Commit | Line | Data |
---|---|---|
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 | |
15 | * (c) 1999 Manfred Spraul <manfreds@colorfullife.com> | |
16 | */ | |
17 | ||
18 | #include <linux/config.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/msg.h> | |
21 | #include <linux/spinlock.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/proc_fs.h> | |
24 | #include <linux/list.h> | |
25 | #include <linux/security.h> | |
26 | #include <linux/sched.h> | |
27 | #include <linux/syscalls.h> | |
28 | #include <linux/audit.h> | |
29 | #include <asm/current.h> | |
30 | #include <asm/uaccess.h> | |
31 | #include "util.h" | |
32 | ||
33 | /* sysctl: */ | |
34 | int msg_ctlmax = MSGMAX; | |
35 | int msg_ctlmnb = MSGMNB; | |
36 | int msg_ctlmni = MSGMNI; | |
37 | ||
38 | /* one msg_receiver structure for each sleeping receiver */ | |
39 | struct msg_receiver { | |
40 | struct list_head r_list; | |
41 | struct task_struct* r_tsk; | |
42 | ||
43 | int r_mode; | |
44 | long r_msgtype; | |
45 | long r_maxsize; | |
46 | ||
47 | struct msg_msg* volatile r_msg; | |
48 | }; | |
49 | ||
50 | /* one msg_sender for each sleeping sender */ | |
51 | struct msg_sender { | |
52 | struct list_head list; | |
53 | struct task_struct* tsk; | |
54 | }; | |
55 | ||
56 | #define SEARCH_ANY 1 | |
57 | #define SEARCH_EQUAL 2 | |
58 | #define SEARCH_NOTEQUAL 3 | |
59 | #define SEARCH_LESSEQUAL 4 | |
60 | ||
61 | static atomic_t msg_bytes = ATOMIC_INIT(0); | |
62 | static atomic_t msg_hdrs = ATOMIC_INIT(0); | |
63 | ||
64 | static struct ipc_ids msg_ids; | |
65 | ||
66 | #define msg_lock(id) ((struct msg_queue*)ipc_lock(&msg_ids,id)) | |
67 | #define msg_unlock(msq) ipc_unlock(&(msq)->q_perm) | |
68 | #define msg_rmid(id) ((struct msg_queue*)ipc_rmid(&msg_ids,id)) | |
69 | #define msg_checkid(msq, msgid) \ | |
70 | ipc_checkid(&msg_ids,&msq->q_perm,msgid) | |
71 | #define msg_buildid(id, seq) \ | |
72 | ipc_buildid(&msg_ids, id, seq) | |
73 | ||
74 | static void freeque (struct msg_queue *msq, int id); | |
75 | static int newque (key_t key, int msgflg); | |
76 | #ifdef CONFIG_PROC_FS | |
77 | static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data); | |
78 | #endif | |
79 | ||
80 | void __init msg_init (void) | |
81 | { | |
82 | ipc_init_ids(&msg_ids,msg_ctlmni); | |
83 | ||
84 | #ifdef CONFIG_PROC_FS | |
85 | create_proc_read_entry("sysvipc/msg", 0, NULL, sysvipc_msg_read_proc, NULL); | |
86 | #endif | |
87 | } | |
88 | ||
89 | static int newque (key_t key, int msgflg) | |
90 | { | |
91 | int id; | |
92 | int retval; | |
93 | struct msg_queue *msq; | |
94 | ||
95 | msq = ipc_rcu_alloc(sizeof(*msq)); | |
96 | if (!msq) | |
97 | return -ENOMEM; | |
98 | ||
99 | msq->q_perm.mode = (msgflg & S_IRWXUGO); | |
100 | msq->q_perm.key = key; | |
101 | ||
102 | msq->q_perm.security = NULL; | |
103 | retval = security_msg_queue_alloc(msq); | |
104 | if (retval) { | |
105 | ipc_rcu_putref(msq); | |
106 | return retval; | |
107 | } | |
108 | ||
109 | id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni); | |
110 | if(id == -1) { | |
111 | security_msg_queue_free(msq); | |
112 | ipc_rcu_putref(msq); | |
113 | return -ENOSPC; | |
114 | } | |
115 | ||
