ERR(ipcp)) { |
382 | err = PTR_ERR(ipcp); |
383 | goto out_unlock1; |
384 | } |
385 | |
386 | msq = container_of(ipcp, struct msg_queue, q_perm); |
387 | |
388 | err = security_msg_queue_msgctl(msq, cmd); |
389 | if (err) |
390 | goto out_unlock1; |
391 | |
392 | switch (cmd) { |
393 | case IPC_RMID: |
394 | ipc_lock_object(&msq->q_perm); |
395 | /* freeque unlocks the ipc object and rcu */ |
396 | freeque(ns, ipcp); |
397 | goto out_up; |
398 | case IPC_SET: |
399 | { |
400 | WAKE_Q(wake_q); |
401 | |
402 | if (msqid64.msg_qbytes > ns->msg_ctlmnb && |
403 | !capable(CAP_SYS_RESOURCE)) { |
404 | err = -EPERM; |
405 | goto out_unlock1; |
406 | } |
407 | |
408 | ipc_lock_object(&msq->q_perm); |
409 | err = ipc_update_perm(&msqid64.msg_perm, ipcp); |
410 | if (err) |
411 | goto out_unlock0; |
412 | |
413 | msq->q_qbytes = msqid64.msg_qbytes; |
414 | |
415 | msq->q_ctime = get_seconds(); |
416 | /* |
417 | * Sleeping receivers might be excluded by |
418 | * stricter permissions. |
419 | */ |
420 | expunge_all(msq, -EAGAIN, &wake_q); |
421 | /* |
422 | * Sleeping senders might be able to send |
423 | * due to a larger queue size. |
424 | */ |
425 | ss_wakeup(msq, &wake_q, false); |
426 | ipc_unlock_object(&msq->q_perm); |
427 | wake_up_q(&wake_q); |
428 | |
429 | goto out_unlock1; |
430 | } |
431 | default: |
432 | err = -EINVAL; |
433 | goto out_unlock1; |
434 | } |
435 | |
436 | out_unlock0: |
437 | ipc_unlock_object(&msq->q_perm); |
438 | out_unlock1: |
439 | rcu_read_unlock(); |
440 | out_up: |
441 | up_write(&msg_ids(ns).rwsem); |
442 | return err; |
443 | } |
444 | |
445 | static int msgctl_nolock(struct ipc_namespace *ns, int msqid, |
446 | int cmd, int version, void __user *buf) |
447 | { |
448 | int err; |
449 | struct msg_queue *msq; |
450 | |
451 | switch (cmd) { |
452 | case IPC_INFO: |
453 | case MSG_INFO: |
454 | { |
455 | struct msginfo msginfo; |
456 | int max_id; |
457 | |
458 | if (!buf) |
459 | return -EFAULT; |
460 | |
461 | /* |
462 | * We must not return kernel stack data. |
463 | * due to padding, it's not enough |
464 | * to set all member fields. |
465 | */ |
466 | err = security_msg_queue_msgctl(NULL, cmd); |
467 | if (err) |
468 | return err; |
469 | |
470 | memset(&msginfo, 0, sizeof(msginfo)); |
471 | msginfo.msgmni = ns->msg_ctlmni; |
472 | msginfo.msgmax = ns->msg_ctlmax; |
473 | msginfo.msgmnb = ns->msg_ctlmnb; |
474 | msginfo.msgssz = MSGSSZ; |
475 | msginfo.msgseg = MSGSEG; |
476 | down_read(&msg_ids(ns).rwsem); |
477 | if (cmd == MSG_INFO) { |
478 | msginfo.msgpool = msg_ids(ns).in_use; |
479 | msginfo.msgmap = atomic_read(&ns->msg_hdrs); |
480 | msginfo.msgtql = atomic_read(&ns->msg_bytes); |
481 | } else { |
482 | msginfo.msgmap = MSGMAP; |
483 | msginfo.msgpool = MSGPOOL; |
484 | msginfo.msgtql = MSGTQL; |
485 | } |
486 | max_id = ipc_get_maxid(&msg_ids(ns)); |
487 | up_read(&msg_ids(ns).rwsem); |
488 | if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) |
489 | return -EFAULT; |
490 | return (max_id < 0) ? 0 : max_id; |
491 | } |
492 | |
493 | case MSG_STAT: |
494 | case IPC_STAT: |
495 | { |
496 | struct msqid64_ds tbuf; |
497 | int success_return; |
498 | |
