Commit | Line | Data |
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1da177e4 LT |
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 | |
624dffcb | 15 | * (c) 1999 Manfred Spraul <manfred@colorfullife.com> |
1da177e4 LT |
16 | */ |
17 | ||
c59ede7b | 18 | #include <linux/capability.h> |
1da177e4 LT |
19 | #include <linux/config.h> |
20 | #include <linux/slab.h> | |
21 | #include <linux/msg.h> | |
22 | #include <linux/spinlock.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/proc_fs.h> | |
25 | #include <linux/list.h> | |
26 | #include <linux/security.h> | |
27 | #include <linux/sched.h> | |
28 | #include <linux/syscalls.h> | |
29 | #include <linux/audit.h> | |
19b4946c | 30 | #include <linux/seq_file.h> |
1da177e4 LT |
31 | #include <asm/current.h> |
32 | #include <asm/uaccess.h> | |
33 | #include "util.h" | |
34 | ||
35 | /* sysctl: */ | |
36 | int msg_ctlmax = MSGMAX; | |
37 | int msg_ctlmnb = MSGMNB; | |
38 | int msg_ctlmni = MSGMNI; | |
39 | ||
40 | /* one msg_receiver structure for each sleeping receiver */ | |
41 | struct msg_receiver { | |
42 | struct list_head r_list; | |
43 | struct task_struct* r_tsk; | |
44 | ||
45 | int r_mode; | |
46 | long r_msgtype; | |
47 | long r_maxsize; | |
48 | ||
49 | struct msg_msg* volatile r_msg; | |
50 | }; | |
51 | ||
52 | /* one msg_sender for each sleeping sender */ | |
53 | struct msg_sender { | |
54 | struct list_head list; | |
55 | struct task_struct* tsk; | |
56 | }; | |
57 | ||
58 | #define SEARCH_ANY 1 | |
59 | #define SEARCH_EQUAL 2 | |
60 | #define SEARCH_NOTEQUAL 3 | |
61 | #define SEARCH_LESSEQUAL 4 | |
62 | ||
63 | static atomic_t msg_bytes = ATOMIC_INIT(0); | |
64 | static atomic_t msg_hdrs = ATOMIC_INIT(0); | |
65 | ||
66 | static struct ipc_ids msg_ids; | |
67 | ||
68 | #define msg_lock(id) ((struct msg_queue*)ipc_lock(&msg_ids,id)) | |
69 | #define msg_unlock(msq) ipc_unlock(&(msq)->q_perm) | |
70 | #define msg_rmid(id) ((struct msg_queue*)ipc_rmid(&msg_ids,id)) | |
71 | #define msg_checkid(msq, msgid) \ | |
72 | ipc_checkid(&msg_ids,&msq->q_perm,msgid) | |
73 | #define msg_buildid(id, seq) \ | |
74 | ipc_buildid(&msg_ids, id, seq) | |
75 | ||
76 | static void freeque (struct msg_queue *msq, int id); | |
77 | static int newque (key_t key, int msgflg); | |
78 | #ifdef CONFIG_PROC_FS | |
19b4946c | 79 | static int sysvipc_msg_proc_show(struct seq_file *s, void *it); |
1da177e4 LT |
80 | #endif |
81 | ||
82 | void __init msg_init (void) | |
83 | { | |
84 | ipc_init_ids(&msg_ids,msg_ctlmni); | |
19b4946c MW |
85 | ipc_init_proc_interface("sysvipc/msg", |
86 | " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", | |
87 | &msg_ids, | |
88 | sysvipc_msg_proc_show); | |
1da177e4 LT |
89 | } |
90 | ||
91 | static int newque (key_t key, int msgflg) | |
92 | { | |
93 | int id; | |
94 | int retval; | |
95 | struct msg_queue *msq; | |
96 | ||
97 | msq = ipc_rcu_alloc(sizeof(*msq)); | |
98 | if (!msq) | |
99 | return -ENOMEM; | |
100 | ||
101 | msq->q_perm.mode = (msgflg & S_IRWXUGO); | |
102 | msq->q_perm.key = key; | |
103 | ||
104 | msq->q_perm.security = NULL; | |
105 | retval = security_msg_queue_alloc(msq); | |
