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