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[AX25]: Use kmemdup
[linux-2.6/linux-mips.git] / ipc / mqueue.c
blob7c274002c9f5911d21a5f6a704e85be40d1e1777
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@gmail.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 struct pid* 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_blocks = 0;
119 inode->i_mtime = inode->i_ctime = inode->i_atime =
120 CURRENT_TIME;
121
122 if (S_ISREG(mode)) {
123 struct mqueue_inode_info *info;
124 struct task_struct *p = current;
125 struct user_struct *u = p->user;
126 unsigned long mq_bytes, mq_msg_tblsz;
127
128 inode->i_fop = &mqueue_file_operations;
129 inode->i_size = FILENT_SIZE;
130 /* mqueue specific info */
131 info = MQUEUE_I(inode);
132 spin_lock_init(&info->lock);
133 init_waitqueue_head(&info->wait_q);
134 INIT_LIST_HEAD(&info->e_wait_q[0].list);
135 INIT_LIST_HEAD(&info->e_wait_q[1].list);
136 info->messages = NULL;
137 info->notify_owner = NULL;
138 info->qsize = 0;
139 info->user = NULL; /* set when all is ok */
140 memset(&info->attr, 0, sizeof(info->attr));
141 info->attr.mq_maxmsg = DFLT_MSGMAX;
142 info->attr.mq_msgsize = DFLT_MSGSIZEMAX;
143 if (attr) {
144 info->attr.mq_maxmsg = attr->mq_maxmsg;
145 info->attr.mq_msgsize = attr->mq_msgsize;
146 }
147 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
148 mq_bytes = (mq_msg_tblsz +
149 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
150
151 spin_lock(&mq_lock);
152 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
153 u->mq_bytes + mq_bytes >
154 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
155 spin_unlock(&mq_lock);
156 goto out_inode;
157 }
158 u->mq_bytes += mq_bytes;
159 spin_unlock(&mq_lock);
160
161 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
162 if (!info->messages) {
163 spin_lock(&mq_lock);
164 u->mq_bytes -= mq_bytes;
165 spin_unlock(&mq_lock);
166 goto out_inode;
167 }
168 /* all is ok */
169 info->user = get_uid(u);
170 } else if (S_ISDIR(mode)) {
171 inc_nlink(inode);
172 /* Some things misbehave if size == 0 on a directory */
173 inode->i_size = 2 * DIRENT_SIZE;
174 inode->i_op = &mqueue_dir_inode_operations;
175 inode->i_fop = &simple_dir_operations;
176 }
177 }
178 return inode;
179 out_inode:
180 make_bad_inode(inode);
181 iput(inode);
182 return NULL;
183 }
184
185 static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
186 {
187 struct inode *inode;
188
189 sb->s_blocksize = PAGE_CACHE_SIZE;
190 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
191 sb->s_magic = MQUEUE_MAGIC;
192 sb->s_op = &mqueue_super_ops;
193
194 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
195 if (!inode)
196 return -ENOMEM;
197
198 sb->s_root = d_alloc_root(inode);
199 if (!sb->s_root) {
200 iput(inode);
201 return -ENOMEM;
202 }
203
204 return 0;
205 }
206
207 static int mqueue_get_sb(struct file_system_type *fs_type,
208 int flags, const char *dev_name,
209 void *data, struct vfsmount *mnt)
210 {
211 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
212 }
213
214 static void init_once(void *foo, kmem_cache_t * cachep, unsigned long flags)
215 {
216 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
217
218 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
219 SLAB_CTOR_CONSTRUCTOR)
220 inode_init_once(&p->vfs_inode);
221 }
222
223 static struct inode *mqueue_alloc_inode(struct super_block *sb)
224 {
225 struct mqueue_inode_info *ei;
226
227 ei = kmem_cache_alloc(mqueue_inode_cachep, SLAB_KERNEL);
228 if (!ei)
229 return NULL;
230 return &ei->vfs_inode;
231 }
232
233 static void mqueue_destroy_inode(struct inode *inode)
234 {
235 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
236 }
237
238 static void mqueue_delete_inode(struct inode *inode)
239 {
240 struct mqueue_inode_info *info;
241 struct user_struct *user;
242 unsigned long mq_bytes;
243 int i;
244
245 if (S_ISDIR(inode->i_mode)) {
246 clear_inode(inode);
247 return;
248 }
249 info = MQUEUE_I(inode);
250 spin_lock(&info->lock);
251 for (i = 0; i < info->attr.mq_curmsgs; i++)
252 free_msg(info->messages[i]);
