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locks: add warning about mandatory locking races
[pv_ops_mirror.git] / ipc / mqueue.c
blob145d5a0d299f77d8cb328b9deb292f55c69f5a7d
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 const struct inode_operations mqueue_dir_inode_operations;
88 static const 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 struct kmem_cache *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, struct kmem_cache * cachep, unsigned long flags)
215 {
216 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
217
218 inode_init_once(&p->vfs_inode);
219 }
220
221 static struct inode *mqueue_alloc_inode(struct super_block *sb)
222 {
223 struct mqueue_inode_info *ei;
224
225 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
226 if (!ei)
227 return NULL;
228 return &ei->vfs_inode;
229 }
230
231 static void mqueue_destroy_inode(struct inode *inode)
232 {
233 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
234 }
235
236 static void mqueue_delete_inode(struct inode *inode)
237 {
238 struct mqueue_inode_info *info;
239 struct user_struct *user;
240 unsigned long mq_bytes;
241 int i;
242
243 if (S_ISDIR(inode->i_mode)) {
244 clear_inode(inode);
245 return;
246 }
247 info = MQUEUE_I(inode);
248 spin_lock(&info->lock);
249 for (i = 0; i < info->attr.mq_curmsgs; i++)
250 free_msg(info->messages[i]);
251 kfree(info->messages);
252 spin_unlock(&info->lock);
253
254 clear_inode(inode);
255
256 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
257 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
258 user = info->user;
259 if (user) {
260 spin_lock(&mq_lock);
261 user->mq_bytes -= mq_bytes;
262 queues_count--;
263 spin_unlock(&mq_lock);
264 free_uid(user);
265 }
266 }
267
268 static int mqueue_create(struct inode *dir, struct dentry *dentry,
269 int mode, struct nameidata *nd)
270 {
271 struct inode *inode;
272 struct mq_attr *attr = dentry->d_fsdata;
273 int error;
274
275 spin_lock(&mq_lock);
276 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
277 error = -ENOSPC;
278 goto out_lock;
279 }
280 queues_count++;
281 spin_unlock(&mq_lock);
282
283 inode = mqueue_get_inode(dir->i_sb, mode, attr);
284 if (!inode) {
285 error = -ENOMEM;
286 spin_lock(&mq_lock);
287 queues_count--;
288 goto out_lock;
289 }
290
291 dir->i_size += DIRENT_SIZE;
292 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
293
294 d_instantiate(dentry, inode);
295 dget(dentry);
296 return 0;
297 out_lock:
298 spin_unlock(&mq_lock);
299 return error;
300 }
301
302 static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
303 {
304 struct inode *inode = dentry->d_inode;
305
306 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
307 dir->i_size -= DIRENT_SIZE;
308 drop_nlink(inode);
309 dput(dentry);
310 return 0;
311 }
312
313 /*
314 * This is routine for system read from queue file.
315 * To avoid mess with doing here some sort of mq_receive we allow
316 * to read only queue size & notification info (the only values
317 * that are interesting from user point of view and aren't accessible
318 * through std routines)
319 */
320 static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
321 size_t count, loff_t * off)
322 {
323 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
324 char buffer[FILENT_SIZE];
325 size_t slen;
326 loff_t o;
327
328 if (!count)
329 return 0;
330
331 spin_lock(&info->lock);
332 snprintf(buffer, sizeof(buffer),
333 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
334 info->qsize,
335 info->notify_owner ? info->notify.sigev_notify : 0,
336 (info->notify_owner &&
337 info->notify.sigev_notify == SIGEV_SIGNAL) ?
