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[PATCH] machine_kexec.c: Fix the description of segment handling
[usb.git] / ipc / mqueue.c
blob02e6f679897282d4d16c73ed70ccb9f5e98857e5
1 /*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
5 * Michal Wronski (Michal.Wronski@motorola.com)
6 *
7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com)
8 * Lockless receive & send, fd based notify:
9 * Manfred Spraul (manfred@colorfullife.com)
10 *
11 * Audit: George Wilson (ltcgcw@us.ibm.com)
12 *
13 * This file is released under the GPL.
14 */
15
16 #include <linux/capability.h>
17 #include <linux/init.h>
18 #include <linux/pagemap.h>
19 #include <linux/file.h>
20 #include <linux/mount.h>
21 #include <linux/namei.h>
22 #include <linux/sysctl.h>
23 #include <linux/poll.h>
24 #include <linux/mqueue.h>
25 #include <linux/msg.h>
26 #include <linux/skbuff.h>
27 #include <linux/netlink.h>
28 #include <linux/syscalls.h>
29 #include <linux/audit.h>
30 #include <linux/signal.h>
31 #include <linux/mutex.h>
32
33 #include <net/sock.h>
34 #include "util.h"
35
36 #define MQUEUE_MAGIC 0x19800202
37 #define DIRENT_SIZE 20
38 #define FILENT_SIZE 80
39
40 #define SEND 0
41 #define RECV 1
42
43 #define STATE_NONE 0
44 #define STATE_PENDING 1
45 #define STATE_READY 2
46
47 /* used by sysctl */
48 #define FS_MQUEUE 1
49 #define CTL_QUEUESMAX 2
50 #define CTL_MSGMAX 3
51 #define CTL_MSGSIZEMAX 4
52
53 /* default values */
54 #define DFLT_QUEUESMAX 256 /* max number of message queues */
55 #define DFLT_MSGMAX 10 /* max number of messages in each queue */
56 #define HARD_MSGMAX (131072/sizeof(void*))
57 #define DFLT_MSGSIZEMAX 8192 /* max message size */
58
59
60 struct ext_wait_queue { /* queue of sleeping tasks */
61 struct task_struct *task;
62 struct list_head list;
63 struct msg_msg *msg; /* ptr of loaded message */
64 int state; /* one of STATE_* values */
65 };
66
67 struct mqueue_inode_info {
68 spinlock_t lock;
69 struct inode vfs_inode;
70 wait_queue_head_t wait_q;
71
72 struct msg_msg **messages;
73 struct mq_attr attr;
74
75 struct sigevent notify;
76 pid_t notify_owner;
77 struct user_struct *user; /* user who created, for accounting */
78 struct sock *notify_sock;
79 struct sk_buff *notify_cookie;
80
81 /* for tasks waiting for free space and messages, respectively */
82 struct ext_wait_queue e_wait_q[2];
83
84 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
85 };
86
87 static struct inode_operations mqueue_dir_inode_operations;
88 static struct file_operations mqueue_file_operations;
89 static struct super_operations mqueue_super_ops;
90 static void remove_notification(struct mqueue_inode_info *info);
91
92 static spinlock_t mq_lock;
93 static kmem_cache_t *mqueue_inode_cachep;
94 static struct vfsmount *mqueue_mnt;
95
96 static unsigned int queues_count;
97 static unsigned int queues_max = DFLT_QUEUESMAX;
98 static unsigned int msg_max = DFLT_MSGMAX;
99 static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
100
101 static struct ctl_table_header * mq_sysctl_table;
102
103 static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
104 {
105 return container_of(inode, struct mqueue_inode_info, vfs_inode);
106 }
107
108 static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
109 struct mq_attr *attr)
110 {
111 struct inode *inode;
112
113 inode = new_inode(sb);
114 if (inode) {
115 inode->i_mode = mode;
116 inode->i_uid = current->fsuid;
117 inode->i_gid = current->fsgid;
118 inode->i_blksize = PAGE_CACHE_SIZE;
119 inode->i_blocks = 0;
120 inode->i_mtime = inode->i_ctime = inode->i_atime =
121 CURRENT_TIME;
122
123 if (S_ISREG(mode)) {
124 struct mqueue_inode_info *info;
125 struct task_struct *p = current;
126 struct user_struct *u = p->user;
127 unsigned long mq_bytes, mq_msg_tblsz;
128
129 inode->i_fop = &mqueue_file_operations;
130 inode->i_size = FILENT_SIZE;
131 /* mqueue specific info */
132 info = MQUEUE_I(inode);
133 spin_lock_init(&info->lock);
134 init_waitqueue_head(&info->wait_q);
135 INIT_LIST_HEAD(&info->e_wait_q[0].list);
136 INIT_LIST_HEAD(&info->e_wait_q[1].list);
137 info->messages = NULL;
138 info->notify_owner = 0;
139 info->qsize = 0;
140 info->user = NULL; /* set when all is ok */
141 memset(&info->attr, 0, sizeof(info->attr));
142 info->attr.mq_maxmsg = DFLT_MSGMAX;
143 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