253 kfree(info->messages);
254 spin_unlock(&info->lock);
255
256 clear_inode(inode);
257
258 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
259 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
260 user = info->user;
261 if (user) {
262 spin_lock(&mq_lock);
263 user->mq_bytes -= mq_bytes;
264 queues_count--;
265 spin_unlock(&mq_lock);
266 free_uid(user);
267 }
268 }
269
270 static int mqueue_create(struct inode *dir, struct dentry *dentry,
271 int mode, struct nameidata *nd)
272 {
273 struct inode *inode;
274 struct mq_attr *attr = dentry->d_fsdata;
275 int error;
276
277 spin_lock(&mq_lock);
278 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
279 error = -ENOSPC;
280 goto out_lock;
281 }
282 queues_count++;
283 spin_unlock(&mq_lock);
284
285 inode = mqueue_get_inode(dir->i_sb, mode, attr);
286 if (!inode) {
287 error = -ENOMEM;
288 spin_lock(&mq_lock);
289 queues_count--;
290 goto out_lock;
291 }
292
293 dir->i_size += DIRENT_SIZE;
294 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
295
296 d_instantiate(dentry, inode);
297 dget(dentry);
298 return 0;
299 out_lock:
300 spin_unlock(&mq_lock);
301 return error;
302 }
303
304 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
305 {
306 struct inode *inode = dentry->d_inode;
307
308 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
309 dir->i_size -= DIRENT_SIZE;
310 drop_nlink(inode);
311 dput(dentry);
312 return 0;
313 }
314
315 /*
316 * This is routine for system read from queue file.
317 * To avoid mess with doing here some sort of mq_receive we allow
318 * to read only queue size & notification info (the only values
319 * that are interesting from user point of view and aren't accessible
320 * through std routines)
321 */
322 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
323 size_t count, loff_t * off)
324 {
325 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
326 char buffer[FILENT_SIZE];
327 size_t slen;
328 loff_t o;
329
330 if (!count)
331 return 0;
332
333 spin_lock(&info->lock);
334 snprintf(buffer, sizeof(buffer),
335 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
336 info->qsize,
337 info->notify_owner ? info->notify.sigev_notify : 0,
338 (info->notify_owner &&
339 info->notify.sigev_notify == SIGEV_SIGNAL) ?
340 info->notify.sigev_signo : 0,
341 pid_nr(info->notify_owner));
342 spin_unlock(&info->lock);
343 buffer[sizeof(buffer)-1] = '\0';
344 slen = strlen(buffer)+1;
345
346 o = *off;
347 if (o > slen)
348 return 0;
349
350 if (o + count > slen)
351 count = slen - o;
352
353 if (copy_to_user(u_data, buffer + o, count))
354 return -EFAULT;
355
356 *off = o + count;
357 filp->f_dentry->d_inode->i_atime = filp->f_dentry->d_inode->i_ctime = CURRENT_TIME;
358 return count;
359 }
360
361 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
362 {
363 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
364
365 spin_lock(&info->lock);
366 if (task_tgid(current) == info->notify_owner)
367 remove_notification(info);
368
369 spin_unlock(&info->lock);
370 return 0;
371 }
372
373 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
374 {
375 struct mqueue_inode_info *info = MQUEUE_I(filp->f_dentry->d_inode);
376 int retval = 0;
377
378 poll_wait(filp, &info->wait_q, poll_tab);
379
380 spin_lock(&info->lock);
381 if (info->attr.mq_curmsgs)
382 retval = POLLIN | POLLRDNORM;
383
384 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
385 retval |= POLLOUT | POLLWRNORM;
386 spin_unlock(&info->lock);
387
388 return retval;
389 }
390
391 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
392 static void wq_add(struct mqueue_inode_info *info, int sr,
393 struct ext_wait_queue *ewp)
394 {
395 struct ext_wait_queue *walk;
396
397 ewp->task = current;
398
399 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
400 if (walk->task->static_prio <= current->static_prio) {
401 list_add_tail(&ewp->list, &walk->list);
402 return;
403 }
404 }
405 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
406 }
407
408 /*
409 * Puts current task to sleep. Caller must hold queue lock. After return
410 * lock isn't held.