106 | if (retval) { | |
107 | ipc_rcu_putref(msq); | |
108 | return retval; | |
109 | } | |
110 | ||
111 | id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni); | |
112 | if(id == -1) { | |
113 | security_msg_queue_free(msq); | |
114 | ipc_rcu_putref(msq); | |
115 | return -ENOSPC; | |
116 | } | |
117 | ||
19b4946c | 118 | msq->q_id = msg_buildid(id,msq->q_perm.seq); |
1da177e4 LT |
119 | msq->q_stime = msq->q_rtime = 0; |
120 | msq->q_ctime = get_seconds(); | |
121 | msq->q_cbytes = msq->q_qnum = 0; | |
122 | msq->q_qbytes = msg_ctlmnb; | |
123 | msq->q_lspid = msq->q_lrpid = 0; | |
124 | INIT_LIST_HEAD(&msq->q_messages); | |
125 | INIT_LIST_HEAD(&msq->q_receivers); | |
126 | INIT_LIST_HEAD(&msq->q_senders); | |
127 | msg_unlock(msq); | |
128 | ||
19b4946c | 129 | return msq->q_id; |
1da177e4 LT |
130 | } |
131 | ||
132 | static inline void ss_add(struct msg_queue* msq, struct msg_sender* mss) | |
133 | { | |
134 | mss->tsk=current; | |
135 | current->state=TASK_INTERRUPTIBLE; | |
136 | list_add_tail(&mss->list,&msq->q_senders); | |
137 | } | |
138 | ||
139 | static inline void ss_del(struct msg_sender* mss) | |
140 | { | |
141 | if(mss->list.next != NULL) | |
142 | list_del(&mss->list); | |
143 | } | |
144 | ||
145 | static void ss_wakeup(struct list_head* h, int kill) | |
146 | { | |
147 | struct list_head *tmp; | |
148 | ||
149 | tmp = h->next; | |
150 | while (tmp != h) { | |
151 | struct msg_sender* mss; | |
152 | ||
153 | mss = list_entry(tmp,struct msg_sender,list); | |
154 | tmp = tmp->next; | |
155 | if(kill) | |
156 | mss->list.next=NULL; | |
157 | wake_up_process(mss->tsk); | |
158 | } | |
159 | } | |
160 | ||
161 | static void expunge_all(struct msg_queue* msq, int res) | |
162 | { | |
163 | struct list_head *tmp; | |
164 | ||
165 | tmp = msq->q_receivers.next; | |
166 | while (tmp != &msq->q_receivers) { | |
167 | struct msg_receiver* msr; | |
168 | ||
169 | msr = list_entry(tmp,struct msg_receiver,r_list); | |
170 | tmp = tmp->next; | |
171 | msr->r_msg = NULL; | |
172 | wake_up_process(msr->r_tsk); | |
173 | smp_mb(); | |
174 | msr->r_msg = ERR_PTR(res); | |
175 | } | |
176 | } | |
177 | /* | |
178 | * freeque() wakes up waiters on the sender and receiver waiting queue, | |
179 | * removes the message queue from message queue ID | |
180 | * array, and cleans up all the messages associated with this queue. | |
181 | * | |
182 | * msg_ids.sem and the spinlock for this message queue is hold | |
183 | * before freeque() is called. msg_ids.sem remains locked on exit. | |
184 | */ | |
185 | static void freeque (struct msg_queue *msq, int id) | |
186 | { | |
187 | struct list_head *tmp; | |
188 | ||
189 | expunge_all(msq,-EIDRM); | |
190 | ss_wakeup(&msq->q_senders,1); | |
191 | msq = msg_rmid(id); | |
192 | msg_unlock(msq); | |
193 | ||
194 | tmp = msq->q_messages.next; | |
195 | while(tmp != &msq->q_messages) { | |
196 | struct msg_msg* msg = list_entry(tmp,struct msg_msg,m_list); | |
197 | tmp = tmp->next; | |
198 | atomic_dec(&msg_hdrs); | |
199 | free_msg(msg); | |
200 | } | |
201 | atomic_sub(msq->q_cbytes, &msg_bytes); | |
202 | security_msg_queue_free(msq); | |
