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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 | msq->q_qbytes = msqid64.msg_qbytes; |
447 | |
448 | ipc_update_perm(&msqid64.msg_perm, ipcp); |
449 | msq->q_ctime = get_seconds(); |
450 | /* sleeping receivers might be excluded by |
451 | * stricter permissions. |
452 | */ |
453 | expunge_all(msq, -EAGAIN); |
454 | /* sleeping senders might be able to send |
455 | * due to a larger queue size. |
456 | */ |
457 | ss_wakeup(&msq->q_senders, 0); |
458 | break; |
459 | default: |
460 | err = -EINVAL; |
461 | } |
462 | out_unlock: |
463 | msg_unlock(msq); |
464 | out_up: |
465 | up_write(&msg_ids(ns).rw_mutex); |
466 | return err; |
467 | } |
468 | |
469 | SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) |
470 | { |
471 | struct msg_queue *msq; |
472 | int err, version; |
473 | struct ipc_namespace *ns; |
474 | |
475 | if (msqid < 0 || cmd < 0) |
476 | return -EINVAL; |
477 | |
478 | version = ipc_parse_version(&cmd); |
479 | ns = current->nsproxy->ipc_ns; |
480 | |
481 | switch (cmd) { |
482 | case IPC_INFO: |
483 | case MSG_INFO: |
484 | { |
485 | struct msginfo msginfo; |
486 | int max_id; |
487 | |
488 | if (!buf) |
489 | return -EFAULT; |
490 | /* |
491 | * We must not return kernel stack data. |
492 | * due to padding, it's not enough |
493 | * to set all member fields. |
494 | */ |
495 | err = security_msg_queue_msgctl(NULL, cmd); |
496 | if (err) |
497 | return err; |
498 | |
499 | memset(&msginfo, 0, sizeof(msginfo)); |
500 | msginfo.msgmni = ns->msg_ctlmni; |
501 | msginfo.msgmax = ns->msg_ctlmax; |
502 | msginfo.msgmnb = ns->msg_ctlmnb; |
503 | msginfo.msgssz = MSGSSZ; |
504 | msginfo.msgseg = MSGSEG; |
505 | down_read(&msg_ids(ns).rw_mutex); |
506 | if (cmd == MSG_INFO) { |
507 | msginfo.msgpool = msg_ids(ns).in_use; |
508 | msginfo.msgmap = atomic_read(&ns->msg_hdrs); |
509 | msginfo.msgtql = atomic_read(&ns->msg_bytes); |
510 | } else { |
511 | msginfo.msgmap = MSGMAP; |
512 | msginfo.msgpool = MSGPOOL; |
513 | msginfo.msgtql = MSGTQL; |
514 | } |
515 | max_id = ipc_get_maxid(&msg_ids(ns)); |
516 | up_read(&msg_ids(ns).rw_mutex); |
517 | if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) |
518 | return -EFAULT; |
519 | return (max_id < 0) ? 0 : max_id; |
520 | } |
521 | case MSG_STAT: /* msqid is an index rather than a msg queue id */ |
522 | case IPC_STAT: |
523 | { |
524 | struct msqid64_ds tbuf; |
525 | int success_return; |
526 | |
527 | if (!buf) |
528 | return -EFAULT; |
529 | |
530 | if (cmd == MSG_STAT) { |
531 | msq = msg_lock(ns, msqid); |
532 | if (IS_ERR(msq)) |
533 | return PTR_ERR(msq); |
534 | success_return = msq->q_perm.id; |
535 | } else { |
536 | msq = msg_lock_check(ns, msqid); |
537 | if (IS_ERR(msq)) |
538 | return PTR_ERR(msq); |
539 | success_return = 0; |
540 | } |
541 | err = -EACCES; |
542 | if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
543 | goto out_unlock; |
544 | |
545 | err = security_msg_queue_msgctl(msq, cmd); |
546 | if (err) |
547 | goto out_unlock; |
548 | |
549 | memset(&tbuf, 0, sizeof(tbuf)); |
550 | |
551 | kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); |
552 | tbuf.msg_stime = msq->q_stime; |
553 | tbuf.msg_rtime = msq->q_rtime; |
554 | tbuf.msg_ctime = msq->q_ctime; |
555 | tbuf.msg_cbytes = msq->q_cbytes; |
556 | tbuf.msg_qnum = msq->q_qnum; |
557 | tbuf.msg_qbytes = msq->q_qbytes; |
558 | tbuf.msg_lspid = msq->q_lspid; |
559 | tbuf.msg_lrpid = msq->q_lrpid; |
560 | msg_unlock(msq); |
561 | if (copy_msqid_to_user(buf, &tbuf, version)) |