499 | if (!buf) |
500 | return -EFAULT; |
501 | |
502 | memset(&tbuf, 0, sizeof(tbuf)); |
503 | |
504 | rcu_read_lock(); |
505 | if (cmd == MSG_STAT) { |
506 | msq = msq_obtain_object(ns, msqid); |
507 | if (IS_ERR(msq)) { |
508 | err = PTR_ERR(msq); |
509 | goto out_unlock; |
510 | } |
511 | success_return = msq->q_perm.id; |
512 | } else { |
513 | msq = msq_obtain_object_check(ns, msqid); |
514 | if (IS_ERR(msq)) { |
515 | err = PTR_ERR(msq); |
516 | goto out_unlock; |
517 | } |
518 | success_return = 0; |
519 | } |
520 | |
521 | err = -EACCES; |
522 | if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
523 | goto out_unlock; |
524 | |
525 | err = security_msg_queue_msgctl(msq, cmd); |
526 | if (err) |
527 | goto out_unlock; |
528 | |
529 | kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); |
530 | tbuf.msg_stime = msq->q_stime; |
531 | tbuf.msg_rtime = msq->q_rtime; |
532 | tbuf.msg_ctime = msq->q_ctime; |
533 | tbuf.msg_cbytes = msq->q_cbytes; |
534 | tbuf.msg_qnum = msq->q_qnum; |
535 | tbuf.msg_qbytes = msq->q_qbytes; |
536 | tbuf.msg_lspid = msq->q_lspid; |
537 | tbuf.msg_lrpid = msq->q_lrpid; |
538 | rcu_read_unlock(); |
539 | |
540 | if (copy_msqid_to_user(buf, &tbuf, version)) |
541 | return -EFAULT; |
542 | return success_return; |
543 | } |
544 | |
545 | default: |
546 | return -EINVAL; |
547 | } |
548 | |
549 | return err; |
550 | out_unlock: |
551 | rcu_read_unlock(); |
552 | return err; |
553 | } |
554 | |
555 | SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) |
556 | { |
557 | int version; |
558 | struct ipc_namespace *ns; |
559 | |
560 | if (msqid < 0 || cmd < 0) |
561 | return -EINVAL; |
562 | |
563 | version = ipc_parse_version(&cmd); |
564 | ns = current->nsproxy->ipc_ns; |
565 | |
566 | switch (cmd) { |
567 | case IPC_INFO: |
568 | case MSG_INFO: |
569 | case MSG_STAT: /* msqid is an index rather than a msg queue id */ |
570 | case IPC_STAT: |
571 | return msgctl_nolock(ns, msqid, cmd, version, buf); |
572 | case IPC_SET: |
573 | case IPC_RMID: |
574 | return msgctl_down(ns, msqid, cmd, buf, version); |
575 | default: |
576 | return -EINVAL; |
577 | } |
578 | } |
579 | |
580 | static int testmsg(struct msg_msg *msg, long type, int mode) |
581 | { |
582 | switch (mode) { |
583 | case SEARCH_ANY: |
584 | case SEARCH_NUMBER: |
585 | return 1; |
586 | case SEARCH_LESSEQUAL: |
587 | if (msg->m_type <= type) |
588 | return 1; |
589 | break; |
590 | case SEARCH_EQUAL: |
591 | if (msg->m_type == type) |
592 | return 1; |
593 | break; |
594 | case SEARCH_NOTEQUAL: |
595 | if (msg->m_type != type) |
596 | return 1; |
597 | break; |
598 | } |
599 | return 0; |
600 | } |
601 | |
602 | static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg, |
603 | struct wake_q_head *wake_q) |
604 | { |
605 | struct msg_receiver *msr, *t; |
606 | |
607 | list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { |
608 | if (testmsg(msg, msr->r_msgtype, msr->r_mode) && |
609 | !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, |
610 | msr->r_msgtype, msr->r_mode)) { |
611 | |
612 | list_del(&msr->r_list); |
613 | if (msr->r_maxsize < msg->m_ts) { |
614 | wake_q_add(wake_q, msr->r_tsk); |