116 | msq->q_stime = msq->q_rtime = 0; | |
117 | msq->q_ctime = get_seconds(); | |
118 | msq->q_cbytes = msq->q_qnum = 0; | |
119 | msq->q_qbytes = msg_ctlmnb; | |
120 | msq->q_lspid = msq->q_lrpid = 0; | |
121 | INIT_LIST_HEAD(&msq->q_messages); | |
122 | INIT_LIST_HEAD(&msq->q_receivers); | |
123 | INIT_LIST_HEAD(&msq->q_senders); | |
124 | msg_unlock(msq); | |
125 | ||
126 | return msg_buildid(id,msq->q_perm.seq); | |
127 | } | |
128 | ||
129 | static inline void ss_add(struct msg_queue* msq, struct msg_sender* mss) | |
130 | { | |
131 | mss->tsk=current; | |
132 | current->state=TASK_INTERRUPTIBLE; | |
133 | list_add_tail(&mss->list,&msq->q_senders); | |
134 | } | |
135 | ||
136 | static inline void ss_del(struct msg_sender* mss) | |
137 | { | |
138 | if(mss->list.next != NULL) | |
139 | list_del(&mss->list); | |
140 | } | |
141 | ||
142 | static void ss_wakeup(struct list_head* h, int kill) | |
143 | { | |
144 | struct list_head *tmp; | |
145 | ||
146 | tmp = h->next; | |
147 | while (tmp != h) { | |
148 | struct msg_sender* mss; | |
149 | ||
150 | mss = list_entry(tmp,struct msg_sender,list); | |
151 | tmp = tmp->next; | |
152 | if(kill) | |
153 | mss->list.next=NULL; | |
154 | wake_up_process(mss->tsk); | |
155 | } | |
156 | } | |
157 | ||
158 | static void expunge_all(struct msg_queue* msq, int res) | |
159 | { | |
160 | struct list_head *tmp; | |
161 | ||
162 | tmp = msq->q_receivers.next; | |
163 | while (tmp != &msq->q_receivers) { | |
164 | struct msg_receiver* msr; | |
165 | ||
166 | msr = list_entry(tmp,struct msg_receiver,r_list); | |
167 | tmp = tmp->next; | |
168 | msr->r_msg = NULL; | |
169 | wake_up_process(msr->r_tsk); | |
170 | smp_mb(); | |
171 | msr->r_msg = ERR_PTR(res); | |
172 | } | |
173 | } | |
174 | /* | |
175 | * freeque() wakes up waiters on the sender and receiver waiting queue, | |
176 | * removes the message queue from message queue ID | |
177 | * array, and cleans up all the messages associated with this queue. | |
178 | * | |
179 | * msg_ids.sem and the spinlock for this message queue is hold | |
180 | * before freeque() is called. msg_ids.sem remains locked on exit. | |
181 | */ | |
182 | static void freeque (struct msg_queue *msq, int id) | |
183 | { | |
184 | struct list_head *tmp; | |
185 | ||
186 | expunge_all(msq,-EIDRM); | |
187 | ss_wakeup(&msq->q_senders,1); | |
188 | msq = msg_rmid(id); | |
189 | msg_unlock(msq); | |
190 | ||
191 | tmp = msq->q_messages.next; | |
192 | while(tmp != &msq->q_messages) { | |
193 | struct msg_msg* msg = list_entry(tmp,struct msg_msg,m_list); | |
194 | tmp = tmp->next; | |
195 | atomic_dec(&msg_hdrs); | |
196 | free_msg(msg); | |
197 | } | |
198 | atomic_sub(msq->q_cbytes, &msg_bytes); | |
199 | security_msg_queue_free(msq); | |
200 | ipc_rcu_putref(msq); | |
201 | } | |
202 | ||
203 | asmlinkage long sys_msgget (key_t key, int msgflg) | |
204 | { | |
205 | int id, ret = -EPERM; | |
206 | struct msg_queue *msq; | |
207 | ||
208 | down(&msg_ids.sem); | |
209 | if (key == IPC_PRIVATE) | |
210 | ret = newque(key, msgflg); | |
211 | else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */ | |
212 | if (!(msgflg & IPC_CREAT)) | |
213 | ret = -ENOENT; | |
214 | else | |