338 info->notify.sigev_signo : 0,
339 pid_nr(info->notify_owner));
340 spin_unlock(&info->lock);
341 buffer[sizeof(buffer)-1] = '\0';
342 slen = strlen(buffer)+1;
343
344 o = *off;
345 if (o > slen)
346 return 0;
347
348 if (o + count > slen)
349 count = slen - o;
350
351 if (copy_to_user(u_data, buffer + o, count))
352 return -EFAULT;
353
354 *off = o + count;
355 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
356 return count;
357 }
358
359 static int mqueue_flush_file(struct file *filp, fl_owner_t id)
360 {
361 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
362
363 spin_lock(&info->lock);
364 if (task_tgid(current) == info->notify_owner)
365 remove_notification(info);
366
367 spin_unlock(&info->lock);
368 return 0;
369 }
370
371 static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
372 {
373 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
374 int retval = 0;
375
376 poll_wait(filp, &info->wait_q, poll_tab);
377
378 spin_lock(&info->lock);
379 if (info->attr.mq_curmsgs)
380 retval = POLLIN | POLLRDNORM;
381
382 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
383 retval |= POLLOUT | POLLWRNORM;
384 spin_unlock(&info->lock);
385
386 return retval;
387 }
388
389 /* Adds current to info->e_wait_q[sr] before element with smaller prio */
390 static void wq_add(struct mqueue_inode_info *info, int sr,
391 struct ext_wait_queue *ewp)
392 {
393 struct ext_wait_queue *walk;
394
395 ewp->task = current;
396
397 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
398 if (walk->task->static_prio <= current->static_prio) {
399 list_add_tail(&ewp->list, &walk->list);
400 return;
401 }
402 }
403 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
404 }
405
406 /*
407 * Puts current task to sleep. Caller must hold queue lock. After return
408 * lock isn't held.
409 * sr: SEND or RECV
410 */
411 static int wq_sleep(struct mqueue_inode_info *info, int sr,
412 long timeout, struct ext_wait_queue *ewp)
413 {
414 int retval;
415 signed long time;
416
417 wq_add(info, sr, ewp);
418
419 for (;;) {
420 set_current_state(TASK_INTERRUPTIBLE);
421
422 spin_unlock(&info->lock);
423 time = schedule_timeout(timeout);
424
425 while (ewp->state == STATE_PENDING)
426 cpu_relax();
427
428 if (ewp->state == STATE_READY) {
429 retval = 0;
430 goto out;
431 }
432 spin_lock(&info->lock);
433 if (ewp->state == STATE_READY) {
434 retval = 0;
435 goto out_unlock;
436 }
437 if (signal_pending(current)) {
438 retval = -ERESTARTSYS;
439 break;
440 }
441 if (time == 0) {
442 retval = -ETIMEDOUT;
443 break;
444 }
445 }
446 list_del(&ewp->list);
447 out_unlock:
448 spin_unlock(&info->lock);
449 out:
450 return retval;
451 }
452
453 /*
454 * Returns waiting task that should be serviced first or NULL if none exists
455 */
456 static struct ext_wait_queue *wq_get_first_waiter(
457 struct mqueue_inode_info *info, int sr)
458 {
459 struct list_head *ptr;
460
461 ptr = info->e_wait_q[sr].list.prev;
462 if (ptr == &info->e_wait_q[sr].list)
463 return NULL;
464 return list_entry(ptr, struct ext_wait_queue, list);
465 }
466
467 /* Auxiliary functions to manipulate messages' list */
468 static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
469 {
470 int k;
471
472 k = info->attr.mq_curmsgs - 1;
473 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
474 info->messages[k + 1] = info->messages[k];
475 k--;
476 }
477 info->attr.mq_curmsgs++;
478 info->qsize += ptr->m_ts;
479 info->messages[k + 1] = ptr;
480 }
481
482 static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
483 {
484 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
485 return info->messages[info->attr.mq_curmsgs];
486 }
487
488 static inline void set_cookie(struct sk_buff *skb, char code)
489 {
490 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
491 }
492
493 /*
494 * The next function is only to split too long sys_mq_timedsend
495 */
496 static void __do_notify(struct mqueue_inode_info *info)
497 {
498 /* notification
499 * invoked when there is registered process and there isn't process
500 * waiting synchronously for message AND state of queue changed from
501 * empty to not empty. Here we are sure that no one is waiting
502 * synchronously. */
503 if (info->notify_owner &&
504 info->attr.mq_curmsgs == 1) {
505 struct siginfo sig_i;
506 switch (info->notify.sigev_notify) {
507 case SIGEV_NONE:
508 break;
509 case SIGEV_SIGNAL:
510 /* sends signal */
511
512 sig_i.si_signo = info->notify.sigev_signo;
513 sig_i.si_errno = 0;
514 sig_i.si_code = SI_MESGQ;
515 sig_i.si_value = info->notify.sigev_value;
516 sig_i.si_pid = current->tgid;
517 sig_i.si_uid = current->uid;
518
519 kill_pid_info(info->notify.sigev_signo,
520 &sig_i, info->notify_owner);
521 break;
522 case SIGEV_THREAD:
523 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
524 netlink_sendskb(info->notify_sock,
525 info->notify_cookie, 0);