144 if (attr) {
145 info->attr.mq_maxmsg = attr->mq_maxmsg;
146 info->attr.mq_msgsize = attr->mq_msgsize;
147 }
148 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
149 mq_bytes = (mq_msg_tblsz +
150 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
151
152 spin_lock(&mq_lock);
153 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
154 u->mq_bytes + mq_bytes >
155 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
156 spin_unlock(&mq_lock);
157 goto out_inode;
158 }
159 u->mq_bytes += mq_bytes;
160 spin_unlock(&mq_lock);
161
162 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
163 if (!info->messages) {
164 spin_lock(&mq_lock);
165 u->mq_bytes -= mq_bytes;
166 spin_unlock(&mq_lock);
167 goto out_inode;
168 }
169 /* all is ok */
170 info->user = get_uid(u);
171 } else if (S_ISDIR(mode)) {
172 inode->i_nlink++;
173 /* Some things misbehave if size == 0 on a directory */
174 inode->i_size = 2 * DIRENT_SIZE;
175 inode->i_op = &mqueue_dir_inode_operations;
176 inode->i_fop = &simple_dir_operations;
177 }
178 }
179 return inode;
180 out_inode:
181 make_bad_inode(inode);
182 iput(inode);
183 return NULL;
184 }
185
186 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
187 {
188 struct inode *inode;
189
190 sb->s_blocksize = PAGE_CACHE_SIZE;
191 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
192 sb->s_magic = MQUEUE_MAGIC;
193 sb->s_op = &mqueue_super_ops;
194
195 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
196 if (!inode)
197 return -ENOMEM;
198
199 sb->s_root = d_alloc_root(inode);
200 if (!sb->s_root) {
201 iput(inode);
202 return -ENOMEM;
203 }
204
205 return 0;
206 }
207
208 static int mqueue_get_sb(struct file_system_type *fs_type,
209 int flags, const char *dev_name,
210 void *data, struct vfsmount *mnt)
211 {
212 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
213 }
214
215 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
216 {
217 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
218
219 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
220 SLAB_CTOR_CONSTRUCTOR)
221 inode_init_once(&p->vfs_inode);
222 }
223
224 static struct inode *mqueue_alloc_inode(struct super_block *sb)
225 {
226 struct mqueue_inode_info *ei;
227
228 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
229 if (!ei)
230 return NULL;
231 return &ei->vfs_inode;
232 }
233
234 static void mqueue_destroy_inode(struct inode *inode)
235 {
236 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
237 }
238
239 static void mqueue_delete_inode(struct inode *inode)
240 {
241 struct mqueue_inode_info *info;
242 struct user_struct *user;
243 unsigned long mq_bytes;
244 int i;
245
246 if (S_ISDIR(inode->i_mode)) {
247 clear_inode(inode);
248 return;
249 }
250 info = MQUEUE_I(inode);
251 spin_lock(&info->lock);
252 for (i = 0; i < info->attr.mq_curmsgs; i++)
253 free_msg(info->messages[i]);
254 kfree(info->messages);
255 spin_unlock(&info->lock);
256
257 clear_inode(inode);
258
259 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
260 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
261 user = info->user;
262 if (user) {
263 spin_lock(&mq_lock);
264 user->mq_bytes -= mq_bytes;
265 queues_count--;
266 spin_unlock(&mq_lock);
267 free_uid(user);
268 }
269 }
270
271 static int mqueue_create(struct inode *dir, struct dentry *dentry,
272 int mode, struct nameidata *nd)
273 {
274 struct inode *inode;
275 struct mq_attr *attr = dentry->d_fsdata;
276 int error;
277
278 spin_lock(&mq_lock);
279 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
280 error = -ENOSPC;
281 goto out_lock;
282 }
283 queues_count++;
284 spin_unlock(&mq_lock);
285
286 inode = mqueue_get_inode(dir->i_sb, mode, attr);
287 if (!inode) {
288 error = -ENOMEM;
289 spin_lock(&mq_lock);
290 queues_count--;
291 goto out_lock;
292 }
293
294 dir->i_size += DIRENT_SIZE;
295 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
296
297 d_instantiate(dentry, inode);
298 dget(dentry);
299 return 0;
300 out_lock:
301 spin_unlock(&mq_lock);
302 return error;
303 }
304
305 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
306 {
307 struct inode *inode = dentry->d_inode;
308
309 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
310 dir->i_size -= DIRENT_SIZE;
311 inode->i_nlink--;
312 dput(dentry);
313 return 0;
314 }
315
316 /*
317 * This is routine for system read from queue file.