411 * sr: SEND or RECV
412 */
413 static int wq_sleep(struct mqueue_inode_info *info, int sr,
414 long timeout, struct ext_wait_queue *ewp)
415 {
416 int retval;
417 signed long time;
418
419 wq_add(info, sr, ewp);
420
421 for (;;) {
422 set_current_state(TASK_INTERRUPTIBLE);
423
424 spin_unlock(&info->lock);
425 time = schedule_timeout(timeout);
426
427 while (ewp->state == STATE_PENDING)
428 cpu_relax();
429
430 if (ewp->state == STATE_READY) {
431 retval = 0;
432 goto out;
433 }
434 spin_lock(&info->lock);
435 if (ewp->state == STATE_READY) {
436 retval = 0;
437 goto out_unlock;
438 }
439 if (signal_pending(current)) {
440 retval = -ERESTARTSYS;
441 break;
442 }
443 if (time == 0) {
444 retval = -ETIMEDOUT;
445 break;
446 }
447 }
448 list_del(&ewp->list);
449 out_unlock:
450 spin_unlock(&info->lock);
451 out:
452 return retval;
453 }
454
455 /*
456 * Returns waiting task that should be serviced first or NULL if none exists
457 */
458 static struct ext_wait_queue *wq_get_first_waiter(
459 struct mqueue_inode_info *info, int sr)
460 {
461 struct list_head *ptr;
462
463 ptr = info->e_wait_q[sr].list.prev;
464 if (ptr == &info->e_wait_q[sr].list)
465 return NULL;
466 return list_entry(ptr, struct ext_wait_queue, list);
467 }
468
469 /* Auxiliary functions to manipulate messages' list */
470 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
471 {
472 int k;
473
474 k = info->attr.mq_curmsgs - 1;
475 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
476 info->messages[k + 1] = info->messages[k];
477 k--;
478 }
479 info->attr.mq_curmsgs++;
480 info->qsize += ptr->m_ts;
481 info->messages[k + 1] = ptr;
482 }
483
484 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
485 {
486 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
487 return info->messages[info->attr.mq_curmsgs];
488 }
489
490 static inline void set_cookie(struct sk_buff *skb, char code)
491 {
492 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
493 }
494
495 /*
496 * The next function is only to split too long sys_mq_timedsend
497 */
498 static void __do_notify(struct mqueue_inode_info *info)
499 {
500 /* notification
501 * invoked when there is registered process and there isn't process
502 * waiting synchronously for message AND state of queue changed from
503 * empty to not empty. Here we are sure that no one is waiting
504 * synchronously. */
505 if (info->notify_owner &&
506 info->attr.mq_curmsgs == 1) {
507 struct siginfo sig_i;
508 switch (info->notify.sigev_notify) {
509 case SIGEV_NONE:
510 break;
511 case SIGEV_SIGNAL:
512 /* sends signal */
513
514 sig_i.si_signo = info->notify.sigev_signo;
515 sig_i.si_errno = 0;
516 sig_i.si_code = SI_MESGQ;
517 sig_i.si_value = info->notify.sigev_value;
518 sig_i.si_pid = current->tgid;
519 sig_i.si_uid = current->uid;
520
521 kill_pid_info(info->notify.sigev_signo,
522 &sig_i, info->notify_owner);
523 break;
524 case SIGEV_THREAD:
525 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
526 netlink_sendskb(info->notify_sock,
527 info->notify_cookie, 0);
528 break;
529 }
530 /* after notification unregisters process */
531 put_pid(info->notify_owner);
532 info->notify_owner = NULL;
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 != NULL &&
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 put_pid(info->notify_owner);
576 info->notify_owner = NULL;
577 }
578
579 static int mq_attr_ok(struct mq_attr *attr)
580 {
581 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
582 return 0;
583 if (capable(CAP_SYS_RESOURCE)) {
584 if (attr->mq_maxmsg > HARD_MSGMAX)
585 return 0;
586 } else {
587 if (attr->mq_maxmsg > msg_max ||
588 attr->mq_msgsize > msgsize_max)
589 return 0;
590 }
591 /* check for overflow */
592 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
593 return 0;
594 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