615 | WRITE_ONCE(msr->r_msg, ERR_PTR(-E2BIG)); |
616 | } else { |
617 | msq->q_lrpid = task_pid_vnr(msr->r_tsk); |
618 | msq->q_rtime = get_seconds(); |
619 | |
620 | wake_q_add(wake_q, msr->r_tsk); |
621 | WRITE_ONCE(msr->r_msg, msg); |
622 | return 1; |
623 | } |
624 | } |
625 | } |
626 | |
627 | return 0; |
628 | } |
629 | |
630 | long do_msgsnd(int msqid, long mtype, void __user *mtext, |
631 | size_t msgsz, int msgflg) |
632 | { |
633 | struct msg_queue *msq; |
634 | struct msg_msg *msg; |
635 | int err; |
636 | struct ipc_namespace *ns; |
637 | WAKE_Q(wake_q); |
638 | |
639 | ns = current->nsproxy->ipc_ns; |
640 | |
641 | if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) |
642 | return -EINVAL; |
643 | if (mtype < 1) |
644 | return -EINVAL; |
645 | |
646 | msg = load_msg(mtext, msgsz); |
647 | if (IS_ERR(msg)) |
648 | return PTR_ERR(msg); |
649 | |
650 | msg->m_type = mtype; |
651 | msg->m_ts = msgsz; |
652 | |
653 | rcu_read_lock(); |
654 | msq = msq_obtain_object_check(ns, msqid); |
655 | if (IS_ERR(msq)) { |
656 | err = PTR_ERR(msq); |
657 | goto out_unlock1; |
658 | } |
659 | |
660 | ipc_lock_object(&msq->q_perm); |
661 | |
662 | for (;;) { |
663 | struct msg_sender s; |
664 | |
665 | err = -EACCES; |
666 | if (ipcperms(ns, &msq->q_perm, S_IWUGO)) |
667 | goto out_unlock0; |
668 | |
669 | /* raced with RMID? */ |
670 | if (!ipc_valid_object(&msq->q_perm)) { |
671 | err = -EIDRM; |
672 | goto out_unlock0; |
673 | } |
674 | |
675 | err = security_msg_queue_msgsnd(msq, msg, msgflg); |
676 | if (err) |
677 | goto out_unlock0; |
678 | |
679 | if (msg_fits_inqueue(msq, msgsz)) |
680 | break; |
681 | |
682 | /* queue full, wait: */ |
683 | if (msgflg & IPC_NOWAIT) { |
684 | err = -EAGAIN; |
685 | goto out_unlock0; |
686 | } |
687 | |
688 | /* enqueue the sender and prepare to block */ |
689 | ss_add(msq, &s, msgsz); |
690 | |
691 | if (!ipc_rcu_getref(msq)) { |
692 | err = -EIDRM; |
693 | goto out_unlock0; |
694 | } |
695 | |
696 | ipc_unlock_object(&msq->q_perm); |
697 | rcu_read_unlock(); |
698 | schedule(); |
699 | |
700 | rcu_read_lock(); |
701 | ipc_lock_object(&msq->q_perm); |
702 | |
703 | ipc_rcu_putref(msq, msg_rcu_free); |
704 | /* raced with RMID? */ |
705 | if (!ipc_valid_object(&msq->q_perm)) { |
706 | err = -EIDRM; |
707 | goto out_unlock0; |
708 | } |
709 | ss_del(&s); |
710 | |
711 | if (signal_pending(current)) { |
712 | err = -ERESTARTNOHAND; |
713 | goto out_unlock0; |
714 | } |
715 | |
716 | } |
717 | |
718 | msq->q_lspid = task_tgid_vnr(current); |
719 | msq->q_stime = get_seconds(); |
720 | |
721 | if (!pipelined_send(msq, msg, &wake_q)) { |
722 | /* no one is waiting for this message, enqueue it */ |
723 | list_add_tail(&msg->m_list, &msq->q_messages); |
724 | msq->q_cbytes += msgsz; |
725 | msq->q_qnum++; |
726 | atomic_add(msgsz, &ns->msg_bytes); |
727 | atomic_inc(&ns->msg_hdrs); |
728 | } |
729 | |
730 | err = 0; |
731 | msg = NULL; |
732 | |
733 | out_unlock0: |
734 | ipc_unlock_object(&msq->q_perm); |
735 | wake_up_q(&wake_q); |
736 | out_unlock1: |
737 | rcu_read_unlock(); |
738 | if (msg != NULL) |
739 | free_msg(msg); |
740 | return err; |
741 | } |
742 | |