318 * To avoid mess with doing here some sort of mq_receive we allow
319 * to read only queue size & notification info (the only values
320 * that are interesting from user point of view and aren't accessible
321 * through std routines)
322 */
323 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
324 size_t count, loff_t * off)
325 {
326 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
327 char buffer[FILENT_SIZE];
328 size_t slen;
329 loff_t o;
330
331 if (!count)
332 return 0;
333
334 spin_lock(&info->lock);
335 snprintf(buffer, sizeof(buffer),
336 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
337 info->qsize,
338 info->notify_owner ? info->notify.sigev_notify : 0,
339 (info->notify_owner &&
340 info->notify.sigev_notify == SIGEV_SIGNAL) ?
341 info->notify.sigev_signo : 0,
342 info->notify_owner);
343 spin_unlock(&info->lock);
344 buffer[sizeof(buffer)-1] = '\0';
345 slen = strlen(buffer)+1;
346
347 o = *off;
348 if (o > slen)
349 return 0;
350
351 if (o + count > slen)
352 count = slen - o;
353
354 if (copy_to_user(u_data, buffer + o, count))
355 return -EFAULT;
356
357 *off = o + count;
358 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
359 return count;
360 }
361
362 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
363 {
364 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
365
366 spin_lock(&info->lock);
367 if (current->tgid == info->notify_owner)
368 remove_notification(info);
369
370 spin_unlock(&info->lock);
371 return 0;
372 }
373
374 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
375 {
376 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
377 int retval = 0;
378
379 poll_wait(filp, &info->wait_q, poll_tab);
380
381 spin_lock(&info->lock);
382 if (info->attr.mq_curmsgs)
383 retval = POLLIN | POLLRDNORM;
384
385 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
386 retval |= POLLOUT | POLLWRNORM;
387 spin_unlock(&info->lock);
388
389 return retval;
390 }
391
392 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
393 static void wq_add(struct mqueue_inode_info *info, int sr,
394 struct ext_wait_queue *ewp)
395 {
396 struct ext_wait_queue *walk;
397
398 ewp->task = current;
399
400 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
401 if (walk->task->static_prio <= current->static_prio) {
402 list_add_tail(&ewp->list, &walk->list);
403 return;
404 }
405 }
406 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
407 }
408
409 /*
410 * Puts current task to sleep. Caller must hold queue lock. After return
411 * lock isn't held.
412 * sr: SEND or RECV
413 */
414 static int wq_sleep(struct mqueue_inode_info *info, int sr,
415 long timeout, struct ext_wait_queue *ewp)
416 {
417 int retval;
418 signed long time;
419
420 wq_add(info, sr, ewp);
421
422 for (;;) {
423 set_current_state(TASK_INTERRUPTIBLE);
424
425 spin_unlock(&info->lock);
426 time = schedule_timeout(timeout);
427
428 while (ewp->state == STATE_PENDING)
429 cpu_relax();
430
431 if (ewp->state == STATE_READY) {
432 retval = 0;
433 goto out;
434 }
435 spin_lock(&info->lock);
436 if (ewp->state == STATE_READY) {
437 retval = 0;
438 goto out_unlock;
439 }
440 if (signal_pending(current)) {
441 retval = -ERESTARTSYS;
442 break;
443 }
444 if (time == 0) {
445 retval = -ETIMEDOUT;
446 break;
447 }
448 }
449 list_del(&ewp->list);
450 out_unlock:
451 spin_unlock(&info->lock);
452 out:
453 return retval;
454 }
455
456 /*
457 * Returns waiting task that should be serviced first or NULL if none exists
458 */
459 static struct ext_wait_queue *wq_get_first_waiter(
460 struct mqueue_inode_info *info, int sr)
461 {
462 struct list_head *ptr;
463
464 ptr = info->e_wait_q[sr].list.prev;
465 if (ptr == &info->e_wait_q[sr].list)
466 return NULL;
467 return list_entry(ptr, struct ext_wait_queue, list);
468 }
469
470 /* Auxiliary functions to manipulate messages' list */
471 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
472 {
473 int k;
474
475 k = info->attr.mq_curmsgs - 1;
476 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
477 info->messages[k + 1] = info->messages[k];
478 k--;
479 }
480 info->attr.mq_curmsgs++;
481 info->qsize += ptr->m_ts;
482 info->messages[k + 1] = ptr;
483 }
484
485 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
486 {