203 | ipc_rcu_putref(msq); | |
204 | } | |
205 | ||
206 | asmlinkage long sys_msgget (key_t key, int msgflg) | |
207 | { | |
208 | int id, ret = -EPERM; | |
209 | struct msg_queue *msq; | |
210 | ||
211 | down(&msg_ids.sem); | |
212 | if (key == IPC_PRIVATE) | |
213 | ret = newque(key, msgflg); | |
214 | else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */ | |
215 | if (!(msgflg & IPC_CREAT)) | |
216 | ret = -ENOENT; | |
217 | else | |
218 | ret = newque(key, msgflg); | |
219 | } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) { | |
220 | ret = -EEXIST; | |
221 | } else { | |
222 | msq = msg_lock(id); | |
223 | if(msq==NULL) | |
224 | BUG(); | |
225 | if (ipcperms(&msq->q_perm, msgflg)) | |
226 | ret = -EACCES; | |
227 | else { | |
228 | int qid = msg_buildid(id, msq->q_perm.seq); | |
229 | ret = security_msg_queue_associate(msq, msgflg); | |
230 | if (!ret) | |
231 | ret = qid; | |
232 | } | |
233 | msg_unlock(msq); | |
234 | } | |
235 | up(&msg_ids.sem); | |
236 | return ret; | |
237 | } | |
238 | ||
239 | static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) | |
240 | { | |
241 | switch(version) { | |
242 | case IPC_64: | |
243 | return copy_to_user (buf, in, sizeof(*in)); | |
244 | case IPC_OLD: | |
245 | { | |
246 | struct msqid_ds out; | |
247 | ||
248 | memset(&out,0,sizeof(out)); | |
249 | ||
250 | ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); | |
251 | ||
252 | out.msg_stime = in->msg_stime; | |
253 | out.msg_rtime = in->msg_rtime; | |
254 | out.msg_ctime = in->msg_ctime; | |
255 | ||
256 | if(in->msg_cbytes > USHRT_MAX) | |
257 | out.msg_cbytes = USHRT_MAX; | |
258 | else | |
259 | out.msg_cbytes = in->msg_cbytes; | |
260 | out.msg_lcbytes = in->msg_cbytes; | |
261 | ||
262 | if(in->msg_qnum > USHRT_MAX) | |
263 | out.msg_qnum = USHRT_MAX; | |
264 | else | |
265 | out.msg_qnum = in->msg_qnum; | |
266 | ||
267 | if(in->msg_qbytes > USHRT_MAX) | |
268 | out.msg_qbytes = USHRT_MAX; | |
269 | else | |
270 | out.msg_qbytes = in->msg_qbytes; | |
271 | out.msg_lqbytes = in->msg_qbytes; | |
272 | ||
273 | out.msg_lspid = in->msg_lspid; | |
274 | out.msg_lrpid = in->msg_lrpid; | |
275 | ||
276 | return copy_to_user (buf, &out, sizeof(out)); | |
277 | } | |
278 | default: | |
279 | return -EINVAL; | |
280 | } | |
281 | } | |
282 | ||
283 | struct msq_setbuf { | |
284 | unsigned long qbytes; | |
285 | uid_t uid; | |
286 | gid_t gid; | |
287 | mode_t mode; | |
288 | }; | |
289 | ||
290 | static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version) | |
291 | { | |
292 | switch(version) { | |
293 | case IPC_64: | |
294 | { | |
295 | struct msqid64_ds tbuf; | |
296 | ||
297 | if (copy_from_user (&tbuf, buf, sizeof (tbuf))) | |
298 | return -EFAULT; | |
299 | ||
300 | out->qbytes = tbuf.msg_qbytes; | |
301 | out->uid = tbuf.msg_perm.uid; | |
302 | out->gid = tbuf.msg_perm.gid; | |
303 | out->mode = tbuf.msg_perm.mode; | |
304 | ||
305 | return 0; | |
306 | } | |
307 | case IPC_OLD: | |
308 | { | |
309 | struct msqid_ds tbuf_old; | |
310 | ||
311 | if (copy_from_user (&tbuf_old, buf, sizeof (tbuf_old))) | |
312 | return -EFAULT; | |
313 | ||