526 break;
527 }
528 /* after notification unregisters process */
529 put_pid(info->notify_owner);
530 info->notify_owner = NULL;
531 }
532 wake_up(&info->wait_q);
533 }
534
535 static long prepare_timeout(const struct timespec __user *u_arg)
536 {
537 struct timespec ts, nowts;
538 long timeout;
539
540 if (u_arg) {
541 if (unlikely(copy_from_user(&ts, u_arg,
542 sizeof(struct timespec))))
543 return -EFAULT;
544
545 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
546 || ts.tv_nsec >= NSEC_PER_SEC))
547 return -EINVAL;
548 nowts = CURRENT_TIME;
549 /* first subtract as jiffies can't be too big */
550 ts.tv_sec -= nowts.tv_sec;
551 if (ts.tv_nsec < nowts.tv_nsec) {
552 ts.tv_nsec += NSEC_PER_SEC;
553 ts.tv_sec--;
554 }
555 ts.tv_nsec -= nowts.tv_nsec;
556 if (ts.tv_sec < 0)
557 return 0;
558
559 timeout = timespec_to_jiffies(&ts) + 1;
560 } else
561 return MAX_SCHEDULE_TIMEOUT;
562
563 return timeout;
564 }
565
566 static void remove_notification(struct mqueue_inode_info *info)
567 {
568 if (info->notify_owner != NULL &&
569 info->notify.sigev_notify == SIGEV_THREAD) {
570 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
571 netlink_sendskb(info->notify_sock, info->notify_cookie, 0);
572 }
573 put_pid(info->notify_owner);
574 info->notify_owner = NULL;
575 }
576
577 static int mq_attr_ok(struct mq_attr *attr)
578 {
579 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
580 return 0;
581 if (capable(CAP_SYS_RESOURCE)) {
582 if (attr->mq_maxmsg > HARD_MSGMAX)
583 return 0;
584 } else {
585 if (attr->mq_maxmsg > msg_max ||
586 attr->mq_msgsize > msgsize_max)
587 return 0;
588 }
589 /* check for overflow */
590 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
591 return 0;
592 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
593 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
594 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
595 return 0;
596 return 1;
597 }
598
599 /*
600 * Invoked when creating a new queue via sys_mq_open
601 */
602 static struct file *do_create(struct dentry *dir, struct dentry *dentry,
603 int oflag, mode_t mode, struct mq_attr __user *u_attr)
604 {
605 struct mq_attr attr;
606 int ret;
607
608 if (u_attr) {
609 ret = -EFAULT;
610 if (copy_from_user(&attr, u_attr, sizeof(attr)))
611 goto out;
612 ret = -EINVAL;
613 if (!mq_attr_ok(&attr))
614 goto out;
615 /* store for use during create */
616 dentry->d_fsdata = &attr;
617 }
618
619 mode &= ~current->fs->umask;
620 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
621 dentry->d_fsdata = NULL;
622 if (ret)
623 goto out;
624
625 return dentry_open(dentry, mqueue_mnt, oflag);
626
627 out:
628 dput(dentry);
629 mntput(mqueue_mnt);
630 return ERR_PTR(ret);
631 }
632
633 /* Opens existing queue */
634 static struct file *do_open(struct dentry *dentry, int oflag)
635 {
636 static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
637 MAY_READ | MAY_WRITE };
638
639 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
640 dput(dentry);
641 mntput(mqueue_mnt);
642 return ERR_PTR(-EINVAL);
643 }
644
645 if (permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE], NULL)) {
646 dput(dentry);
647 mntput(mqueue_mnt);
648 return ERR_PTR(-EACCES);
649 }
650
651 return dentry_open(dentry, mqueue_mnt, oflag);
652 }
653
654 asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
655 struct mq_attr __user *u_attr)
656 {
657 struct dentry *dentry;
658 struct file *filp;
659 char *name;
660 int fd, error;
661
662 error = audit_mq_open(oflag, mode, u_attr);
663 if (error != 0)
664 return error;
665
666 if (IS_ERR(name = getname(u_name)))
667 return PTR_ERR(name);
668
669 fd = get_unused_fd();
670 if (fd < 0)
671 goto out_putname;
672
673 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
674 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
675 if (IS_ERR(dentry)) {
676 error = PTR_ERR(dentry);
677 goto out_err;
678 }
679 mntget(mqueue_mnt);
680
681 if (oflag & O_CREAT) {
682 if (dentry->d_inode) { /* entry already exists */
683 audit_inode(name, dentry->d_inode);
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 audit_inode(name, dentry->d_inode);
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_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
735 I_MUTEX_PARENT);
736 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
737 if (IS_ERR(dentry)) {
738 err = PTR_ERR(dentry);
739 goto out_unlock;
740 }
741
742 if (!dentry->d_inode) {
743 err = -ENOENT;
744 goto out_err;
745 }
746
747 inode = dentry->d_inode;
748 if (inode)
749 atomic_inc(&inode->i_count);
750
751 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
752 out_err:
753 dput(dentry);
754
755 out_unlock:
756 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
757 putname(name);
758 if (inode)
759 iput(inode);
760
761 return err;
762 }
763
764 /* Pipelined send and receive functions.