595 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
596 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
597 return 0;
598 return 1;
599 }
600
601 /*
602 * Invoked when creating a new queue via sys_mq_open
603 */
604 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
605 int oflag, mode_t mode, struct mq_attr __user *u_attr)
606 {
607 struct mq_attr attr;
608 int ret;
609
610 if (u_attr) {
611 ret = -EFAULT;
612 if (copy_from_user(&attr, u_attr, sizeof(attr)))
613 goto out;
614 ret = -EINVAL;
615 if (!mq_attr_ok(&attr))
616 goto out;
617 /* store for use during create */
618 dentry->d_fsdata = &attr;
619 }
620
621 mode &= ~current->fs->umask;
622 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
623 dentry->d_fsdata = NULL;
624 if (ret)
625 goto out;
626
627 return dentry_open(dentry, mqueue_mnt, oflag);
628
629 out:
630 dput(dentry);
631 mntput(mqueue_mnt);
632 return ERR_PTR(ret);
633 }
634
635 /* Opens existing queue */
636 static struct file *do_open(struct dentry *dentry, int oflag)
637 {
638 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
639 MAY_READ | MAY_WRITE };
640
641 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
642 dput(dentry);
643 mntput(mqueue_mnt);
644 return ERR_PTR(-EINVAL);
645 }
646
647 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
648 dput(dentry);
649 mntput(mqueue_mnt);
650 return ERR_PTR(-EACCES);
651 }
652
653 return dentry_open(dentry, mqueue_mnt, oflag);
654 }
655
656 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
657 struct mq_attr __user *u_attr)
658 {
659 struct dentry *dentry;
660 struct file *filp;
661 char *name;
662 int fd, error;
663
664 error = audit_mq_open(oflag, mode, u_attr);
665 if (error != 0)
666 return error;
667
668 if (IS_ERR(name = getname(u_name)))
669 return PTR_ERR(name);
670
671 fd = get_unused_fd();
672 if (fd < 0)
673 goto out_putname;
674
675 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
676 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
677 if (IS_ERR(dentry)) {
678 error = PTR_ERR(dentry);
679 goto out_err;
680 }
681 mntget(mqueue_mnt);
682
683 if (oflag & O_CREAT) {
684 if (dentry->d_inode) { /* entry already exists */
685 error = -EEXIST;
686 if (oflag & O_EXCL)
687 goto out;
688 filp = do_open(dentry, oflag);
689 } else {
690 filp = do_create(mqueue_mnt->mnt_root, dentry,
691 oflag, mode, u_attr);
692 }
693 } else {
694 error = -ENOENT;
695 if (!dentry->d_inode)
696 goto out;
697 filp = do_open(dentry, oflag);
698 }
699
700 if (IS_ERR(filp)) {
701 error = PTR_ERR(filp);
702 goto out_putfd;
703 }
704
705 set_close_on_exec(fd, 1);
706 fd_install(fd, filp);
707 goto out_upsem;
708
709 out:
710 dput(dentry);
711 mntput(mqueue_mnt);
712 out_putfd:
713 put_unused_fd(fd);
714 out_err:
715 fd = error;
716 out_upsem:
717 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
718 out_putname:
719 putname(name);
720 return fd;
721 }
722
723 asmlinkage long sys_mq_unlink(const char __user *u_name)
724 {
725 int err;
726 char *name;
727 struct dentry *dentry;
728 struct inode *inode = NULL;
729
730 name = getname(u_name);
731 if (IS_ERR(name))
732 return PTR_ERR(name);
733
734 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
735 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
736 if (IS_ERR(dentry)) {
737 err = PTR_ERR(dentry);
738 goto out_unlock;
739 }
740
741 if (!dentry->d_inode) {
742 err = -ENOENT;
743 goto out_err;
744 }
745
746 inode = dentry->d_inode;
747 if (inode)
748 atomic_inc(&inode->i_count);
749
750 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
751 out_err:
752 dput(dentry);
753
754 out_unlock:
755 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
756 putname(name);
757 if (inode)
758 iput(inode);
759
760 return err;
761 }
762
763 /* Pipelined send and receive functions.