487 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
488 return info->messages[info->attr.mq_curmsgs];
489 }
490
491 static inline void set_cookie(struct sk_buff *skb, char code)
492 {
493 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
494 }
495
496 /*
497 * The next function is only to split too long sys_mq_timedsend
498 */
499 static void __do_notify(struct mqueue_inode_info *info)
500 {
501 /* notification
502 * invoked when there is registered process and there isn't process
503 * waiting synchronously for message AND state of queue changed from
504 * empty to not empty. Here we are sure that no one is waiting
505 * synchronously. */
506 if (info->notify_owner &&
507 info->attr.mq_curmsgs == 1) {
508 struct siginfo sig_i;
509 switch (info->notify.sigev_notify) {
510 case SIGEV_NONE:
511 break;
512 case SIGEV_SIGNAL:
513 /* sends signal */
514
515 sig_i.si_signo = info->notify.sigev_signo;
516 sig_i.si_errno = 0;
517 sig_i.si_code = SI_MESGQ;
518 sig_i.si_value = info->notify.sigev_value;
519 sig_i.si_pid = current->tgid;
520 sig_i.si_uid = current->uid;
521
522 kill_proc_info(info->notify.sigev_signo,
523 &sig_i, info->notify_owner);
524 break;
525 case SIGEV_THREAD:
526 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
527 netlink_sendskb(info->notify_sock,
528 info->notify_cookie, 0);
529 break;
530 }
531 /* after notification unregisters process */
532 info->notify_owner = 0;
533 }
534 wake_up(&info->wait_q);
535 }
536
537 static long prepare_timeout(const struct timespec __user *u_arg)
538 {
539 struct timespec ts, nowts;
540 long timeout;
541
542 if (u_arg) {
543 if (unlikely(copy_from_user(&ts, u_arg,
544 sizeof(struct timespec))))
545 return -EFAULT;
546
547 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
548 || ts.tv_nsec >= NSEC_PER_SEC))
549 return -EINVAL;
550 nowts = CURRENT_TIME;
551 /* first subtract as jiffies can't be too big */
552 ts.tv_sec -= nowts.tv_sec;
553 if (ts.tv_nsec < nowts.tv_nsec) {
554 ts.tv_nsec += NSEC_PER_SEC;
555 ts.tv_sec--;
556 }
557 ts.tv_nsec -= nowts.tv_nsec;
558 if (ts.tv_sec < 0)
559 return 0;
560
561 timeout = timespec_to_jiffies(&ts) + 1;
562 } else
563 return MAX_SCHEDULE_TIMEOUT;
564
565 return timeout;
566 }
567
568 static void remove_notification(struct mqueue_inode_info *info)
569 {
570 if (info->notify_owner != 0 &&
571 info->notify.sigev_notify == SIGEV_THREAD) {
572 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
573 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
574 }
575 info->notify_owner = 0;
576 }
577
578 static int mq_attr_ok(struct mq_attr *attr)
579 {
580 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
581 return 0;
582 if (capable(CAP_SYS_RESOURCE)) {
583 if (attr->mq_maxmsg > HARD_MSGMAX)
584 return 0;
585 } else {
586 if (attr->mq_maxmsg > msg_max ||
587 attr->mq_msgsize > msgsize_max)
588 return 0;
589 }
590 /* check for overflow */
591 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
592 return 0;
593 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
594 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
595 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
596 return 0;
597 return 1;
598 }
599
600 /*
601 * Invoked when creating a new queue via sys_mq_open
602 */
603 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
604 int oflag, mode_t mode, struct mq_attr __user *u_attr)
605 {
606 struct mq_attr attr;
607 int ret;
608
609 if (u_attr) {
610 ret = -EFAULT;
611 if (copy_from_user(&attr, u_attr, sizeof(attr)))
612 goto out;
613 ret = -EINVAL;
614 if (!mq_attr_ok(&attr))
615 goto out;
616 /* store for use during create */
617 dentry->d_fsdata = &attr;
618 }
619
620 mode &= ~current->fs->umask;
621 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
622 dentry->d_fsdata = NULL;
623 if (ret)
624 goto out;
625
626 return dentry_open(dentry, mqueue_mnt, oflag);
627
628 out:
629 dput(dentry);
630 mntput(mqueue_mnt);
631 return ERR_PTR(ret);
632 }
633
634 /* Opens existing queue */
635 static struct file *do_open(struct dentry *dentry, int oflag)
636 {
637 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
638 MAY_READ | MAY_WRITE };
639
640 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
641 dput(dentry);
642 mntput(mqueue_mnt);
643 return ERR_PTR(-EINVAL);
644 }