562 | return -EFAULT; |
563 | return success_return; |
564 | } |
565 | case IPC_SET: |
566 | case IPC_RMID: |
567 | err = msgctl_down(ns, msqid, cmd, buf, version); |
568 | return err; |
569 | default: |
570 | return -EINVAL; |
571 | } |
572 | |
573 | out_unlock: |
574 | msg_unlock(msq); |
575 | return err; |
576 | } |
577 | |
578 | static int testmsg(struct msg_msg *msg, long type, int mode) |
579 | { |
580 | switch(mode) |
581 | { |
582 | case SEARCH_ANY: |
583 | return 1; |
584 | case SEARCH_LESSEQUAL: |
585 | if (msg->m_type <=type) |
586 | return 1; |
587 | break; |
588 | case SEARCH_EQUAL: |
589 | if (msg->m_type == type) |
590 | return 1; |
591 | break; |
592 | case SEARCH_NOTEQUAL: |
593 | if (msg->m_type != type) |
594 | return 1; |
595 | break; |
596 | } |
597 | return 0; |
598 | } |
599 | |
600 | static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg) |
601 | { |
602 | struct list_head *tmp; |
603 | |
604 | tmp = msq->q_receivers.next; |
605 | while (tmp != &msq->q_receivers) { |
606 | struct msg_receiver *msr; |
607 | |
608 | msr = list_entry(tmp, struct msg_receiver, r_list); |
609 | tmp = tmp->next; |
610 | if (testmsg(msg, msr->r_msgtype, msr->r_mode) && |
611 | !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, |
612 | msr->r_msgtype, msr->r_mode)) { |
613 | |
614 | list_del(&msr->r_list); |
615 | if (msr->r_maxsize < msg->m_ts) { |
616 | msr->r_msg = NULL; |
617 | wake_up_process(msr->r_tsk); |
618 | smp_mb(); |
619 | msr->r_msg = ERR_PTR(-E2BIG); |
620 | } else { |
621 | msr->r_msg = NULL; |
622 | msq->q_lrpid = task_pid_vnr(msr->r_tsk); |
623 | msq->q_rtime = get_seconds(); |
624 | wake_up_process(msr->r_tsk); |
625 | smp_mb(); |
626 | msr->r_msg = msg; |
627 | |
628 | return 1; |
629 | } |
630 | } |
631 | } |
632 | return 0; |
633 | } |
634 | |
635 | long do_msgsnd(int msqid, long mtype, void __user *mtext, |
636 | size_t msgsz, int msgflg) |
637 | { |
638 | struct msg_queue *msq; |
639 | struct msg_msg *msg; |
640 | int err; |
641 | struct ipc_namespace *ns; |
642 | |
643 | ns = current->nsproxy->ipc_ns; |
644 | |
645 | if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) |
646 | return -EINVAL; |
647 | if (mtype < 1) |
648 | return -EINVAL; |
649 | |
650 | msg = load_msg(mtext, msgsz); |
651 | if (IS_ERR(msg)) |
652 | return PTR_ERR(msg); |
653 | |
654 | msg->m_type = mtype; |
655 | msg->m_ts = msgsz; |
656 | |
657 | msq = msg_lock_check(ns, msqid); |
658 | if (IS_ERR(msq)) { |
659 | err = PTR_ERR(msq); |
660 | goto out_free; |
661 | } |
662 | |
663 | for (;;) { |
664 | struct msg_sender s; |
665 | |
666 | err = -EACCES; |
667 | if (ipcperms(ns, &msq->q_perm, S_IWUGO)) |
668 | goto out_unlock_free; |
669 | |
670 | err = security_msg_queue_msgsnd(msq, msg, msgflg); |
671 | if (err) |
672 | goto out_unlock_free; |
673 | |
674 | if (msgsz + msq->q_cbytes <= msq->q_qbytes && |
675 | 1 + msq->q_qnum <= msq->q_qbytes) { |
676 | break; |
677 | } |
678 | |
679 | /* queue full, wait: */ |
680 | if (msgflg & IPC_NOWAIT) { |
681 | err = -EAGAIN; |
682 | goto out_unlock_free; |
683 | } |
684 | ss_add(msq, &s); |
685 | ipc_rcu_getref(msq); |
686 | msg_unlock(msq); |
687 | schedule(); |
688 | |
689 | ipc_lock_by_ptr(&msq->q_perm); |
690 | ipc_rcu_putref(msq); |
691 | if (msq->q_perm.deleted) { |
692 | err = -EIDRM; |
693 | goto out_unlock_free; |
694 | } |
695 | ss_del(&s); |
696 | |
697 | if (signal_pending(current)) { |
698 | err = -ERESTARTNOHAND; |
699 | goto out_unlock_free; |
700 | } |
701 | } |
702 | |