764 *
765 * If a receiver finds no waiting message, then it registers itself in the
766 * list of waiting receivers. A sender checks that list before adding the new
767 * message into the message array. If there is a waiting receiver, then it
768 * bypasses the message array and directly hands the message over to the
769 * receiver.
770 * The receiver accepts the message and returns without grabbing the queue
771 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
772 * are necessary. The same algorithm is used for sysv semaphores, see
773 * ipc/sem.c for more details.
774 *
775 * The same algorithm is used for senders.
776 */
777
778 /* pipelined_send() - send a message directly to the task waiting in
779 * sys_mq_timedreceive() (without inserting message into a queue).
780 */
781 static inline void pipelined_send(struct mqueue_inode_info *info,
782 struct msg_msg *message,
783 struct ext_wait_queue *receiver)
784 {
785 receiver->msg = message;
786 list_del(&receiver->list);
787 receiver->state = STATE_PENDING;
788 wake_up_process(receiver->task);
789 smp_wmb();
790 receiver->state = STATE_READY;
791 }
792
793 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
794 * gets its message and put to the queue (we have one free place for sure). */
795 static inline void pipelined_receive(struct mqueue_inode_info *info)
796 {
797 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
798
799 if (!sender) {
800 /* for poll */
801 wake_up_interruptible(&info->wait_q);
802 return;
803 }
804 msg_insert(sender->msg, info);
805 list_del(&sender->list);
806 sender->state = STATE_PENDING;
807 wake_up_process(sender->task);
808 smp_wmb();
809 sender->state = STATE_READY;
810 }
811
812 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
813 size_t msg_len, unsigned int msg_prio,
814 const struct timespec __user *u_abs_timeout)
815 {
816 struct file *filp;
817 struct inode *inode;
818 struct ext_wait_queue wait;
819 struct ext_wait_queue *receiver;
820 struct msg_msg *msg_ptr;
821 struct mqueue_inode_info *info;
822 long timeout;
823 int ret;
824
825 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
826 if (ret != 0)
827 return ret;
828
829 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
830 return -EINVAL;
831
832 timeout = prepare_timeout(u_abs_timeout);
833
834 ret = -EBADF;
835 filp = fget(mqdes);
836 if (unlikely(!filp))
837 goto out;
838
839 inode = filp->f_dentry->d_inode;
840 if (unlikely(filp->f_op != &mqueue_file_operations))
841 goto out_fput;
842 info = MQUEUE_I(inode);
843
844 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
845 goto out_fput;
846
847 if (unlikely(msg_len > info->attr.mq_msgsize)) {
848 ret = -EMSGSIZE;
849 goto out_fput;
850 }
851
852 /* First try to allocate memory, before doing anything with
853 * existing queues. */
854 msg_ptr = load_msg(u_msg_ptr, msg_len);
855 if (IS_ERR(msg_ptr)) {
856 ret = PTR_ERR(msg_ptr);
857 goto out_fput;
858 }
859 msg_ptr->m_ts = msg_len;
860 msg_ptr->m_type = msg_prio;
861
862 spin_lock(&info->lock);
863
864 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
865 if (filp->f_flags & O_NONBLOCK) {
866 spin_unlock(&info->lock);
867 ret = -EAGAIN;
868 } else if (unlikely(timeout < 0)) {
869 spin_unlock(&info->lock);
870 ret = timeout;
871 } else {
872 wait.task = current;
873 wait.msg = (void *) msg_ptr;
874 wait.state = STATE_NONE;
875 ret = wq_sleep(info, SEND, timeout, &wait);
876 }
877 if (ret < 0)