743 | SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
744 | int, msgflg) |
745 | { |
746 | long mtype; |
747 | |
748 | if (get_user(mtype, &msgp->mtype)) |
749 | return -EFAULT; |
750 | return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); |
751 | } |
752 | |
753 | static inline int convert_mode(long *msgtyp, int msgflg) |
754 | { |
755 | if (msgflg & MSG_COPY) |
756 | return SEARCH_NUMBER; |
757 | /* |
758 | * find message of correct type. |
759 | * msgtyp = 0 => get first. |
760 | * msgtyp > 0 => get first message of matching type. |
761 | * msgtyp < 0 => get message with least type must be < abs(msgtype). |
762 | */ |
763 | if (*msgtyp == 0) |
764 | return SEARCH_ANY; |
765 | if (*msgtyp < 0) { |
766 | if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */ |
767 | *msgtyp = LONG_MAX; |
768 | else |
769 | *msgtyp = -*msgtyp; |
770 | return SEARCH_LESSEQUAL; |
771 | } |
772 | if (msgflg & MSG_EXCEPT) |
773 | return SEARCH_NOTEQUAL; |
774 | return SEARCH_EQUAL; |
775 | } |
776 | |
777 | static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) |
778 | { |
779 | struct msgbuf __user *msgp = dest; |
780 | size_t msgsz; |
781 | |
782 | if (put_user(msg->m_type, &msgp->mtype)) |
783 | return -EFAULT; |
784 | |
785 | msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; |
786 | if (store_msg(msgp->mtext, msg, msgsz)) |
787 | return -EFAULT; |
788 | return msgsz; |
789 | } |
790 | |
791 | #ifdef CONFIG_CHECKPOINT_RESTORE |
792 | /* |
793 | * This function creates new kernel message structure, large enough to store |
794 | * bufsz message bytes. |
795 | */ |
796 | static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) |
797 | { |
798 | struct msg_msg *copy; |
799 | |
800 | /* |
801 | * Create dummy message to copy real message to. |
802 | */ |
803 | copy = load_msg(buf, bufsz); |
804 | if (!IS_ERR(copy)) |
805 | copy->m_ts = bufsz; |
806 | return copy; |
807 | } |
808 | |
809 | static inline void free_copy(struct msg_msg *copy) |
810 | { |
811 | if (copy) |
812 | free_msg(copy); |
813 | } |
814 | #else |
815 | static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) |
816 | { |
817 | return ERR_PTR(-ENOSYS); |
818 | } |
819 | |
820 | static inline void free_copy(struct msg_msg *copy) |
821 | { |
822 | } |
823 | #endif |
824 | |
825 | static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) |
826 | { |
827 | struct msg_msg *msg, *found = NULL; |
828 | long count = 0; |
829 | |
830 | list_for_each_entry(msg, &msq->q_messages, m_list) { |
831 | if (testmsg(msg, *msgtyp, mode) && |
832 | !security_msg_queue_msgrcv(msq, msg, current, |
833 | *msgtyp, mode)) { |
834 | if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { |
835 | *msgtyp = msg->m_type - 1; |
836 | found = msg; |
837 | } else if (mode == SEARCH_NUMBER) { |
838 | if (*msgtyp == count) |
839 | return msg; |
840 | } else |
841 | return msg; |
842 | count++; |
843 | } |
844 | } |
845 | |
846 | return found ?: ERR_PTR(-EAGAIN); |
847 | } |
848 | |
849 | long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg, |
850 | long (*msg_handler)(void __user *, struct msg_msg *, size_t)) |
851 | { |
852 | int mode; |