314 | out->uid = tbuf_old.msg_perm.uid; | |
315 | out->gid = tbuf_old.msg_perm.gid; | |
316 | out->mode = tbuf_old.msg_perm.mode; | |
317 | ||
318 | if(tbuf_old.msg_qbytes == 0) | |
319 | out->qbytes = tbuf_old.msg_lqbytes; | |
320 | else | |
321 | out->qbytes = tbuf_old.msg_qbytes; | |
322 | ||
323 | return 0; | |
324 | } | |
325 | default: | |
326 | return -EINVAL; | |
327 | } | |
328 | } | |
329 | ||
330 | asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds __user *buf) | |
331 | { | |
332 | int err, version; | |
333 | struct msg_queue *msq; | |
334 | struct msq_setbuf setbuf; | |
335 | struct kern_ipc_perm *ipcp; | |
336 | ||
337 | if (msqid < 0 || cmd < 0) | |
338 | return -EINVAL; | |
339 | ||
340 | version = ipc_parse_version(&cmd); | |
341 | ||
342 | switch (cmd) { | |
343 | case IPC_INFO: | |
344 | case MSG_INFO: | |
345 | { | |
346 | struct msginfo msginfo; | |
347 | int max_id; | |
348 | if (!buf) | |
349 | return -EFAULT; | |
350 | /* We must not return kernel stack data. | |
351 | * due to padding, it's not enough | |
352 | * to set all member fields. | |
353 | */ | |
354 | ||
355 | err = security_msg_queue_msgctl(NULL, cmd); | |
356 | if (err) | |
357 | return err; | |
358 | ||
359 | memset(&msginfo,0,sizeof(msginfo)); | |
360 | msginfo.msgmni = msg_ctlmni; | |
361 | msginfo.msgmax = msg_ctlmax; | |
362 | msginfo.msgmnb = msg_ctlmnb; | |
363 | msginfo.msgssz = MSGSSZ; | |
364 | msginfo.msgseg = MSGSEG; | |
365 | down(&msg_ids.sem); | |
366 | if (cmd == MSG_INFO) { | |
367 | msginfo.msgpool = msg_ids.in_use; | |
368 | msginfo.msgmap = atomic_read(&msg_hdrs); | |
369 | msginfo.msgtql = atomic_read(&msg_bytes); | |
370 | } else { | |
371 | msginfo.msgmap = MSGMAP; | |
372 | msginfo.msgpool = MSGPOOL; | |
373 | msginfo.msgtql = MSGTQL; | |
374 | } | |
375 | max_id = msg_ids.max_id; | |
376 | up(&msg_ids.sem); | |
377 | if (copy_to_user (buf, &msginfo, sizeof(struct msginfo))) | |
378 | return -EFAULT; | |
379 | return (max_id < 0) ? 0: max_id; | |
380 | } | |
381 | case MSG_STAT: | |
382 | case IPC_STAT: | |
383 | { | |
384 | struct msqid64_ds tbuf; | |
385 | int success_return; | |
386 | if (!buf) | |
387 | return -EFAULT; | |
388 | if(cmd == MSG_STAT && msqid >= msg_ids.entries->size) | |
389 | return -EINVAL; | |
390 | ||
391 | memset(&tbuf,0,sizeof(tbuf)); | |
392 | ||
393 | msq = msg_lock(msqid); | |
394 | if (msq == NULL) | |
395 | return -EINVAL; | |
396 | ||
397 | if(cmd == MSG_STAT) { | |
398 | success_return = msg_buildid(msqid, msq->q_perm.seq); | |
399 | } else { | |
400 | err = -EIDRM; | |
401 | if (msg_checkid(msq,msqid)) | |
402 | goto out_unlock; | |
403 | success_return = 0; | |
404 | } | |
405 | err = -EACCES; | |
406 | if (ipcperms (&msq->q_perm, S_IRUGO)) | |
407 | goto out_unlock; | |
408 | ||
409 | err = security_msg_queue_msgctl(msq, cmd); | |
410 | if (err) | |
411 | goto out_unlock; | |
412 | ||
413 | kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); | |
414 | tbuf.msg_stime = msq->q_stime; | |
415 | tbuf.msg_rtime = msq->q_rtime; | |
416 | tbuf.msg_ctime = msq->q_ctime; | |
417 | tbuf.msg_cbytes = msq->q_cbytes; | |