215 | ret = newque(key, msgflg); | |
216 | } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) { | |
217 | ret = -EEXIST; | |
218 | } else { | |
219 | msq = msg_lock(id); | |
220 | if(msq==NULL) | |
221 | BUG(); | |
222 | if (ipcperms(&msq->q_perm, msgflg)) | |
223 | ret = -EACCES; | |
224 | else { | |
225 | int qid = msg_buildid(id, msq->q_perm.seq); | |
226 | ret = security_msg_queue_associate(msq, msgflg); | |
227 | if (!ret) | |
228 | ret = qid; | |
229 | } | |
230 | msg_unlock(msq); | |
231 | } | |
232 | up(&msg_ids.sem); | |
233 | return ret; | |
234 | } | |
235 | ||
236 | static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) | |
237 | { | |
238 | switch(version) { | |
239 | case IPC_64: | |
240 | return copy_to_user (buf, in, sizeof(*in)); | |
241 | case IPC_OLD: | |
242 | { | |
243 | struct msqid_ds out; | |
244 | ||
245 | memset(&out,0,sizeof(out)); | |
246 | ||
247 | ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); | |
248 | ||
249 | out.msg_stime = in->msg_stime; | |
250 | out.msg_rtime = in->msg_rtime; | |
251 | out.msg_ctime = in->msg_ctime; | |
252 | ||
253 | if(in->msg_cbytes > USHRT_MAX) | |
254 | out.msg_cbytes = USHRT_MAX; | |
255 | else | |
256 | out.msg_cbytes = in->msg_cbytes; | |
257 | out.msg_lcbytes = in->msg_cbytes; | |
258 | ||
259 | if(in->msg_qnum > USHRT_MAX) | |
260 | out.msg_qnum = USHRT_MAX; | |
261 | else | |
262 | out.msg_qnum = in->msg_qnum; | |
263 | ||
264 | if(in->msg_qbytes > USHRT_MAX) | |
265 | out.msg_qbytes = USHRT_MAX; | |
266 | else | |
267 | out.msg_qbytes = in->msg_qbytes; | |
268 | out.msg_lqbytes = in->msg_qbytes; | |
269 | ||
270 | out.msg_lspid = in->msg_lspid; | |
271 | out.msg_lrpid = in->msg_lrpid; | |
272 | ||
273 | return copy_to_user (buf, &out, sizeof(out)); | |
274 | } | |
275 | default: | |
276 | return -EINVAL; | |
277 | } | |
278 | } | |
279 | ||
280 | struct msq_setbuf { | |
281 | unsigned long qbytes; | |
282 | uid_t uid; | |
283 | gid_t gid; | |
284 | mode_t mode; | |
285 | }; | |
286 | ||
287 | static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version) | |
288 | { | |
289 | switch(version) { | |
290 | case IPC_64: | |
291 | { | |
292 | struct msqid64_ds tbuf; | |
293 | ||
294 | if (copy_from_user (&tbuf, buf, sizeof (tbuf))) | |
295 | return -EFAULT; | |
296 | ||
297 | out->qbytes = tbuf.msg_qbytes; | |
298 | out->uid = tbuf.msg_perm.uid; | |
299 | out->gid = tbuf.msg_perm.gid; | |
300 | out->mode = tbuf.msg_perm.mode; | |
301 | ||
302 | return 0; | |
303 | } | |
304 | case IPC_OLD: | |
305 | { | |
306 | struct msqid_ds tbuf_old; | |
307 | ||
308 | if (copy_from_user (&tbuf_old, buf, sizeof (tbuf_old))) | |
309 | return -EFAULT; | |
310 | ||
311 | out->uid = tbuf_old.msg_perm.uid; | |
312 | out->gid = tbuf_old.msg_perm.gid; | |
313 | out->mode = tbuf_old.msg_perm.mode; | |
314 | ||
315 | if(tbuf_old.msg_qbytes == 0) | |
316 | out->qbytes = tbuf_old.msg_lqbytes; | |
317 | else | |
318 | out->qbytes = tbuf_old.msg_qbytes; | |
319 | ||
320 | return 0; | |
321 | } | |
322 | default: | |
323 | return -EINVAL; | |
324 | } | |
325 | } | |
326 | ||
327 | asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds __user *buf) | |
328 | { | |