645
646 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
647 dput(dentry);
648 mntput(mqueue_mnt);
649 return ERR_PTR(-EACCES);
650 }
651
652 return dentry_open(dentry, mqueue_mnt, oflag);
653 }
654
655 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
656 struct mq_attr __user *u_attr)
657 {
658 struct dentry *dentry;
659 struct file *filp;
660 char *name;
661 int fd, error;
662
663 error = audit_mq_open(oflag, mode, u_attr);
664 if (error != 0)
665 return error;
666
667 if (IS_ERR(name = getname(u_name)))
668 return PTR_ERR(name);
669
670 fd = get_unused_fd();
671 if (fd < 0)
672 goto out_putname;
673
674 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
675 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
676 if (IS_ERR(dentry)) {
677 error = PTR_ERR(dentry);
678 goto out_err;
679 }
680 mntget(mqueue_mnt);
681
682 if (oflag & O_CREAT) {
683 if (dentry->d_inode) { /* entry already exists */
684 error = -EEXIST;
685 if (oflag & O_EXCL)
686 goto out;
687 filp = do_open(dentry, oflag);
688 } else {
689 filp = do_create(mqueue_mnt->mnt_root, dentry,
690 oflag, mode, u_attr);
691 }
692 } else {
693 error = -ENOENT;
694 if (!dentry->d_inode)
695 goto out;
696 filp = do_open(dentry, oflag);
697 }
698
699 if (IS_ERR(filp)) {
700 error = PTR_ERR(filp);
701 goto out_putfd;
702 }
703
704 set_close_on_exec(fd, 1);
705 fd_install(fd, filp);
706 goto out_upsem;
707
708 out:
709 dput(dentry);
710 mntput(mqueue_mnt);
711 out_putfd:
712 put_unused_fd(fd);
713 out_err:
714 fd = error;
715 out_upsem:
716 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
717 out_putname:
718 putname(name);
719 return fd;
720 }
721
722 asmlinkage long sys_mq_unlink(const char __user *u_name)
723 {
724 int err;
725 char *name;
726 struct dentry *dentry;
727 struct inode *inode = NULL;
728
729 name = getname(u_name);
730 if (IS_ERR(name))
731 return PTR_ERR(name);
732
733 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
734 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
735 if (IS_ERR(dentry)) {
736 err = PTR_ERR(dentry);
737 goto out_unlock;
738 }
739
740 if (!dentry->d_inode) {
741 err = -ENOENT;
742 goto out_err;
743 }
744
745 inode = dentry->d_inode;
746 if (inode)
747 atomic_inc(&inode->i_count);
748
749 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
750 out_err:
751 dput(dentry);
752
753 out_unlock:
754 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
755 putname(name);
756 if (inode)
757 iput(inode);
758
759 return err;
760 }
761
762 /* Pipelined send and receive functions.
763 *
764 * If a receiver finds no waiting message, then it registers itself in the
765 * list of waiting receivers. A sender checks that list before adding the new
766 * message into the message array. If there is a waiting receiver, then it
767 * bypasses the message array and directly hands the message over to the
768 * receiver.
769 * The receiver accepts the message and returns without grabbing the queue
770 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
771 * are necessary. The same algorithm is used for sysv semaphores, see
772 * ipc/sem.c for more details.
773 *
774 * The same algorithm is used for senders.
775 */
776
777 /* pipelined_send() - send a message directly to the task waiting in
778 * sys_mq_timedreceive() (without inserting message into a queue).
779 */
780 static inline void pipelined_send(struct mqueue_inode_info *info,
781 struct msg_msg *message,
782 struct ext_wait_queue *receiver)
783 {
784 receiver->msg = message;
785 list_del(&receiver->list);
786 receiver->state = STATE_PENDING;
787 wake_up_process(receiver->task);
788 smp_wmb();
789 receiver->state = STATE_READY;
790 }
791
792 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
793 * gets its message and put to the queue (we have one free place for sure). */
794 static inline void pipelined_receive(struct mqueue_inode_info *info)
795 {
796 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
797
798 if (!sender) {
799 /* for poll */
800 wake_up_interruptible(&info->wait_q);
801 return;
802 }
803 msg_insert(sender->msg, info);
804 list_del(&sender->list);
805 sender->state = STATE_PENDING;
806 wake_up_process(sender->task);
807 smp_wmb();
808 sender->state = STATE_READY;
809 }
810