765 *
766 * If a receiver finds no waiting message, then it registers itself in the
767 * list of waiting receivers. A sender checks that list before adding the new
768 * message into the message array. If there is a waiting receiver, then it
769 * bypasses the message array and directly hands the message over to the
770 * receiver.
771 * The receiver accepts the message and returns without grabbing the queue
772 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
773 * are necessary. The same algorithm is used for sysv semaphores, see
774 * ipc/sem.c for more details.
775 *
776 * The same algorithm is used for senders.
777 */
778
779 /* pipelined_send() - send a message directly to the task waiting in
780 * sys_mq_timedreceive() (without inserting message into a queue).
781 */
782 static inline void pipelined_send(struct mqueue_inode_info *info,
783 struct msg_msg *message,
784 struct ext_wait_queue *receiver)
785 {
786 receiver->msg = message;
787 list_del(&receiver->list);
788 receiver->state = STATE_PENDING;
789 wake_up_process(receiver->task);
790 smp_wmb();
791 receiver->state = STATE_READY;
792 }
793
794 /* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
795 * gets its message and put to the queue (we have one free place for sure). */
796 static inline void pipelined_receive(struct mqueue_inode_info *info)
797 {
798 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
799
800 if (!sender) {
801 /* for poll */
802 wake_up_interruptible(&info->wait_q);
803 return;
804 }
805 msg_insert(sender->msg, info);
806 list_del(&sender->list);
807 sender->state = STATE_PENDING;
808 wake_up_process(sender->task);
809 smp_wmb();
810 sender->state = STATE_READY;
811 }
812
813 asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
814 size_t msg_len, unsigned int msg_prio,
815 const struct timespec __user *u_abs_timeout)
816 {
817 struct file *filp;
818 struct inode *inode;
819 struct ext_wait_queue wait;
820 struct ext_wait_queue *receiver;
821 struct msg_msg *msg_ptr;
822 struct mqueue_inode_info *info;
823 long timeout;
824 int ret;
825
826 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
827 if (ret != 0)
828 return ret;
829
830 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
831 return -EINVAL;
832
833 timeout = prepare_timeout(u_abs_timeout);
834
835 ret = -EBADF;
836 filp = fget(mqdes);
837 if (unlikely(!filp))
838 goto out;
839
840 inode = filp->f_path.dentry->d_inode;
841 if (unlikely(filp->f_op != &mqueue_file_operations))
842 goto out_fput;
843 info = MQUEUE_I(inode);
844 audit_inode(NULL, inode);
845
846 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
847 goto out_fput;
848
849 if (unlikely(msg_len > info->attr.mq_msgsize)) {
850 ret = -EMSGSIZE;
851 goto out_fput;
852 }
853
854 /* First try to allocate memory, before doing anything with
855 * existing queues. */
856 msg_ptr = load_msg(u_msg_ptr, msg_len);
857 if (IS_ERR(msg_ptr)) {
858 ret = PTR_ERR(msg_ptr);
859 goto out_fput;
860 }
861 msg_ptr->m_ts = msg_len;
862 msg_ptr->m_type = msg_prio;
863