329 | int err, version; | |
330 | struct msg_queue *msq; | |
331 | struct msq_setbuf setbuf; | |
332 | struct kern_ipc_perm *ipcp; | |
333 | ||
334 | if (msqid < 0 || cmd < 0) | |
335 | return -EINVAL; | |
336 | ||
337 | version = ipc_parse_version(&cmd); | |
338 | ||
339 | switch (cmd) { | |
340 | case IPC_INFO: | |
341 | case MSG_INFO: | |
342 | { | |
343 | struct msginfo msginfo; | |
344 | int max_id; | |
345 | if (!buf) | |
346 | return -EFAULT; | |
347 | /* We must not return kernel stack data. | |
348 | * due to padding, it's not enough | |
349 | * to set all member fields. | |
350 | */ | |
351 | ||
352 | err = security_msg_queue_msgctl(NULL, cmd); | |
353 | if (err) | |
354 | return err; | |
355 | ||
356 | memset(&msginfo,0,sizeof(msginfo)); | |
357 | msginfo.msgmni = msg_ctlmni; | |
358 | msginfo.msgmax = msg_ctlmax; | |
359 | msginfo.msgmnb = msg_ctlmnb; | |
360 | msginfo.msgssz = MSGSSZ; | |
361 | msginfo.msgseg = MSGSEG; | |
362 | down(&msg_ids.sem); | |
363 | if (cmd == MSG_INFO) { | |
364 | msginfo.msgpool = msg_ids.in_use; | |
365 | msginfo.msgmap = atomic_read(&msg_hdrs); | |
366 | msginfo.msgtql = atomic_read(&msg_bytes); | |
367 | } else { | |
368 | msginfo.msgmap = MSGMAP; | |
369 | msginfo.msgpool = MSGPOOL; | |
370 | msginfo.msgtql = MSGTQL; | |
371 | } | |
372 | max_id = msg_ids.max_id; | |
373 | up(&msg_ids.sem); | |
374 | if (copy_to_user (buf, &msginfo, sizeof(struct msginfo))) | |
375 | return -EFAULT; | |
376 | return (max_id < 0) ? 0: max_id; | |
377 | } | |
378 | case MSG_STAT: | |
379 | case IPC_STAT: | |
380 | { | |
381 | struct msqid64_ds tbuf; | |
382 | int success_return; | |
383 | if (!buf) | |
384 | return -EFAULT; | |
385 | if(cmd == MSG_STAT && msqid >= msg_ids.entries->size) | |
386 | return -EINVAL; | |
387 | ||
388 | memset(&tbuf,0,sizeof(tbuf)); | |
389 | ||
390 | msq = msg_lock(msqid); | |
391 | if (msq == NULL) | |
392 | return -EINVAL; | |
393 | ||
394 | if(cmd == MSG_STAT) { | |
395 | success_return = msg_buildid(msqid, msq->q_perm.seq); | |
396 | } else { | |
397 | err = -EIDRM; | |
398 | if (msg_checkid(msq,msqid)) | |
399 | goto out_unlock; | |
400 | success_return = 0; | |
401 | } | |
402 | err = -EACCES; | |
403 | if (ipcperms (&msq->q_perm, S_IRUGO)) | |
404 | goto out_unlock; | |
405 | ||
406 | err = security_msg_queue_msgctl(msq, cmd); | |
407 | if (err) | |
408 | goto out_unlock; | |
409 | ||
410 | kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); | |
411 | tbuf.msg_stime = msq->q_stime; | |
412 | tbuf.msg_rtime = msq->q_rtime; | |
413 | tbuf.msg_ctime = msq->q_ctime; | |
414 | tbuf.msg_cbytes = msq->q_cbytes; | |
415 | tbuf.msg_qnum = msq->q_qnum; | |
416 | tbuf.msg_qbytes = msq->q_qbytes; | |
417 | tbuf.msg_lspid = msq->q_lspid; | |
418 | tbuf.msg_lrpid = msq->q_lrpid; | |
419 | msg_unlock(msq); | |
420 | if (copy_msqid_to_user(buf, &tbuf, version)) | |
421 | return -EFAULT; | |
422 | return success_return; | |
423 | } | |
424 | case IPC_SET: | |
425 | if (!buf) | |
426 | return -EFAULT; | |
427 | if (copy_msqid_from_user (&setbuf, buf, version)) | |
428 | return -EFAULT; | |
429 | if ((err = audit_ipc_perms(setbuf.qbytes, setbuf.uid, setbuf.gid, setbuf.mode))) | |
430 | return err; | |