418 | tbuf.msg_qnum = msq->q_qnum; | |
419 | tbuf.msg_qbytes = msq->q_qbytes; | |
420 | tbuf.msg_lspid = msq->q_lspid; | |
421 | tbuf.msg_lrpid = msq->q_lrpid; | |
422 | msg_unlock(msq); | |
423 | if (copy_msqid_to_user(buf, &tbuf, version)) | |
424 | return -EFAULT; | |
425 | return success_return; | |
426 | } | |
427 | case IPC_SET: | |
428 | if (!buf) | |
429 | return -EFAULT; | |
430 | if (copy_msqid_from_user (&setbuf, buf, version)) | |
431 | return -EFAULT; | |
432 | if ((err = audit_ipc_perms(setbuf.qbytes, setbuf.uid, setbuf.gid, setbuf.mode))) | |
433 | return err; | |
434 | break; | |
435 | case IPC_RMID: | |
436 | break; | |
437 | default: | |
438 | return -EINVAL; | |
439 | } | |
440 | ||
441 | down(&msg_ids.sem); | |
442 | msq = msg_lock(msqid); | |
443 | err=-EINVAL; | |
444 | if (msq == NULL) | |
445 | goto out_up; | |
446 | ||
447 | err = -EIDRM; | |
448 | if (msg_checkid(msq,msqid)) | |
449 | goto out_unlock_up; | |
450 | ipcp = &msq->q_perm; | |
451 | err = -EPERM; | |
452 | if (current->euid != ipcp->cuid && | |
453 | current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) | |
454 | /* We _could_ check for CAP_CHOWN above, but we don't */ | |
455 | goto out_unlock_up; | |
456 | ||
457 | err = security_msg_queue_msgctl(msq, cmd); | |
458 | if (err) | |
459 | goto out_unlock_up; | |
460 | ||
461 | switch (cmd) { | |
462 | case IPC_SET: | |
463 | { | |
464 | err = -EPERM; | |
465 | if (setbuf.qbytes > msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) | |
466 | goto out_unlock_up; | |
467 | ||
468 | msq->q_qbytes = setbuf.qbytes; | |
469 | ||
470 | ipcp->uid = setbuf.uid; | |
471 | ipcp->gid = setbuf.gid; | |
472 | ipcp->mode = (ipcp->mode & ~S_IRWXUGO) | | |
473 | (S_IRWXUGO & setbuf.mode); | |
474 | msq->q_ctime = get_seconds(); | |
475 | /* sleeping receivers might be excluded by | |
476 | * stricter permissions. | |
477 | */ | |
478 | expunge_all(msq,-EAGAIN); | |
479 | /* sleeping senders might be able to send | |
480 | * due to a larger queue size. | |
481 | */ | |
482 | ss_wakeup(&msq->q_senders,0); | |
483 | msg_unlock(msq); | |
484 | break; | |
485 | } | |
486 | case IPC_RMID: | |
487 | freeque (msq, msqid); | |
488 | break; | |
489 | } | |
490 | err = 0; | |
491 | out_up: | |
492 | up(&msg_ids.sem); | |
493 | return err; | |
494 | out_unlock_up: | |
495 | msg_unlock(msq); | |
496 | goto out_up; | |
497 | out_unlock: | |
498 | msg_unlock(msq); | |
499 | return err; | |
500 | } | |
501 | ||
502 | static int testmsg(struct msg_msg* msg,long type,int mode) | |
503 | { | |
504 | switch(mode) | |
505 | { | |
506 | case SEARCH_ANY: | |
507 | return 1; | |
508 | case SEARCH_LESSEQUAL: | |
509 | if(msg->m_type <=type) | |
510 | return 1; | |
511 | break; | |
512 | case SEARCH_EQUAL: | |
513 | if(msg->m_type == type) | |
514 | return 1; | |
515 | break; | |
516 | case SEARCH_NOTEQUAL: | |
517 | if(msg->m_type != type) | |
518 | return 1; | |
519 | break; | |
520 | } | |
521 | return 0; | |
522 | } | |
523 | ||
524 | static inline int pipelined_send(struct msg_queue* msq, struct msg_msg* msg) | |
525 | { | |
526 | struct list_head* tmp; | |
527 | ||