703 | msq->q_lspid = task_tgid_vnr(current); |
704 | msq->q_stime = get_seconds(); |
705 | |
706 | if (!pipelined_send(msq, msg)) { |
707 | /* no one is waiting for this message, enqueue it */ |
708 | list_add_tail(&msg->m_list, &msq->q_messages); |
709 | msq->q_cbytes += msgsz; |
710 | msq->q_qnum++; |
711 | atomic_add(msgsz, &ns->msg_bytes); |
712 | atomic_inc(&ns->msg_hdrs); |
713 | } |
714 | |
715 | err = 0; |
716 | msg = NULL; |
717 | |
718 | out_unlock_free: |
719 | msg_unlock(msq); |
720 | out_free: |
721 | if (msg != NULL) |
722 | free_msg(msg); |
723 | return err; |
724 | } |
725 | |
726 | SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
727 | int, msgflg) |
728 | { |
729 | long mtype; |
730 | |
731 | if (get_user(mtype, &msgp->mtype)) |
732 | return -EFAULT; |
733 | return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); |
734 | } |
735 | |
736 | static inline int convert_mode(long *msgtyp, int msgflg) |
737 | { |
738 | /* |
739 | * find message of correct type. |
740 | * msgtyp = 0 => get first. |
741 | * msgtyp > 0 => get first message of matching type. |
742 | * msgtyp < 0 => get message with least type must be < abs(msgtype). |
743 | */ |
744 | if (*msgtyp == 0) |
745 | return SEARCH_ANY; |
746 | if (*msgtyp < 0) { |
747 | *msgtyp = -*msgtyp; |
748 | return SEARCH_LESSEQUAL; |
749 | } |
750 | if (msgflg & MSG_EXCEPT) |
751 | return SEARCH_NOTEQUAL; |
752 | return SEARCH_EQUAL; |
753 | } |
754 | |
755 | long do_msgrcv(int msqid, long *pmtype, void __user *mtext, |
756 | size_t msgsz, long msgtyp, int msgflg) |
757 | { |
758 | struct msg_queue *msq; |
759 | struct msg_msg *msg; |
760 | int mode; |
761 | struct ipc_namespace *ns; |
762 | |
763 | if (msqid < 0 || (long) msgsz < 0) |
764 | return -EINVAL; |
765 | mode = convert_mode(&msgtyp, msgflg); |
766 | ns = current->nsproxy->ipc_ns; |
767 | |
768 | msq = msg_lock_check(ns, msqid); |
769 | if (IS_ERR(msq)) |
770 | return PTR_ERR(msq); |
771 | |
772 | for (;;) { |
773 | struct msg_receiver msr_d; |
774 | struct list_head *tmp; |
775 | |
776 | msg = ERR_PTR(-EACCES); |
777 | if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
778 | goto out_unlock; |
779 | |
780 | msg = ERR_PTR(-EAGAIN); |
781 | tmp = msq->q_messages.next; |
782 | while (tmp != &msq->q_messages) { |
783 | struct msg_msg *walk_msg; |
784 | |
785 | walk_msg = list_entry(tmp, struct msg_msg, m_list); |
786 | if (testmsg(walk_msg, msgtyp, mode) && |
787 | !security_msg_queue_msgrcv(msq, walk_msg, current, |
788 | msgtyp, mode)) { |
789 | |
790 | msg = walk_msg; |
791 | if (mode == SEARCH_LESSEQUAL && |
792 | walk_msg->m_type != 1) { |
793 | msg = walk_msg; |
794 | msgtyp = walk_msg->m_type - 1; |
795 | } else { |
796 | msg = walk_msg; |
797 | break; |
798 | } |
799 | } |
800 | tmp = tmp->next; |
801 | } |
802 | if (!IS_ERR(msg)) { |
803 | /* |
804 | * Found a suitable message. |
805 | * Unlink it from the queue. |
806 | */ |
807 | if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { |
808 | msg = ERR_PTR(-E2BIG); |
809 | goto out_unlock; |
810 | } |
811 | list_del(&msg->m_list); |
812 | msq->q_qnum--; |
813 | msq->q_rtime = get_seconds(); |
814 | msq->q_lrpid = task_tgid_vnr(current); |
815 | msq->q_cbytes -= msg->m_ts; |
816 | atomic_sub(msg->m_ts, &ns->msg_bytes); |
817 | atomic_dec(&ns->msg_hdrs); |
818 | ss_wakeup(&msq->q_senders, 0); |
819 | msg_unlock(msq); |
820 | break; |
821 | } |
822 | /* No message waiting. Wait for a message */ |
823 | if (msgflg & IPC_NOWAIT) { |
824 | msg = ERR_PTR(-ENOMSG); |
825 | goto out_unlock; |