431 | break; | |
432 | case IPC_RMID: | |
433 | break; | |
434 | default: | |
435 | return -EINVAL; | |
436 | } | |
437 | ||
438 | down(&msg_ids.sem); | |
439 | msq = msg_lock(msqid); | |
440 | err=-EINVAL; | |
441 | if (msq == NULL) | |
442 | goto out_up; | |
443 | ||
444 | err = -EIDRM; | |
445 | if (msg_checkid(msq,msqid)) | |
446 | goto out_unlock_up; | |
447 | ipcp = &msq->q_perm; | |
448 | err = -EPERM; | |
449 | if (current->euid != ipcp->cuid && | |
450 | current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) | |
451 | /* We _could_ check for CAP_CHOWN above, but we don't */ | |
452 | goto out_unlock_up; | |
453 | ||
454 | err = security_msg_queue_msgctl(msq, cmd); | |
455 | if (err) | |
456 | goto out_unlock_up; | |
457 | ||
458 | switch (cmd) { | |
459 | case IPC_SET: | |
460 | { | |
461 | err = -EPERM; | |
462 | if (setbuf.qbytes > msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) | |
463 | goto out_unlock_up; | |
464 | ||
465 | msq->q_qbytes = setbuf.qbytes; | |
466 | ||
467 | ipcp->uid = setbuf.uid; | |
468 | ipcp->gid = setbuf.gid; | |
469 | ipcp->mode = (ipcp->mode & ~S_IRWXUGO) | | |
470 | (S_IRWXUGO & setbuf.mode); | |
471 | msq->q_ctime = get_seconds(); | |
472 | /* sleeping receivers might be excluded by | |
473 | * stricter permissions. | |
474 | */ | |
475 | expunge_all(msq,-EAGAIN); | |
476 | /* sleeping senders might be able to send | |
477 | * due to a larger queue size. | |
478 | */ | |
479 | ss_wakeup(&msq->q_senders,0); | |
480 | msg_unlock(msq); | |
481 | break; | |
482 | } | |
483 | case IPC_RMID: | |
484 | freeque (msq, msqid); | |
485 | break; | |
486 | } | |
487 | err = 0; | |
488 | out_up: | |
489 | up(&msg_ids.sem); | |
490 | return err; | |
491 | out_unlock_up: | |
492 | msg_unlock(msq); | |
493 | goto out_up; | |
494 | out_unlock: | |
495 | msg_unlock(msq); | |
496 | return err; | |
497 | } | |
498 | ||
499 | static int testmsg(struct msg_msg* msg,long type,int mode) | |
500 | { | |
501 | switch(mode) | |
502 | { | |
503 | case SEARCH_ANY: | |
504 | return 1; | |
505 | case SEARCH_LESSEQUAL: | |
506 | if(msg->m_type <=type) | |
507 | return 1; | |
508 | break; | |
509 | case SEARCH_EQUAL: | |
510 | if(msg->m_type == type) | |
511 | return 1; | |
512 | break; | |
513 | case SEARCH_NOTEQUAL: | |
514 | if(msg->m_type != type) | |
515 | return 1; | |
516 | break; | |
517 | } | |
518 | return 0; | |
519 | } | |
520 | ||
521 | static inline int pipelined_send(struct msg_queue* msq, struct msg_msg* msg) | |
522 | { | |
523 | struct list_head* tmp; | |
524 | ||
525 | tmp = msq->q_receivers.next; | |
526 | while (tmp != &msq->q_receivers) { | |
527 | struct msg_receiver* msr; | |
528 | msr = list_entry(tmp,struct msg_receiver,r_list); | |
529 | tmp = tmp->next; | |
530 | if(testmsg(msg,msr->r_msgtype,msr->r_mode) && | |
531 | !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, msr->r_msgtype, msr->r_mode)) { | |
532 | list_del(&msr->r_list); | |
533 | if(msr->r_maxsize < msg->m_ts) { | |
534 | msr->r_msg = NULL; | |
535 | wake_up_process(msr->r_tsk); | |
536 | smp_mb(); | |
537 | msr->r_msg = ERR_PTR(-E2BIG); | |
538 | } else { | |
539 | msr->r_msg = NULL; | |
540 | msq->q_lrpid = msr->r_tsk->pid; | |