878 free_msg(msg_ptr);
879 } else {
880 receiver = wq_get_first_waiter(info, RECV);
881 if (receiver) {
882 pipelined_send(info, msg_ptr, receiver);
883 } else {
884 /* adds message to the queue */
885 msg_insert(msg_ptr, info);
886 __do_notify(info);
887 }
888 inode->i_atime = inode->i_mtime = inode->i_ctime =
889 CURRENT_TIME;
890 spin_unlock(&info->lock);
891 ret = 0;
892 }
893 out_fput:
894 fput(filp);
895 out:
896 return ret;
897 }
898
899 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
900 size_t msg_len, unsigned int __user *u_msg_prio,
901 const struct timespec __user *u_abs_timeout)
902 {
903 long timeout;
904 ssize_t ret;
905 struct msg_msg *msg_ptr;
906 struct file *filp;
907 struct inode *inode;
908 struct mqueue_inode_info *info;
909 struct ext_wait_queue wait;
910
911 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
912 if (ret != 0)
913 return ret;
914
915 timeout = prepare_timeout(u_abs_timeout);
916
917 ret = -EBADF;
918 filp = fget(mqdes);
919 if (unlikely(!filp))
920 goto out;
921
922 inode = filp->f_dentry->d_inode;
923 if (unlikely(filp->f_op != &mqueue_file_operations))
924 goto out_fput;
925 info = MQUEUE_I(inode);
926
927 if (unlikely(!(filp->f_mode & FMODE_READ)))
928 goto out_fput;
929
930 /* checks if buffer is big enough */
931 if (unlikely(msg_len < info->attr.mq_msgsize)) {
932 ret = -EMSGSIZE;
933 goto out_fput;
934 }
935
936 spin_lock(&info->lock);
937 if (info->attr.mq_curmsgs == 0) {
938 if (filp->f_flags & O_NONBLOCK) {
939 spin_unlock(&info->lock);
940 ret = -EAGAIN;
941 msg_ptr = NULL;
942 } else if (unlikely(timeout < 0)) {
943 spin_unlock(&info->lock);
944 ret = timeout;
945 msg_ptr = NULL;
946 } else {
947 wait.task = current;
948 wait.state = STATE_NONE;
949 ret = wq_sleep(info, RECV, timeout, &wait);
950 msg_ptr = wait.msg;
951 }
952 } else {
953 msg_ptr = msg_get(info);
954
955 inode->i_atime = inode->i_mtime = inode->i_ctime =
956 CURRENT_TIME;
957
958 /* There is now free space in queue. */
959 pipelined_receive(info);
960 spin_unlock(&info->lock);
961 ret = 0;
962 }
963 if (ret == 0) {
964 ret = msg_ptr->m_ts;
965
966 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
967 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
968 ret = -EFAULT;
969 }
970 free_msg(msg_ptr);
971 }
972 out_fput:
973 fput(filp);
974 out:
975 return ret;
976 }
977
978 /*
979 * Notes: the case when user wants us to deregister (with NULL as pointer)
980 * and he isn't currently owner of notification, will be silently discarded.
981 * It isn't explicitly defined in the POSIX.
982 */
983 asmlinkage long sys_mq_notify(mqd_t mqdes,
984 const struct sigevent __user *u_notification)
985 {
986 int ret;
987 struct file *filp;
988 struct sock *sock;
989 struct inode *inode;
990 struct sigevent notification;
991 struct mqueue_inode_info *info;
992 struct sk_buff *nc;
993
994 ret = audit_mq_notify(mqdes, u_notification);
995 if (ret != 0)
996 return ret;
997
998 nc = NULL;
999 sock = NULL;
1000 if (u_notification != NULL) {
1001 if (copy_from_user(&notification, u_notification,
1002 sizeof(struct sigevent)))
1003 return -EFAULT;
1004
1005 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1006 notification.sigev_notify != SIGEV_SIGNAL &&
1007 notification.sigev_notify != SIGEV_THREAD))
1008 return -EINVAL;
1009 if (notification.sigev_notify == SIGEV_SIGNAL &&
1010 !valid_signal(notification.sigev_signo)) {
1011 return -EINVAL;
1012 }