864 spin_lock(&info->lock);
865
866 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
867 if (filp->f_flags & O_NONBLOCK) {
868 spin_unlock(&info->lock);
869 ret = -EAGAIN;
870 } else if (unlikely(timeout < 0)) {
871 spin_unlock(&info->lock);
872 ret = timeout;
873 } else {
874 wait.task = current;
875 wait.msg = (void *) msg_ptr;
876 wait.state = STATE_NONE;
877 ret = wq_sleep(info, SEND, timeout, &wait);
878 }
879 if (ret < 0)
880 free_msg(msg_ptr);
881 } else {
882 receiver = wq_get_first_waiter(info, RECV);
883 if (receiver) {
884 pipelined_send(info, msg_ptr, receiver);
885 } else {
886 /* adds message to the queue */
887 msg_insert(msg_ptr, info);
888 __do_notify(info);
889 }
890 inode->i_atime = inode->i_mtime = inode->i_ctime =
891 CURRENT_TIME;
892 spin_unlock(&info->lock);
893 ret = 0;
894 }
895 out_fput:
896 fput(filp);
897 out:
898 return ret;
899 }
900
901 asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
902 size_t msg_len, unsigned int __user *u_msg_prio,
903 const struct timespec __user *u_abs_timeout)
904 {
905 long timeout;
906 ssize_t ret;
907 struct msg_msg *msg_ptr;
908 struct file *filp;
909 struct inode *inode;
910 struct mqueue_inode_info *info;
911 struct ext_wait_queue wait;
912
913 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
914 if (ret != 0)
915 return ret;
916
917 timeout = prepare_timeout(u_abs_timeout);
918
919 ret = -EBADF;
920 filp = fget(mqdes);
921 if (unlikely(!filp))
922 goto out;
923
924 inode = filp->f_path.dentry->d_inode;
925 if (unlikely(filp->f_op != &mqueue_file_operations))
926 goto out_fput;
927 info = MQUEUE_I(inode);
928 audit_inode(NULL, inode);
929
930 if (unlikely(!(filp->f_mode & FMODE_READ)))
931 goto out_fput;
932
933 /* checks if buffer is big enough */
934 if (unlikely(msg_len < info->attr.mq_msgsize)) {
935 ret = -EMSGSIZE;
936 goto out_fput;
937 }
938
939 spin_lock(&info->lock);
940 if (info->attr.mq_curmsgs == 0) {
941 if (filp->f_flags & O_NONBLOCK) {
942 spin_unlock(&info->lock);
943 ret = -EAGAIN;
944 msg_ptr = NULL;
945 } else if (unlikely(timeout < 0)) {
946 spin_unlock(&info->lock);
947 ret = timeout;
948 msg_ptr = NULL;
949 } else {
950 wait.task = current;
951 wait.state = STATE_NONE;
952 ret = wq_sleep(info, RECV, timeout, &wait);
953 msg_ptr = wait.msg;
954 }
955 } else {
956 msg_ptr = msg_get(info);
957
958 inode->i_atime = inode->i_mtime = inode->i_ctime =
959 CURRENT_TIME;
960
961 /* There is now free space in queue. */
962 pipelined_receive(info);
963 spin_unlock(&info->lock);
964 ret = 0;
965 }
966 if (ret == 0) {
967 ret = msg_ptr->m_ts;
968
969 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
970 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
971 ret = -EFAULT;
972 }
973 free_msg(msg_ptr);
974 }
975 out_fput:
976 fput(filp);
977 out:
978 return ret;
979 }
980
981 /*
982 * Notes: the case when user wants us to deregister (with NULL as pointer)
983 * and he isn't currently owner of notification, will be silently discarded.
984 * It isn't explicitly defined in the POSIX.