528 | tmp = msq->q_receivers.next; | |
529 | while (tmp != &msq->q_receivers) { | |
530 | struct msg_receiver* msr; | |
531 | msr = list_entry(tmp,struct msg_receiver,r_list); | |
532 | tmp = tmp->next; | |
533 | if(testmsg(msg,msr->r_msgtype,msr->r_mode) && | |
534 | !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, msr->r_msgtype, msr->r_mode)) { | |
535 | list_del(&msr->r_list); | |
536 | if(msr->r_maxsize < msg->m_ts) { | |
537 | msr->r_msg = NULL; | |
538 | wake_up_process(msr->r_tsk); | |
539 | smp_mb(); | |
540 | msr->r_msg = ERR_PTR(-E2BIG); | |
541 | } else { | |
542 | msr->r_msg = NULL; | |
543 | msq->q_lrpid = msr->r_tsk->pid; | |
544 | msq->q_rtime = get_seconds(); | |
545 | wake_up_process(msr->r_tsk); | |
546 | smp_mb(); | |
547 | msr->r_msg = msg; | |
548 | return 1; | |
549 | } | |
550 | } | |
551 | } | |
552 | return 0; | |
553 | } | |
554 | ||
555 | asmlinkage long sys_msgsnd (int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg) | |
556 | { | |
557 | struct msg_queue *msq; | |
558 | struct msg_msg *msg; | |
559 | long mtype; | |
560 | int err; | |
561 | ||
562 | if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0) | |
563 | return -EINVAL; | |
564 | if (get_user(mtype, &msgp->mtype)) | |
565 | return -EFAULT; | |
566 | if (mtype < 1) | |
567 | return -EINVAL; | |
568 | ||
569 | msg = load_msg(msgp->mtext, msgsz); | |
570 | if(IS_ERR(msg)) | |
571 | return PTR_ERR(msg); | |
572 | ||
573 | msg->m_type = mtype; | |
574 | msg->m_ts = msgsz; | |
575 | ||
576 | msq = msg_lock(msqid); | |
577 | err=-EINVAL; | |
578 | if(msq==NULL) | |
579 | goto out_free; | |
580 | ||
581 | err= -EIDRM; | |
582 | if (msg_checkid(msq,msqid)) | |
583 | goto out_unlock_free; | |
584 | ||
585 | for (;;) { | |
586 | struct msg_sender s; | |
587 | ||
588 | err=-EACCES; | |
589 | if (ipcperms(&msq->q_perm, S_IWUGO)) | |
590 | goto out_unlock_free; | |
591 | ||
592 | err = security_msg_queue_msgsnd(msq, msg, msgflg); | |
593 | if (err) | |
594 | goto out_unlock_free; | |
595 | ||
596 | if(msgsz + msq->q_cbytes <= msq->q_qbytes && | |
597 | 1 + msq->q_qnum <= msq->q_qbytes) { | |
598 | break; | |
599 | } | |
600 | ||
601 | /* queue full, wait: */ | |
602 | if(msgflg&IPC_NOWAIT) { | |
603 | err=-EAGAIN; | |
604 | goto out_unlock_free; | |
605 | } | |
606 | ss_add(msq, &s); | |
607 | ipc_rcu_getref(msq); | |
608 | msg_unlock(msq); | |
609 | schedule(); | |
610 | ||
611 | ipc_lock_by_ptr(&msq->q_perm); | |
612 | ipc_rcu_putref(msq); | |
613 | if (msq->q_perm.deleted) { | |
614 | err = -EIDRM; | |
615 | goto out_unlock_free; | |
616 | } | |
617 | ss_del(&s); | |
618 | ||
619 | if (signal_pending(current)) { | |
620 | err=-ERESTARTNOHAND; | |
621 | goto out_unlock_free; | |
622 | } | |
623 | } | |
624 | ||
625 | msq->q_lspid = current->tgid; | |
626 | msq->q_stime = get_seconds(); | |
627 | ||
628 | if(!pipelined_send(msq,msg)) { | |
629 | /* noone is waiting for this message, enqueue it */ | |
630 | list_add_tail(&msg->m_list,&msq->q_messages); | |
631 | msq->q_cbytes += msgsz; | |
632 | msq->q_qnum++; | |
633 | atomic_add(msgsz,&msg_bytes); | |
634 | atomic_inc(&msg_hdrs); | |
635 | } | |
