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