1013 if (notification.sigev_notify == SIGEV_THREAD) {
1014 /* create the notify skb */
1015 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1016 ret = -ENOMEM;
1017 if (!nc)
1018 goto out;
1019 ret = -EFAULT;
1020 if (copy_from_user(nc->data,
1021 notification.sigev_value.sival_ptr,
1022 NOTIFY_COOKIE_LEN)) {
1023 goto out;
1024 }
1025
1026 /* TODO: add a header? */
1027 skb_put(nc, NOTIFY_COOKIE_LEN);
1028 /* and attach it to the socket */
1029 retry:
1030 filp = fget(notification.sigev_signo);
1031 ret = -EBADF;
1032 if (!filp)
1033 goto out;
1034 sock = netlink_getsockbyfilp(filp);
1035 fput(filp);
1036 if (IS_ERR(sock)) {
1037 ret = PTR_ERR(sock);
1038 sock = NULL;
1039 goto out;
1040 }
1041
1042 ret = netlink_attachskb(sock, nc, 0,
1043 MAX_SCHEDULE_TIMEOUT, NULL);
1044 if (ret == 1)
1045 goto retry;
1046 if (ret) {
1047 sock = NULL;
1048 nc = NULL;
1049 goto out;
1050 }
1051 }
1052 }
1053
1054 ret = -EBADF;
1055 filp = fget(mqdes);
1056 if (!filp)
1057 goto out;
1058
1059 inode = filp->f_dentry->d_inode;
1060 if (unlikely(filp->f_op != &mqueue_file_operations))
1061 goto out_fput;
1062 info = MQUEUE_I(inode);
1063
1064 ret = 0;
1065 spin_lock(&info->lock);
1066 if (u_notification == NULL) {
1067 if (info->notify_owner == task_tgid(current)) {
1068 remove_notification(info);
1069 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1070 }
1071 } else if (info->notify_owner != NULL) {
1072 ret = -EBUSY;
1073 } else {
1074 switch (notification.sigev_notify) {
1075 case SIGEV_NONE:
1076 info->notify.sigev_notify = SIGEV_NONE;
1077 break;
1078 case SIGEV_THREAD:
1079 info->notify_sock = sock;
1080 info->notify_cookie = nc;
1081 sock = NULL;
1082 nc = NULL;
1083 info->notify.sigev_notify = SIGEV_THREAD;
1084 break;
1085 case SIGEV_SIGNAL:
1086 info->notify.sigev_signo = notification.sigev_signo;
1087 info->notify.sigev_value = notification.sigev_value;
1088 info->notify.sigev_notify = SIGEV_SIGNAL;
1089 break;
1090 }
1091
1092 info->notify_owner = get_pid(task_tgid(current));
1093 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1094 }
1095 spin_unlock(&info->lock);
1096 out_fput:
1097 fput(filp);
1098 out:
1099 if (sock) {
1100 netlink_detachskb(sock, nc);
1101 } else if (nc) {
1102 dev_kfree_skb(nc);
1103 }
1104 return ret;
1105 }
1106
1107 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1108 const struct mq_attr __user *u_mqstat,
1109 struct mq_attr __user *u_omqstat)
1110 {
1111 int ret;
1112 struct mq_attr mqstat, omqstat;
1113 struct file *filp;
1114 struct inode *inode;
1115 struct mqueue_inode_info *info;
1116
1117 if (u_mqstat != NULL) {
1118 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1119 return -EFAULT;
1120 if (mqstat.mq_flags & (~O_NONBLOCK))
1121 return -EINVAL;
1122 }
1123
1124 ret = -EBADF;
1125 filp = fget(mqdes);
1126 if (!filp)
1127 goto out;
1128
1129 inode = filp->f_dentry->d_inode;
1130 if (unlikely(filp->f_op != &mqueue_file_operations))
1131 goto out_fput;
1132 info = MQUEUE_I(inode);
1133
1134 spin_lock(&info->lock);
1135
1136 omqstat = info->attr;
1137 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1138 if (u_mqstat) {
1139 ret = audit_mq_getsetattr(mqdes, &mqstat);
1140 if (ret != 0)
1141 goto out;
1142 if (mqstat.mq_flags & O_NONBLOCK)
1143 filp->f_flags |= O_NONBLOCK;
1144 else
1145 filp->f_flags &= ~O_NONBLOCK;
1146
1147 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1148 }
1149
1150 spin_unlock(&info->lock);
1151