811 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
812 size_t msg_len, unsigned int msg_prio,
813 const struct timespec __user *u_abs_timeout)
814 {
815 struct file *filp;
816 struct inode *inode;
817 struct ext_wait_queue wait;
818 struct ext_wait_queue *receiver;
819 struct msg_msg *msg_ptr;
820 struct mqueue_inode_info *info;
821 long timeout;
822 int ret;
823
824 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
825 if (ret != 0)
826 return ret;
827
828 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
829 return -EINVAL;
830
831 timeout = prepare_timeout(u_abs_timeout);
832
833 ret = -EBADF;
834 filp = fget(mqdes);
835 if (unlikely(!filp))
836 goto out;
837
838 inode = filp->f_dentry->d_inode;
839 if (unlikely(filp->f_op != &mqueue_file_operations))
840 goto out_fput;
841 info = MQUEUE_I(inode);
842
843 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
844 goto out_fput;
845
846 if (unlikely(msg_len > info->attr.mq_msgsize)) {
847 ret = -EMSGSIZE;
848 goto out_fput;
849 }
850
851 /* First try to allocate memory, before doing anything with
852 * existing queues. */
853 msg_ptr = load_msg(u_msg_ptr, msg_len);
854 if (IS_ERR(msg_ptr)) {
855 ret = PTR_ERR(msg_ptr);
856 goto out_fput;
857 }
858 msg_ptr->m_ts = msg_len;
859 msg_ptr->m_type = msg_prio;
860
861 spin_lock(&info->lock);
862
863 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
864 if (filp->f_flags & O_NONBLOCK) {
865 spin_unlock(&info->lock);
866 ret = -EAGAIN;
867 } else if (unlikely(timeout < 0)) {
868 spin_unlock(&info->lock);
869 ret = timeout;
870 } else {
871 wait.task = current;
872 wait.msg = (void *) msg_ptr;
873 wait.state = STATE_NONE;
874 ret = wq_sleep(info, SEND, timeout, &wait);
875 }
876 if (ret < 0)
877 free_msg(msg_ptr);
878 } else {
879 receiver = wq_get_first_waiter(info, RECV);
880 if (receiver) {
881 pipelined_send(info, msg_ptr, receiver);
882 } else {
883 /* adds message to the queue */
884 msg_insert(msg_ptr, info);
885 __do_notify(info);
886 }
887 inode->i_atime = inode->i_mtime = inode->i_ctime =
888 CURRENT_TIME;
889 spin_unlock(&info->lock);
890 ret = 0;
891 }
892 out_fput:
893 fput(filp);
894 out:
895 return ret;
896 }
897
898 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
899 size_t msg_len, unsigned int __user *u_msg_prio,
900 const struct timespec __user *u_abs_timeout)
901 {
902 long timeout;
903 ssize_t ret;
904 struct msg_msg *msg_ptr;
905 struct file *filp;
906 struct inode *inode;
907 struct mqueue_inode_info *info;
908 struct ext_wait_queue wait;
909
910 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
911 if (ret != 0)
912 return ret;
913
914 timeout = prepare_timeout(u_abs_timeout);
915
916 ret = -EBADF;
917 filp = fget(mqdes);
918 if (unlikely(!filp))
919 goto out;
920
921 inode = filp->f_dentry->d_inode;
922 if (unlikely(filp->f_op != &mqueue_file_operations))
923 goto out_fput;
924 info = MQUEUE_I(inode);
925
926 if (unlikely(!(filp->f_mode & FMODE_READ)))
927 goto out_fput;
928
929 /* checks if buffer is big enough */
930 if (unlikely(msg_len < info->attr.mq_msgsize)) {
931 ret = -EMSGSIZE;
932 goto out_fput;
933 }
934
935 spin_lock(&info->lock);
936 if (info->attr.mq_curmsgs == 0) {
937 if (filp->f_flags & O_NONBLOCK) {
938 spin_unlock(&info->lock);
939 ret = -EAGAIN;
940 msg_ptr = NULL;
941 } else if (unlikely(timeout < 0)) {
942 spin_unlock(&info->lock);
943 ret = timeout;
944 msg_ptr = NULL;
945 } else {
946 wait.task = current;
947 wait.state = STATE_NONE;
948 ret = wq_sleep(info, RECV, timeout, &wait);
949 msg_ptr = wait.msg;
950 }
951 } else {
952 msg_ptr = msg_get(info);
953
954 inode->i_atime = inode->i_mtime = inode->i_ctime =
955 CURRENT_TIME;
956
957 /* There is now free space in queue. */
958 pipelined_receive(info);
959 spin_unlock(&info->lock);
960 ret = 0;
961 }
962 if (ret == 0) {
963 ret = msg_ptr->m_ts;
964
965 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
966 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
967 ret = -EFAULT;
968 }
969 free_msg(msg_ptr);
970 }
971 out_fput:
972 fput(filp);
973 out:
974 return ret;
975 }
976
977 /*
978 * Notes: the case when user wants us to deregister (with NULL as pointer)
979 * and he isn't currently owner of notification, will be silently discarded.
980 * It isn't explicitly defined in the POSIX.