853 | struct msg_queue *msq; |
854 | struct ipc_namespace *ns; |
855 | struct msg_msg *msg, *copy = NULL; |
856 | WAKE_Q(wake_q); |
857 | |
858 | ns = current->nsproxy->ipc_ns; |
859 | |
860 | if (msqid < 0 || (long) bufsz < 0) |
861 | return -EINVAL; |
862 | |
863 | if (msgflg & MSG_COPY) { |
864 | if ((msgflg & MSG_EXCEPT) || !(msgflg & IPC_NOWAIT)) |
865 | return -EINVAL; |
866 | copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax)); |
867 | if (IS_ERR(copy)) |
868 | return PTR_ERR(copy); |
869 | } |
870 | mode = convert_mode(&msgtyp, msgflg); |
871 | |
872 | rcu_read_lock(); |
873 | msq = msq_obtain_object_check(ns, msqid); |
874 | if (IS_ERR(msq)) { |
875 | rcu_read_unlock(); |
876 | free_copy(copy); |
877 | return PTR_ERR(msq); |
878 | } |
879 | |
880 | for (;;) { |
881 | struct msg_receiver msr_d; |
882 | |
883 | msg = ERR_PTR(-EACCES); |
884 | if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
885 | goto out_unlock1; |
886 | |
887 | ipc_lock_object(&msq->q_perm); |
888 | |
889 | /* raced with RMID? */ |
890 | if (!ipc_valid_object(&msq->q_perm)) { |
891 | msg = ERR_PTR(-EIDRM); |
892 | goto out_unlock0; |
893 | } |
894 | |
895 | msg = find_msg(msq, &msgtyp, mode); |
896 | if (!IS_ERR(msg)) { |
897 | /* |
898 | * Found a suitable message. |
899 | * Unlink it from the queue. |
900 | */ |
901 | if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { |
902 | msg = ERR_PTR(-E2BIG); |
903 | goto out_unlock0; |
904 | } |
905 | /* |
906 | * If we are copying, then do not unlink message and do |
907 | * not update queue parameters. |
908 | */ |
909 | if (msgflg & MSG_COPY) { |
910 | msg = copy_msg(msg, copy); |
911 | goto out_unlock0; |
912 | } |
913 | |
914 | list_del(&msg->m_list); |
915 | msq->q_qnum--; |
916 | msq->q_rtime = get_seconds(); |
917 | msq->q_lrpid = task_tgid_vnr(current); |
918 | msq->q_cbytes -= msg->m_ts; |
919 | atomic_sub(msg->m_ts, &ns->msg_bytes); |
920 | atomic_dec(&ns->msg_hdrs); |
921 | ss_wakeup(msq, &wake_q, false); |
922 | |
923 | goto out_unlock0; |
924 | } |
925 | |
926 | /* No message waiting. Wait for a message */ |
927 | if (msgflg & IPC_NOWAIT) { |
928 | msg = ERR_PTR(-ENOMSG); |
929 | goto out_unlock0; |
930 | } |
931 | |
932 | list_add_tail(&msr_d.r_list, &msq->q_receivers); |
933 | msr_d.r_tsk = current; |
934 | msr_d.r_msgtype = msgtyp; |
935 | msr_d.r_mode = mode; |
936 | if (msgflg & MSG_NOERROR) |
937 | msr_d.r_maxsize = INT_MAX; |
938 | else |
939 | msr_d.r_maxsize = bufsz; |
940 | msr_d.r_msg = ERR_PTR(-EAGAIN); |
941 | __set_current_state(TASK_INTERRUPTIBLE); |
942 | |
943 | ipc_unlock_object(&msq->q_perm); |
944 | rcu_read_unlock(); |
945 | schedule(); |
946 | |
947 | /* |
948 | * Lockless receive, part 1: |
949 | * We don't hold a reference to the queue and getting a |
950 | * reference would defeat the idea of a lockless operation, |
951 | * thus the code relies on rcu to guarantee the existence of |
952 | * msq: |
953 | * Prior to destruction, expunge_all(-EIRDM) changes r_msg. |
954 | * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. |
955 | */ |
956 | rcu_read_lock(); |
957 | |
958 | /* |
959 | * Lockless receive, part 2: |