1152 ret = 0;
1153 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1154 sizeof(struct mq_attr)))
1155 ret = -EFAULT;
1156
1157 out_fput:
1158 fput(filp);
1159 out:
1160 return ret;
1161 }
1162
1163 static struct inode_operations mqueue_dir_inode_operations = {
1164 .lookup = simple_lookup,
1165 .create = mqueue_create,
1166 .unlink = mqueue_unlink,
1167 };
1168
1169 static struct file_operations mqueue_file_operations = {
1170 .flush = mqueue_flush_file,
1171 .poll = mqueue_poll_file,
1172 .read = mqueue_read_file,
1173 };
1174
1175 static struct super_operations mqueue_super_ops = {
1176 .alloc_inode = mqueue_alloc_inode,
1177 .destroy_inode = mqueue_destroy_inode,
1178 .statfs = simple_statfs,
1179 .delete_inode = mqueue_delete_inode,
1180 .drop_inode = generic_delete_inode,
1181 };
1182
1183 static struct file_system_type mqueue_fs_type = {
1184 .name = "mqueue",
1185 .get_sb = mqueue_get_sb,
1186 .kill_sb = kill_litter_super,
1187 };
1188
1189 static int msg_max_limit_min = DFLT_MSGMAX;
1190 static int msg_max_limit_max = HARD_MSGMAX;
1191
1192 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1193 static int msg_maxsize_limit_max = INT_MAX;
1194
1195 static ctl_table mq_sysctls[] = {
1196 {
1197 .ctl_name = CTL_QUEUESMAX,
1198 .procname = "queues_max",
1199 .data = &queues_max,
1200 .maxlen = sizeof(int),
1201 .mode = 0644,
1202 .proc_handler = &proc_dointvec,
1203 },
1204 {
1205 .ctl_name = CTL_MSGMAX,
1206 .procname = "msg_max",
1207 .data = &msg_max,
1208 .maxlen = sizeof(int),
1209 .mode = 0644,
1210 .proc_handler = &proc_dointvec_minmax,
1211 .extra1 = &msg_max_limit_min,
1212 .extra2 = &msg_max_limit_max,
1213 },
1214 {
1215 .ctl_name = CTL_MSGSIZEMAX,
1216 .procname = "msgsize_max",
1217 .data = &msgsize_max,
1218 .maxlen = sizeof(int),
1219 .mode = 0644,
1220 .proc_handler = &proc_dointvec_minmax,
1221 .extra1 = &msg_maxsize_limit_min,
1222 .extra2 = &msg_maxsize_limit_max,
1223 },
1224 { .ctl_name = 0 }
1225 };
1226
1227 static ctl_table mq_sysctl_dir[] = {
1228 {
1229 .ctl_name = FS_MQUEUE,
1230 .procname = "mqueue",
1231 .mode = 0555,
1232 .child = mq_sysctls,
1233 },
1234 { .ctl_name = 0 }
1235 };
1236
1237 static ctl_table mq_sysctl_root[] = {
1238 {
1239 .ctl_name = CTL_FS,
1240 .procname = "fs",
1241 .mode = 0555,
1242 .child = mq_sysctl_dir,
1243 },
1244 { .ctl_name = 0 }
1245 };
1246
1247 static int __init init_mqueue_fs(void)
1248 {
1249 int error;
1250
1251 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1252 sizeof(struct mqueue_inode_info), 0,
1253 SLAB_HWCACHE_ALIGN, init_once, NULL);
1254 if (mqueue_inode_cachep == NULL)
1255 return -ENOMEM;
1256
1257 /* ignore failues - they are not fatal */
1258 mq_sysctl_table = register_sysctl_table(mq_sysctl_root, 0);
1259
1260 error = register_filesystem(&mqueue_fs_type);
1261 if (error)
1262 goto out_sysctl;
1263
1264 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1265 error = PTR_ERR(mqueue_mnt);
1266 goto out_filesystem;
1267 }
1268
1269 /* internal initialization - not common for vfs */
1270 queues_count = 0;
1271 spin_lock_init(&mq_lock);
1272
1273 return 0;
1274
1275 out_filesystem:
1276 unregister_filesystem(&mqueue_fs_type);
1277 out_sysctl:
1278 if (mq_sysctl_table)
1279 unregister_sysctl_table(mq_sysctl_table);
1280 kmem_cache_destroy(mqueue_inode_cachep);
1281 return error;
1282 }
1283
1284 __initcall(init_mqueue_fs);
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