826 | } |
827 | list_add_tail(&msr_d.r_list, &msq->q_receivers); |
828 | msr_d.r_tsk = current; |
829 | msr_d.r_msgtype = msgtyp; |
830 | msr_d.r_mode = mode; |
831 | if (msgflg & MSG_NOERROR) |
832 | msr_d.r_maxsize = INT_MAX; |
833 | else |
834 | msr_d.r_maxsize = msgsz; |
835 | msr_d.r_msg = ERR_PTR(-EAGAIN); |
836 | current->state = TASK_INTERRUPTIBLE; |
837 | msg_unlock(msq); |
838 | |
839 | schedule(); |
840 | |
841 | /* Lockless receive, part 1: |
842 | * Disable preemption. We don't hold a reference to the queue |
843 | * and getting a reference would defeat the idea of a lockless |
844 | * operation, thus the code relies on rcu to guarantee the |
845 | * existence of msq: |
846 | * Prior to destruction, expunge_all(-EIRDM) changes r_msg. |
847 | * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. |
848 | * rcu_read_lock() prevents preemption between reading r_msg |
849 | * and the spin_lock() inside ipc_lock_by_ptr(). |
850 | */ |
851 | rcu_read_lock(); |
852 | |
853 | /* Lockless receive, part 2: |
854 | * Wait until pipelined_send or expunge_all are outside of |
855 | * wake_up_process(). There is a race with exit(), see |
856 | * ipc/mqueue.c for the details. |
857 | */ |
858 | msg = (struct msg_msg*)msr_d.r_msg; |
859 | while (msg == NULL) { |
860 | cpu_relax(); |
861 | msg = (struct msg_msg *)msr_d.r_msg; |
862 | } |
863 | |
864 | /* Lockless receive, part 3: |
865 | * If there is a message or an error then accept it without |
866 | * locking. |
867 | */ |
868 | if (msg != ERR_PTR(-EAGAIN)) { |
869 | rcu_read_unlock(); |
870 | break; |
871 | } |
872 | |
873 | /* Lockless receive, part 3: |
874 | * Acquire the queue spinlock. |
875 | */ |
876 | ipc_lock_by_ptr(&msq->q_perm); |
877 | rcu_read_unlock(); |
878 | |
879 | /* Lockless receive, part 4: |
880 | * Repeat test after acquiring the spinlock. |
881 | */ |
882 | msg = (struct msg_msg*)msr_d.r_msg; |
883 | if (msg != ERR_PTR(-EAGAIN)) |
884 | goto out_unlock; |
885 | |
886 | list_del(&msr_d.r_list); |
887 | if (signal_pending(current)) { |
888 | msg = ERR_PTR(-ERESTARTNOHAND); |
889 | out_unlock: |
890 | msg_unlock(msq); |
891 | break; |
892 | } |
893 | } |
894 | if (IS_ERR(msg)) |
895 | return PTR_ERR(msg); |
896 | |
897 | msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz; |
898 | *pmtype = msg->m_type; |
899 | if (store_msg(mtext, msg, msgsz)) |
900 | msgsz = -EFAULT; |
901 | |
902 | free_msg(msg); |
903 | |
904 | return msgsz; |
905 | } |
906 | |
907 | SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
908 | long, msgtyp, int, msgflg) |
909 | { |
910 | long err, mtype; |
911 | |
912 | err = do_msgrcv(msqid, &mtype, msgp->mtext, msgsz, msgtyp, msgflg); |
913 | if (err < 0) |
914 | goto out; |
915 | |
916 | if (put_user(mtype, &msgp->mtype)) |
917 | err = -EFAULT; |
918 | out: |
919 | return err; |
920 | } |
921 | |
922 | #ifdef CONFIG_PROC_FS |
923 | static int sysvipc_msg_proc_show(struct seq_file *s, void *it) |
924 | { |
925 | struct msg_queue *msq = it; |
926 | |
927 | return seq_printf(s, |
928 | "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n", |
929 | msq->q_perm.key, |
930 | msq->q_perm.id, |
931 | msq->q_perm.mode, |
932 | msq->q_cbytes, |
933 | msq->q_qnum, |
934 | msq->q_lspid, |
935 | msq->q_lrpid, |
936 | msq->q_perm.uid, |
937 | msq->q_perm.gid, |
938 | msq->q_perm.cuid, |
939 | msq->q_perm.cgid, |
940 | msq->q_stime, |
941 | msq->q_rtime, |
942 | msq->q_ctime); |
943 | } |
944 | #endif |
945 |
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