541 | msq->q_rtime = get_seconds(); | |
542 | wake_up_process(msr->r_tsk); | |
543 | smp_mb(); | |
544 | msr->r_msg = msg; | |
545 | return 1; | |
546 | } | |
547 | } | |
548 | } | |
549 | return 0; | |
550 | } | |
551 | ||
552 | asmlinkage long sys_msgsnd (int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg) | |
553 | { | |
554 | struct msg_queue *msq; | |
555 | struct msg_msg *msg; | |
556 | long mtype; | |
557 | int err; | |
558 | ||
559 | if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0) | |
560 | return -EINVAL; | |
561 | if (get_user(mtype, &msgp->mtype)) | |
562 | return -EFAULT; | |
563 | if (mtype < 1) | |
564 | return -EINVAL; | |
565 | ||
566 | msg = load_msg(msgp->mtext, msgsz); | |
567 | if(IS_ERR(msg)) | |
568 | return PTR_ERR(msg); | |
569 | ||
570 | msg->m_type = mtype; | |
571 | msg->m_ts = msgsz; | |
572 | ||
573 | msq = msg_lock(msqid); | |
574 | err=-EINVAL; | |
575 | if(msq==NULL) | |
576 | goto out_free; | |
577 | ||
578 | err= -EIDRM; | |
579 | if (msg_checkid(msq,msqid)) | |
580 | goto out_unlock_free; | |
581 | ||
582 | for (;;) { | |
583 | struct msg_sender s; | |
584 | ||
585 | err=-EACCES; | |
586 | if (ipcperms(&msq->q_perm, S_IWUGO)) | |
587 | goto out_unlock_free; | |
588 | ||
589 | err = security_msg_queue_msgsnd(msq, msg, msgflg); | |
590 | if (err) | |
591 | goto out_unlock_free; | |
592 | ||
593 | if(msgsz + msq->q_cbytes <= msq->q_qbytes && | |
594 | 1 + msq->q_qnum <= msq->q_qbytes) { | |
595 | break; | |
596 | } | |
597 | ||
598 | /* queue full, wait: */ | |
599 | if(msgflg&IPC_NOWAIT) { | |
600 | err=-EAGAIN; | |
601 | goto out_unlock_free; | |
602 | } | |
603 | ss_add(msq, &s); | |
604 | ipc_rcu_getref(msq); | |
605 | msg_unlock(msq); | |
606 | schedule(); | |
607 | ||
608 | ipc_lock_by_ptr(&msq->q_perm); | |
609 | ipc_rcu_putref(msq); | |
610 | if (msq->q_perm.deleted) { | |
611 | err = -EIDRM; | |
612 | goto out_unlock_free; | |
613 | } | |
614 | ss_del(&s); | |
615 | ||
616 | if (signal_pending(current)) { | |
617 | err=-ERESTARTNOHAND; | |
618 | goto out_unlock_free; | |
619 | } | |
620 | } | |
621 | ||
622 | msq->q_lspid = current->tgid; | |
623 | msq->q_stime = get_seconds(); | |
624 | ||
625 | if(!pipelined_send(msq,msg)) { | |
626 | /* noone is waiting for this message, enqueue it */ | |
627 | list_add_tail(&msg->m_list,&msq->q_messages); | |
628 | msq->q_cbytes += msgsz; | |
629 | msq->q_qnum++; | |
630 | atomic_add(msgsz,&msg_bytes); | |
631 | atomic_inc(&msg_hdrs); | |
632 | } | |
633 | ||
634 | err = 0; | |
635 | msg = NULL; | |
636 | ||
637 | out_unlock_free: | |
638 | msg_unlock(msq); | |
639 | out_free: | |
640 | if(msg!=NULL) | |
641 | free_msg(msg); | |
642 | return err; | |
643 | } | |
644 | ||
645 | static inline int convert_mode(long* msgtyp, int msgflg) | |
646 | { | |
647 | /* | |
648 | * find message of correct type. | |
649 | * msgtyp = 0 => get first. | |
650 | * msgtyp > 0 => get first message of matching type. | |
651 | * msgtyp < 0 => get message with least type must be < abs(msgtype). | |
652 | */ | |
653 | if(*msgtyp==0) | |
654 | return SEARCH_ANY; | |
655 | if(*msgtyp<0) { | |
656 | *msgtyp=-(*msgtyp); | |
657 | return SEARCH_LESSEQUAL; | |