985 */
986 asmlinkage long sys_mq_notify(mqd_t mqdes,
987 const struct sigevent __user *u_notification)
988 {
989 int ret;
990 struct file *filp;
991 struct sock *sock;
992 struct inode *inode;
993 struct sigevent notification;
994 struct mqueue_inode_info *info;
995 struct sk_buff *nc;
996
997 ret = audit_mq_notify(mqdes, u_notification);
998 if (ret != 0)
999 return ret;
1000
1001 nc = NULL;
1002 sock = NULL;
1003 if (u_notification != NULL) {
1004 if (copy_from_user(&notification, u_notification,
1005 sizeof(struct sigevent)))
1006 return -EFAULT;
1007
1008 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1009 notification.sigev_notify != SIGEV_SIGNAL &&
1010 notification.sigev_notify != SIGEV_THREAD))
1011 return -EINVAL;
1012 if (notification.sigev_notify == SIGEV_SIGNAL &&
1013 !valid_signal(notification.sigev_signo)) {
1014 return -EINVAL;
1015 }
1016 if (notification.sigev_notify == SIGEV_THREAD) {
1017 /* create the notify skb */
1018 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1019 ret = -ENOMEM;
1020 if (!nc)
1021 goto out;
1022 ret = -EFAULT;
1023 if (copy_from_user(nc->data,
1024 notification.sigev_value.sival_ptr,
1025 NOTIFY_COOKIE_LEN)) {
1026 goto out;
1027 }
1028
1029 /* TODO: add a header? */
1030 skb_put(nc, NOTIFY_COOKIE_LEN);
1031 /* and attach it to the socket */
1032 retry:
1033 filp = fget(notification.sigev_signo);
1034 ret = -EBADF;
1035 if (!filp)
1036 goto out;
1037 sock = netlink_getsockbyfilp(filp);
1038 fput(filp);
1039 if (IS_ERR(sock)) {
1040 ret = PTR_ERR(sock);
1041 sock = NULL;
1042 goto out;
1043 }
1044
1045 ret = netlink_attachskb(sock, nc, 0,
1046 MAX_SCHEDULE_TIMEOUT, NULL);
1047 if (ret == 1)
1048 goto retry;
1049 if (ret) {
1050 sock = NULL;
1051 nc = NULL;
1052 goto out;
1053 }
1054 }
1055 }
1056
1057 ret = -EBADF;
1058 filp = fget(mqdes);
1059 if (!filp)
1060 goto out;
1061
1062 inode = filp->f_path.dentry->d_inode;
1063 if (unlikely(filp->f_op != &mqueue_file_operations))
1064 goto out_fput;
1065 info = MQUEUE_I(inode);
1066
1067 ret = 0;
1068 spin_lock(&info->lock);
1069 if (u_notification == NULL) {
1070 if (info->notify_owner == task_tgid(current)) {
1071 remove_notification(info);
1072 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1073 }
1074 } else if (info->notify_owner != NULL) {
1075 ret = -EBUSY;
1076 } else {
1077 switch (notification.sigev_notify) {
1078 case SIGEV_NONE:
1079 info->notify.sigev_notify = SIGEV_NONE;
1080 break;
1081 case SIGEV_THREAD:
1082 info->notify_sock = sock;
1083 info->notify_cookie = nc;
1084 sock = NULL;
1085 nc = NULL;
1086 info->notify.sigev_notify = SIGEV_THREAD;
1087 break;
1088 case SIGEV_SIGNAL:
1089 info->notify.sigev_signo = notification.sigev_signo;
1090 info->notify.sigev_value = notification.sigev_value;
1091 info->notify.sigev_notify = SIGEV_SIGNAL;
1092 break;
1093 }
1094
1095 info->notify_owner = get_pid(task_tgid(current));
1096 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1097 }
1098 spin_unlock(&info->lock);
1099 out_fput:
1100 fput(filp);
1101 out:
1102 if (sock) {
1103 netlink_detachskb(sock, nc);
1104 } else if (nc) {
1105 dev_kfree_skb(nc);
1106 }
1107 return ret;
1108 }
1109
1110 asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1111 const struct mq_attr __user *u_mqstat,
1112 struct mq_attr __user *u_omqstat)
1113 {
1114 int ret;
1115 struct mq_attr mqstat, omqstat;
1116 struct file *filp;
1117 struct inode *inode;
1118 struct mqueue_inode_info *info;
1119
1120 if (u_mqstat != NULL) {
1121 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1122 return -EFAULT;
1123 if (mqstat.mq_flags & (~O_NONBLOCK))
1124 return -EINVAL;
1125 }
1126
1127 ret = -EBADF;
1128 filp = fget(mqdes);
1129 if (!filp)
1130 goto out;
1131
1132 inode = filp->f_path.dentry->d_inode;
1133 if (unlikely(filp->f_op != &mqueue_file_operations))
1134 goto out_fput;
1135 info = MQUEUE_I(inode);
1136
