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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 | DEFINE_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 | DEFINE_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 | DEFINE_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 | DEFINE_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 | } |