658 | } | |
659 | if(msgflg & MSG_EXCEPT) | |
660 | return SEARCH_NOTEQUAL; | |
661 | return SEARCH_EQUAL; | |
662 | } | |
663 | ||
664 | asmlinkage long sys_msgrcv (int msqid, struct msgbuf __user *msgp, size_t msgsz, | |
665 | long msgtyp, int msgflg) | |
666 | { | |
667 | struct msg_queue *msq; | |
668 | struct msg_msg *msg; | |
669 | int mode; | |
670 | ||
671 | if (msqid < 0 || (long) msgsz < 0) | |
672 | return -EINVAL; | |
673 | mode = convert_mode(&msgtyp,msgflg); | |
674 | ||
675 | msq = msg_lock(msqid); | |
676 | if(msq==NULL) | |
677 | return -EINVAL; | |
678 | ||
679 | msg = ERR_PTR(-EIDRM); | |
680 | if (msg_checkid(msq,msqid)) | |
681 | goto out_unlock; | |
682 | ||
683 | for (;;) { | |
684 | struct msg_receiver msr_d; | |
685 | struct list_head* tmp; | |
686 | ||
687 | msg = ERR_PTR(-EACCES); | |
688 | if (ipcperms (&msq->q_perm, S_IRUGO)) | |
689 | goto out_unlock; | |
690 | ||
691 | msg = ERR_PTR(-EAGAIN); | |
692 | tmp = msq->q_messages.next; | |
693 | while (tmp != &msq->q_messages) { | |
694 | struct msg_msg *walk_msg; | |
695 | walk_msg = list_entry(tmp,struct msg_msg,m_list); | |
696 | if(testmsg(walk_msg,msgtyp,mode) && | |
697 | !security_msg_queue_msgrcv(msq, walk_msg, current, msgtyp, mode)) { | |
698 | msg = walk_msg; | |
699 | if(mode == SEARCH_LESSEQUAL && walk_msg->m_type != 1) { | |
700 | msg=walk_msg; | |
701 | msgtyp=walk_msg->m_type-1; | |
702 | } else { | |
703 | msg=walk_msg; | |
704 | break; | |
705 | } | |
706 | } | |
707 | tmp = tmp->next; | |
708 | } | |
709 | if(!IS_ERR(msg)) { | |
710 | /* Found a suitable message. Unlink it from the queue. */ | |
711 | if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { | |
712 | msg = ERR_PTR(-E2BIG); | |
713 | goto out_unlock; | |
714 | } | |
715 | list_del(&msg->m_list); | |
716 | msq->q_qnum--; | |
717 | msq->q_rtime = get_seconds(); | |
718 | msq->q_lrpid = current->tgid; | |
719 | msq->q_cbytes -= msg->m_ts; | |
720 | atomic_sub(msg->m_ts,&msg_bytes); | |
721 | atomic_dec(&msg_hdrs); | |
722 | ss_wakeup(&msq->q_senders,0); | |
723 | msg_unlock(msq); | |
724 | break; | |
725 | } | |
726 | /* No message waiting. Wait for a message */ | |
727 | if (msgflg & IPC_NOWAIT) { | |
728 | msg = ERR_PTR(-ENOMSG); | |
729 | goto out_unlock; | |
730 | } | |
731 | list_add_tail(&msr_d.r_list,&msq->q_receivers); | |
732 | msr_d.r_tsk = current; | |
733 | msr_d.r_msgtype = msgtyp; | |
734 | msr_d.r_mode = mode; | |
735 | if(msgflg & MSG_NOERROR) | |
736 | msr_d.r_maxsize = INT_MAX; | |
737 | else | |
738 | msr_d.r_maxsize = msgsz; | |
739 | msr_d.r_msg = ERR_PTR(-EAGAIN); | |
740 | current->state = TASK_INTERRUPTIBLE; | |
741 | msg_unlock(msq); | |
742 | ||
743 | schedule(); | |
744 | ||
745 | /* Lockless receive, part 1: | |
746 | * Disable preemption. We don't hold a reference to the queue | |
747 | * and getting a reference would defeat the idea of a lockless | |
748 | * operation, thus the code relies on rcu to guarantee the | |
749 | * existance of msq: | |
750 | * Prior to destruction, expunge_all(-EIRDM) changes r_msg. | |
751 | * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. | |
752 | * rcu_read_lock() prevents preemption between reading r_msg | |