1137 spin_lock(&info->lock);
1138
1139 omqstat = info->attr;
1140 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1141 if (u_mqstat) {
1142 ret = audit_mq_getsetattr(mqdes, &mqstat);
1143 if (ret != 0)
1144 goto out;
1145 if (mqstat.mq_flags & O_NONBLOCK)
1146 filp->f_flags |= O_NONBLOCK;
1147 else
1148 filp->f_flags &= ~O_NONBLOCK;
1149
1150 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1151 }
1152
1153 spin_unlock(&info->lock);
1154
1155 ret = 0;
1156 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1157 sizeof(struct mq_attr)))
1158 ret = -EFAULT;
1159
1160 out_fput:
1161 fput(filp);
1162 out:
1163 return ret;
1164 }
1165
1166 static const struct inode_operations mqueue_dir_inode_operations = {
1167 .lookup = simple_lookup,
1168 .create = mqueue_create,
1169 .unlink = mqueue_unlink,
1170 };
1171
1172 static const struct file_operations mqueue_file_operations = {
1173 .flush = mqueue_flush_file,
1174 .poll = mqueue_poll_file,
1175 .read = mqueue_read_file,
1176 };
1177
1178 static struct super_operations mqueue_super_ops = {
1179 .alloc_inode = mqueue_alloc_inode,
1180 .destroy_inode = mqueue_destroy_inode,
1181 .statfs = simple_statfs,
1182 .delete_inode = mqueue_delete_inode,
1183 .drop_inode = generic_delete_inode,
1184 };
1185
1186 static struct file_system_type mqueue_fs_type = {
1187 .name = "mqueue",
1188 .get_sb = mqueue_get_sb,
1189 .kill_sb = kill_litter_super,
1190 };
1191
1192 static int msg_max_limit_min = DFLT_MSGMAX;
1193 static int msg_max_limit_max = HARD_MSGMAX;
1194
1195 static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1196 static int msg_maxsize_limit_max = INT_MAX;
1197
1198 static ctl_table mq_sysctls[] = {
1199 {
1200 .ctl_name = CTL_QUEUESMAX,
1201 .procname = "queues_max",
1202 .data = &queues_max,
1203 .maxlen = sizeof(int),
1204 .mode = 0644,
1205 .proc_handler = &proc_dointvec,
1206 },
1207 {
1208 .ctl_name = CTL_MSGMAX,
1209 .procname = "msg_max",
1210 .data = &msg_max,
1211 .maxlen = sizeof(int),
1212 .mode = 0644,
1213 .proc_handler = &proc_dointvec_minmax,
1214 .extra1 = &msg_max_limit_min,
1215 .extra2 = &msg_max_limit_max,
1216 },
1217 {
1218 .ctl_name = CTL_MSGSIZEMAX,
1219 .procname = "msgsize_max",
1220 .data = &msgsize_max,
1221 .maxlen = sizeof(int),
1222 .mode = 0644,
1223 .proc_handler = &proc_dointvec_minmax,
1224 .extra1 = &msg_maxsize_limit_min,
1225 .extra2 = &msg_maxsize_limit_max,
1226 },
1227 { .ctl_name = 0 }
1228 };
1229
1230 static ctl_table mq_sysctl_dir[] = {
1231 {
1232 .ctl_name = FS_MQUEUE,
1233 .procname = "mqueue",
1234 .mode = 0555,
1235 .child = mq_sysctls,
1236 },
1237 { .ctl_name = 0 }
1238 };
1239
1240 static ctl_table mq_sysctl_root[] = {
1241 {
1242 .ctl_name = CTL_FS,
1243 .procname = "fs",
1244 .mode = 0555,
1245 .child = mq_sysctl_dir,
1246 },
1247 { .ctl_name = 0 }
1248 };
1249
1250 static int __init init_mqueue_fs(void)
1251 {
1252 int error;
1253
1254 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1255 sizeof(struct mqueue_inode_info), 0,
1256 SLAB_HWCACHE_ALIGN, init_once);
1257 if (mqueue_inode_cachep == NULL)
1258 return -ENOMEM;
1259
1260 /* ignore failues - they are not fatal */
1261 mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1262
1263 error = register_filesystem(&mqueue_fs_type);
1264 if (error)
1265 goto out_sysctl;
1266
1267 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1268 error = PTR_ERR(mqueue_mnt);
1269 goto out_filesystem;
1270 }
1271
1272 /* internal initialization - not common for vfs */
1273 queues_count = 0;
1274 spin_lock_init(&mq_lock);
1275
1276 return 0;
1277
1278 out_filesystem:
1279 unregister_filesystem(&mqueue_fs_type);
1280 out_sysctl:
1281 if (mq_sysctl_table)
1282 unregister_sysctl_table(mq_sysctl_table);
1283 kmem_cache_destroy(mqueue_inode_cachep);
1284 return error;
1285 }
1286
1287 __initcall(init_mqueue_fs);
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