636 | ||
637 | err = 0; | |
638 | msg = NULL; | |
639 | ||
640 | out_unlock_free: | |
641 | msg_unlock(msq); | |
642 | out_free: | |
643 | if(msg!=NULL) | |
644 | free_msg(msg); | |
645 | return err; | |
646 | } | |
647 | ||
648 | static inline int convert_mode(long* msgtyp, int msgflg) | |
649 | { | |
650 | /* | |
651 | * find message of correct type. | |
652 | * msgtyp = 0 => get first. | |
653 | * msgtyp > 0 => get first message of matching type. | |
654 | * msgtyp < 0 => get message with least type must be < abs(msgtype). | |
655 | */ | |
656 | if(*msgtyp==0) | |
657 | return SEARCH_ANY; | |
658 | if(*msgtyp<0) { | |
659 | *msgtyp=-(*msgtyp); | |
660 | return SEARCH_LESSEQUAL; | |
661 | } | |
662 | if(msgflg & MSG_EXCEPT) | |
663 | return SEARCH_NOTEQUAL; | |
664 | return SEARCH_EQUAL; | |
665 | } | |
666 | ||
667 | asmlinkage long sys_msgrcv (int msqid, struct msgbuf __user *msgp, size_t msgsz, | |
668 | long msgtyp, int msgflg) | |
669 | { | |
670 | struct msg_queue *msq; | |
671 | struct msg_msg *msg; | |
672 | int mode; | |
673 | ||
674 | if (msqid < 0 || (long) msgsz < 0) | |
675 | return -EINVAL; | |
676 | mode = convert_mode(&msgtyp,msgflg); | |
677 | ||
678 | msq = msg_lock(msqid); | |
679 | if(msq==NULL) | |
680 | return -EINVAL; | |
681 | ||
682 | msg = ERR_PTR(-EIDRM); | |
683 | if (msg_checkid(msq,msqid)) | |
684 | goto out_unlock; | |
685 | ||
686 | for (;;) { | |
687 | struct msg_receiver msr_d; | |
688 | struct list_head* tmp; | |
689 | ||
690 | msg = ERR_PTR(-EACCES); | |
691 | if (ipcperms (&msq->q_perm, S_IRUGO)) | |
692 | goto out_unlock; | |
693 | ||
694 | msg = ERR_PTR(-EAGAIN); | |
695 | tmp = msq->q_messages.next; | |
696 | while (tmp != &msq->q_messages) { | |
697 | struct msg_msg *walk_msg; | |
698 | walk_msg = list_entry(tmp,struct msg_msg,m_list); | |
699 | if(testmsg(walk_msg,msgtyp,mode) && | |
700 | !security_msg_queue_msgrcv(msq, walk_msg, current, msgtyp, mode)) { | |
701 | msg = walk_msg; | |
702 | if(mode == SEARCH_LESSEQUAL && walk_msg->m_type != 1) { | |
703 | msg=walk_msg; | |
704 | msgtyp=walk_msg->m_type-1; | |
705 | } else { | |
706 | msg=walk_msg; | |
707 | break; | |
708 | } | |
709 | } | |
710 | tmp = tmp->next; | |
711 | } | |
712 | if(!IS_ERR(msg)) { | |
713 | /* Found a suitable message. Unlink it from the queue. */ | |
714 | if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { | |
715 | msg = ERR_PTR(-E2BIG); | |
716 | goto out_unlock; | |
717 | } | |
718 | list_del(&msg->m_list); | |
719 | msq->q_qnum--; | |
720 | msq->q_rtime = get_seconds(); | |
721 | msq->q_lrpid = current->tgid; | |
722 | msq->q_cbytes -= msg->m_ts; | |
723 | atomic_sub(msg->m_ts,&msg_bytes); | |
724 | atomic_dec(&msg_hdrs); | |
725 | ss_wakeup(&msq->q_senders,0); | |
726 | msg_unlock(msq); | |
727 | break; | |
728 | } | |
729 | /* No message waiting. Wait for a message */ | |
730 | if (msgflg & IPC_NOWAIT) { | |
731 | msg = ERR_PTR(-ENOMSG); | |
732 | goto out_unlock; | |
733 | } | |
734 | list_add_tail(&msr_d.r_list,&msq->q_receivers); | |
735 | msr_d.r_tsk = current; | |
736 | msr_d.r_msgtype = msgtyp; | |
737 | msr_d.r_mode = mode; | |