753 | * and the spin_lock() inside ipc_lock_by_ptr(). | |
754 | */ | |
755 | rcu_read_lock(); | |
756 | ||
757 | /* Lockless receive, part 2: | |
758 | * Wait until pipelined_send or expunge_all are outside of | |
759 | * wake_up_process(). There is a race with exit(), see | |
760 | * ipc/mqueue.c for the details. | |
761 | */ | |
762 | msg = (struct msg_msg*) msr_d.r_msg; | |
763 | while (msg == NULL) { | |
764 | cpu_relax(); | |
765 | msg = (struct msg_msg*) msr_d.r_msg; | |
766 | } | |
767 | ||
768 | /* Lockless receive, part 3: | |
769 | * If there is a message or an error then accept it without | |
770 | * locking. | |
771 | */ | |
772 | if(msg != ERR_PTR(-EAGAIN)) { | |
773 | rcu_read_unlock(); | |
774 | break; | |
775 | } | |
776 | ||
777 | /* Lockless receive, part 3: | |
778 | * Acquire the queue spinlock. | |
779 | */ | |
780 | ipc_lock_by_ptr(&msq->q_perm); | |
781 | rcu_read_unlock(); | |
782 | ||
783 | /* Lockless receive, part 4: | |
784 | * Repeat test after acquiring the spinlock. | |
785 | */ | |
786 | msg = (struct msg_msg*)msr_d.r_msg; | |
787 | if(msg != ERR_PTR(-EAGAIN)) | |
788 | goto out_unlock; | |
789 | ||
790 | list_del(&msr_d.r_list); | |
791 | if (signal_pending(current)) { | |
792 | msg = ERR_PTR(-ERESTARTNOHAND); | |
793 | out_unlock: | |
794 | msg_unlock(msq); | |
795 | break; | |
796 | } | |
797 | } | |
798 | if (IS_ERR(msg)) | |
799 | return PTR_ERR(msg); | |
800 | ||
801 | msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz; | |
802 | if (put_user (msg->m_type, &msgp->mtype) || | |
803 | store_msg(msgp->mtext, msg, msgsz)) { | |
804 | msgsz = -EFAULT; | |
805 | } | |
806 | free_msg(msg); | |
807 | return msgsz; | |
808 | } | |
809 | ||
810 | #ifdef CONFIG_PROC_FS | |
811 | static int sysvipc_msg_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data) | |
812 | { | |
813 | off_t pos = 0; | |
814 | off_t begin = 0; | |
815 | int i, len = 0; | |
816 | ||
817 | down(&msg_ids.sem); | |
818 | len += sprintf(buffer, " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n"); | |
819 | ||
820 | for(i = 0; i <= msg_ids.max_id; i++) { | |
821 | struct msg_queue * msq; | |
822 | msq = msg_lock(i); | |
823 | if(msq != NULL) { | |
824 | len += sprintf(buffer + len, "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n", | |
825 | msq->q_perm.key, | |
826 | msg_buildid(i,msq->q_perm.seq), | |
827 | msq->q_perm.mode, | |
828 | msq->q_cbytes, | |
829 | msq->q_qnum, | |
830 | msq->q_lspid, | |
831 | msq->q_lrpid, | |
832 | msq->q_perm.uid, | |
833 | msq->q_perm.gid, | |
834 | msq->q_perm.cuid, | |
835 | msq->q_perm.cgid, | |
836 | msq->q_stime, | |
837 | msq->q_rtime, | |
838 | msq->q_ctime); | |
839 | msg_unlock(msq); | |
840 | ||
841 | pos += len; | |
842 | if(pos < offset) { | |
843 | len = 0; | |
844 | begin = pos; | |
845 | } | |
846 | if(pos > offset + length) | |
847 | goto done; | |
848 | } | |
849 | ||
850 | } | |
851 | *eof = 1; | |
852 | done: | |
853 | up(&msg_ids.sem); | |
854 | *start = buffer + (offset - begin); | |
855 | len -= (offset - begin); | |
856 | if(len > length) | |
857 | len = length; | |
858 | if(len < 0) | |
859 | len = 0; | |
860 | return len; | |
861 | } | |
862 | #endif |