960 | * The work in pipelined_send() and expunge_all(): |
961 | * - Set pointer to message |
962 | * - Queue the receiver task for later wakeup |
963 | * - Wake up the process after the lock is dropped. |
964 | * |
965 | * Should the process wake up before this wakeup (due to a |
966 | * signal) it will either see the message and continue ... |
967 | */ |
968 | msg = READ_ONCE(msr_d.r_msg); |
969 | if (msg != ERR_PTR(-EAGAIN)) |
970 | goto out_unlock1; |
971 | |
972 | /* |
973 | * ... or see -EAGAIN, acquire the lock to check the message |
974 | * again. |
975 | */ |
976 | ipc_lock_object(&msq->q_perm); |
977 | |
978 | msg = msr_d.r_msg; |
979 | if (msg != ERR_PTR(-EAGAIN)) |
980 | goto out_unlock0; |
981 | |
982 | list_del(&msr_d.r_list); |
983 | if (signal_pending(current)) { |
984 | msg = ERR_PTR(-ERESTARTNOHAND); |
985 | goto out_unlock0; |
986 | } |
987 | |
988 | ipc_unlock_object(&msq->q_perm); |
989 | } |
990 | |
991 | out_unlock0: |
992 | ipc_unlock_object(&msq->q_perm); |
993 | wake_up_q(&wake_q); |
994 | out_unlock1: |
995 | rcu_read_unlock(); |
996 | if (IS_ERR(msg)) { |
997 | free_copy(copy); |
998 | return PTR_ERR(msg); |
999 | } |
1000 | |
1001 | bufsz = msg_handler(buf, msg, bufsz); |
1002 | free_msg(msg); |
1003 | |
1004 | return bufsz; |
1005 | } |
1006 | |
1007 | SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
1008 | long, msgtyp, int, msgflg) |
1009 | { |
1010 | return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill); |
1011 | } |
1012 | |
1013 | |
1014 | void msg_init_ns(struct ipc_namespace *ns) |
1015 | { |
1016 | ns->msg_ctlmax = MSGMAX; |
1017 | ns->msg_ctlmnb = MSGMNB; |
1018 | ns->msg_ctlmni = MSGMNI; |
1019 | |
1020 | atomic_set(&ns->msg_bytes, 0); |
1021 | atomic_set(&ns->msg_hdrs, 0); |
1022 | ipc_init_ids(&ns->ids[IPC_MSG_IDS]); |
1023 | } |
1024 | |
1025 | #ifdef CONFIG_IPC_NS |
1026 | void msg_exit_ns(struct ipc_namespace *ns) |
1027 | { |
1028 | free_ipcs(ns, &msg_ids(ns), freeque); |
1029 | idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); |
1030 | } |
1031 | #endif |
1032 | |
1033 | #ifdef CONFIG_PROC_FS |
1034 | static int sysvipc_msg_proc_show(struct seq_file *s, void *it) |
1035 | { |
1036 | struct user_namespace *user_ns = seq_user_ns(s); |
1037 | struct msg_queue *msq = it; |
1038 | |
1039 | seq_printf(s, |
1040 | "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n", |
1041 | msq->q_perm.key, |
1042 | msq->q_perm.id, |
1043 | msq->q_perm.mode, |
1044 | msq->q_cbytes, |
1045 | msq->q_qnum, |
1046 | msq->q_lspid, |
1047 | msq->q_lrpid, |
1048 | from_kuid_munged(user_ns, msq->q_perm.uid), |
1049 | from_kgid_munged(user_ns, msq->q_perm.gid), |
1050 | from_kuid_munged(user_ns, msq->q_perm.cuid), |
1051 | from_kgid_munged(user_ns, msq->q_perm.cgid), |
1052 | msq->q_stime, |
1053 | msq->q_rtime, |
1054 | msq->q_ctime); |
1055 | |
1056 | return 0; |
1057 | } |
1058 | #endif |
1059 | |
1060 | void __init msg_init(void) |
1061 | { |
1062 | msg_init_ns(&init_ipc_ns); |
1063 | |
1064 | ipc_init_proc_interface("sysvipc/msg", |
1065 | " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", |
1066 | IPC_MSG_IDS, sysvipc_msg_proc_show); |
1067 | } |
1068 |