981 */
982 asmlinkage long sys_mq_notify(mqd_t mqdes,
983 const struct sigevent __user *u_notification)
984 {
985 int ret;
986 struct file *filp;
987 struct sock *sock;
988 struct inode *inode;
989 struct sigevent notification;
990 struct mqueue_inode_info *info;
991 struct sk_buff *nc;
992
993 ret = audit_mq_notify(mqdes, u_notification);
994 if (ret != 0)
995 return ret;
996
997 nc = NULL;
998 sock = NULL;
999 if (u_notification != NULL) {
1000 if (copy_from_user(&notification, u_notification,
1001 sizeof(struct sigevent)))
1002 return -EFAULT;
1003
1004 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1005 notification.sigev_notify != SIGEV_SIGNAL &&
1006 notification.sigev_notify != SIGEV_THREAD))
1007 return -EINVAL;
1008 if (notification.sigev_notify == SIGEV_SIGNAL &&
1009 !valid_signal(notification.sigev_signo)) {
1010 return -EINVAL;
1011 }
1012 if (notification.sigev_notify == SIGEV_THREAD) {
1013 /* create the notify skb */
1014 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1015 ret = -ENOMEM;
1016 if (!nc)
1017 goto out;
1018 ret = -EFAULT;
1019 if (copy_from_user(nc->data,
1020 notification.sigev_value.sival_ptr,
1021 NOTIFY_COOKIE_LEN)) {
1022 goto out;
1023 }
1024
1025 /* TODO: add a header? */
1026 skb_put(nc, NOTIFY_COOKIE_LEN);
1027 /* and attach it to the socket */
1028 retry:
1029 filp = fget(notification.sigev_signo);
1030 ret = -EBADF;
1031 if (!filp)
1032 goto out;
1033 sock = netlink_getsockbyfilp(filp);
1034 fput(filp);
1035 if (IS_ERR(sock)) {
1036 ret = PTR_ERR(sock);
1037 sock = NULL;
1038 goto out;
1039 }
1040
1041 ret = netlink_attachskb(sock, nc, 0,
1042 MAX_SCHEDULE_TIMEOUT, NULL);
1043 if (ret == 1)
1044 goto retry;
1045 if (ret) {
1046 sock = NULL;
1047 nc = NULL;
1048 goto out;
1049 }
1050 }
1051 }
1052
1053 ret = -EBADF;
1054 filp = fget(mqdes);
1055 if (!filp)
1056 goto out;
1057
1058 inode = filp->f_dentry->d_inode;
1059 if (unlikely(filp->f_op != &mqueue_file_operations))
1060 goto out_fput;
1061 info = MQUEUE_I(inode);
1062
1063 ret = 0;
1064 spin_lock(&info->lock);
1065 if (u_notification == NULL) {
1066 if (info->notify_owner == current->tgid) {
1067 remove_notification(info);
1068 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1069 }
1070 } else if (info->notify_owner != 0) {
1071 ret = -EBUSY;
1072 } else {
1073 switch (notification.sigev_notify) {
1074 case SIGEV_NONE:
1075 info->notify.sigev_notify = SIGEV_NONE;
1076 break;
1077 case SIGEV_THREAD:
1078 info->notify_sock = sock;
1079 info->notify_cookie = nc;
1080 sock = NULL;
1081 nc = NULL;
1082 info->notify.sigev_notify = SIGEV_THREAD;
1083 break;
1084 case SIGEV_SIGNAL:
1085 info->notify.sigev_signo = notification.sigev_signo;
1086 info->notify.sigev_value = notification.sigev_value;
1087 info->notify.sigev_notify = SIGEV_SIGNAL;
1088 break;
1089 }
1090 info->notify_owner = current->tgid;
1091 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1092 }
1093 spin_unlock(&info->lock);
1094 out_fput:
1095 fput(filp);
1096 out:
1097 if (sock) {
1098 netlink_detachskb(sock, nc);
1099 } else if (nc) {
1100 dev_kfree_skb(nc);
1101 }
1102 return ret;
1103 }
1104
1105 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1106 const struct mq_attr __user *u_mqstat,
1107 struct mq_attr __user *u_omqstat)
1108 {
1109 int ret;
1110 struct mq_attr mqstat, omqstat;
1111 struct file *filp;
1112 struct inode *inode;
1113 struct mqueue_inode_info *info;
1114
1115 if (u_mqstat != NULL) {
1116 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1117 return -EFAULT;
1118 if (mqstat.mq_flags & (~O_NONBLOCK))
1119 return -EINVAL;
1120 }
1121
1122 ret = -EBADF;
1123 filp = fget(mqdes);
1124 if (!filp)
1125 goto out;
1126
1127 inode = filp->f_dentry->d_inode;
1128 if (unlikely(filp->f_op != &mqueue_file_operations))
1129 goto out_fput;
1130 info = MQUEUE_I(inode);
1131
1132 spin_lock(&info->lock);
1133
1134 omqstat = info->attr;
