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