738 | if(msgflg & MSG_NOERROR) | |
739 | msr_d.r_maxsize = INT_MAX; | |
740 | else | |
741 | msr_d.r_maxsize = msgsz; | |
742 | msr_d.r_msg = ERR_PTR(-EAGAIN); | |
743 | current->state = TASK_INTERRUPTIBLE; | |
744 | msg_unlock(msq); | |
745 | ||
746 | schedule(); | |
747 | ||
748 | /* Lockless receive, part 1: | |
749 | * Disable preemption. We don't hold a reference to the queue | |
750 | * and getting a reference would defeat the idea of a lockless | |
751 | * operation, thus the code relies on rcu to guarantee the | |
752 | * existance of msq: | |
753 | * Prior to destruction, expunge_all(-EIRDM) changes r_msg. | |
754 | * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. | |
755 | * rcu_read_lock() prevents preemption between reading r_msg | |
756 | * and the spin_lock() inside ipc_lock_by_ptr(). | |
757 | */ | |
758 | rcu_read_lock(); | |
759 | ||
760 | /* Lockless receive, part 2: | |
761 | * Wait until pipelined_send or expunge_all are outside of | |
762 | * wake_up_process(). There is a race with exit(), see | |
763 | * ipc/mqueue.c for the details. | |
764 | */ | |
765 | msg = (struct msg_msg*) msr_d.r_msg; | |
766 | while (msg == NULL) { | |
767 | cpu_relax(); | |
768 | msg = (struct msg_msg*) msr_d.r_msg; | |
769 | } | |
770 | ||
771 | /* Lockless receive, part 3: | |
772 | * If there is a message or an error then accept it without | |
773 | * locking. | |
774 | */ | |
775 | if(msg != ERR_PTR(-EAGAIN)) { | |
776 | rcu_read_unlock(); | |
777 | break; | |
778 | } | |
779 | ||
780 | /* Lockless receive, part 3: | |
781 | * Acquire the queue spinlock. | |
782 | */ | |
783 | ipc_lock_by_ptr(&msq->q_perm); | |
784 | rcu_read_unlock(); | |
785 | ||
786 | /* Lockless receive, part 4: | |
787 | * Repeat test after acquiring the spinlock. | |
788 | */ | |
789 | msg = (struct msg_msg*)msr_d.r_msg; | |
790 | if(msg != ERR_PTR(-EAGAIN)) | |
791 | goto out_unlock; | |
792 | ||
793 | list_del(&msr_d.r_list); | |
794 | if (signal_pending(current)) { | |
795 | msg = ERR_PTR(-ERESTARTNOHAND); | |
796 | out_unlock: | |
797 | msg_unlock(msq); | |
798 | break; | |
799 | } | |
800 | } | |
801 | if (IS_ERR(msg)) | |
802 | return PTR_ERR(msg); | |
803 | ||
804 | msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz; | |
805 | if (put_user (msg->m_type, &msgp->mtype) || | |
806 | store_msg(msgp->mtext, msg, msgsz)) { | |
807 | msgsz = -EFAULT; | |
808 | } | |
809 | free_msg(msg); | |
810 | return msgsz; | |
811 | } | |
812 | ||
813 | #ifdef CONFIG_PROC_FS | |
19b4946c | 814 | static int sysvipc_msg_proc_show(struct seq_file *s, void *it) |
1da177e4 | 815 | { |
19b4946c MW |
816 | struct msg_queue *msq = it; |
817 | ||
818 | return seq_printf(s, | |
819 | "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n", | |
820 | msq->q_perm.key, | |
821 | msq->q_id, | |
822 | msq->q_perm.mode, | |
823 | msq->q_cbytes, | |
824 | msq->q_qnum, | |
825 | msq->q_lspid, | |
826 | msq->q_lrpid, | |
827 | msq->q_perm.uid, | |
828 | msq->q_perm.gid, | |
829 | msq->q_perm.cuid, | |
830 | msq->q_perm.cgid, | |
831 | msq->q_stime, | |
832 | msq->q_rtime, | |
833 | msq->q_ctime); | |
1da177e4 LT |
834 | } |
835 | #endif |