1135 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1136 if (u_mqstat) {
1137 ret = audit_mq_getsetattr(mqdes, &mqstat);
1138 if (ret != 0)
1139 goto out;
1140 if (mqstat.mq_flags & O_NONBLOCK)
1141 filp->f_flags |= O_NONBLOCK;
1142 else
1143 filp->f_flags &= ~O_NONBLOCK;
1144
1145 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1146 }
1147
1148 spin_unlock(&info->lock);
1149
1150 ret = 0;
1151 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1152 sizeof(struct mq_attr)))
1153 ret = -EFAULT;
1154
1155 out_fput:
1156 fput(filp);
1157 out:
1158 return ret;
1159 }
1160
1161 static struct inode_operations mqueue_dir_inode_operations = {
1162 .lookup = simple_lookup,
1163 .create = mqueue_create,
1164 .unlink = mqueue_unlink,
1165 };
1166
1167 static struct file_operations mqueue_file_operations = {
1168 .flush = mqueue_flush_file,
1169 .poll = mqueue_poll_file,
1170 .read = mqueue_read_file,
1171 };
1172
1173 static struct super_operations mqueue_super_ops = {
1174 .alloc_inode = mqueue_alloc_inode,
1175 .destroy_inode = mqueue_destroy_inode,
1176 .statfs = simple_statfs,
1177 .delete_inode = mqueue_delete_inode,
1178 .drop_inode = generic_delete_inode,
1179 };
1180
1181 static struct file_system_type mqueue_fs_type = {
1182 .name = "mqueue",
1183 .get_sb = mqueue_get_sb,
1184 .kill_sb = kill_litter_super,
1185 };
1186
1187 static int msg_max_limit_min = DFLT_MSGMAX;
1188 static int msg_max_limit_max = HARD_MSGMAX;
1189
1190 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1191 static int msg_maxsize_limit_max = INT_MAX;
1192
1193 static ctl_table mq_sysctls[] = {
1194 {
1195 .ctl_name = CTL_QUEUESMAX,
1196 .procname = "queues_max",
1197 .data = &queues_max,
1198 .maxlen = sizeof(int),
1199 .mode = 0644,
1200 .proc_handler = &proc_dointvec,
1201 },
1202 {
1203 .ctl_name = CTL_MSGMAX,
1204 .procname = "msg_max",
1205 .data = &msg_max,
1206 .maxlen = sizeof(int),
1207 .mode = 0644,
1208 .proc_handler = &proc_dointvec_minmax,
1209 .extra1 = &msg_max_limit_min,
1210 .extra2 = &msg_max_limit_max,
1211 },
1212 {
1213 .ctl_name = CTL_MSGSIZEMAX,
1214 .procname = "msgsize_max",
1215 .data = &msgsize_max,
1216 .maxlen = sizeof(int),
1217 .mode = 0644,
1218 .proc_handler = &proc_dointvec_minmax,
1219 .extra1 = &msg_maxsize_limit_min,
1220 .extra2 = &msg_maxsize_limit_max,
1221 },
1222 { .ctl_name = 0 }
1223 };
1224
1225 static ctl_table mq_sysctl_dir[] = {
1226 {
1227 .ctl_name = FS_MQUEUE,
1228 .procname = "mqueue",
1229 .mode = 0555,
1230 .child = mq_sysctls,
1231 },
1232 { .ctl_name = 0 }
1233 };
1234
1235 static ctl_table mq_sysctl_root[] = {
1236 {
1237 .ctl_name = CTL_FS,
1238 .procname = "fs",
1239 .mode = 0555,
1240 .child = mq_sysctl_dir,
1241 },
1242 { .ctl_name = 0 }
1243 };
1244
1245 static int __init init_mqueue_fs(void)
1246 {
1247 int error;
1248
1249 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1250 sizeof(struct mqueue_inode_info), 0,
1251 SLAB_HWCACHE_ALIGN, init_once, NULL);
1252 if (mqueue_inode_cachep == NULL)
1253 return -ENOMEM;
1254
1255 /* ignore failues - they are not fatal */
1256 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1257
1258 error = register_filesystem(&mqueue_fs_type);
1259 if (error)
1260 goto out_sysctl;
1261
1262 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1263 error = PTR_ERR(mqueue_mnt);
1264 goto out_filesystem;
1265 }
1266
1267 /* internal initialization - not common for vfs */
1268 queues_count = 0;
1269 spin_lock_init(&mq_lock);
1270
1271 return 0;
1272
1273 out_filesystem:
1274 unregister_filesystem(&mqueue_fs_type);
1275 out_sysctl:
1276 if (mq_sysctl_table)
1277 unregister_sysctl_table(mq_sysctl_table);
1278 if (kmem_cache_destroy(mqueue_inode_cachep)) {
1279 printk(KERN_INFO
1280 "mqueue_inode_cache: not all structures were freed\n");
1281 }
1282 return error;
1283 }
1284
1285 __initcall(init_mqueue_fs);
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