projects/linux·blob v2.6.21 · refs

1285 lines · 29.9 KiB

1/*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004 Krzysztof Benedyczak ([email protected])
5 * Michal Wronski ([email protected])
6 *
7 * Spinlocks: Mohamed Abbas ([email protected])
8 * Lockless receive & send, fd based notify:
9 * Manfred Spraul ([email protected])
10 *
11 * Audit: George Wilson ([email protected])
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
60struct 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
67struct 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
87static const struct inode_operations mqueue_dir_inode_operations;
88static const struct file_operations mqueue_file_operations;
89static struct super_operations mqueue_super_ops;
90static void remove_notification(struct mqueue_inode_info *info);
91
92static spinlock_t mq_lock;
93static struct kmem_cache *mqueue_inode_cachep;
94static struct vfsmount *mqueue_mnt;
95
96static unsigned int queues_count;
97static unsigned int queues_max = DFLT_QUEUESMAX;
98static unsigned int msg_max = DFLT_MSGMAX;
99static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
100
101static struct ctl_table_header * mq_sysctl_table;
102
103static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
104{
105 return container_of(inode, struct mqueue_inode_info, vfs_inode);
106}
107
108static 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;
179out_inode:
180 make_bad_inode(inode);
181 iput(inode);
182 return NULL;
183}
184
185static 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
207static 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
214static 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 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
219 SLAB_CTOR_CONSTRUCTOR)
220 inode_init_once(&p->vfs_inode);
221}
222
223static 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, GFP_KERNEL);
228 if (!ei)
229 return NULL;
230 return &ei->vfs_inode;
231}
232
233static void mqueue_destroy_inode(struct inode *inode)
234{
235 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
236}
237
238static 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
270static 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;
299out_lock:
300 spin_unlock(&mq_lock);
301 return error;
302}
303
304static 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*/
322static 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_path.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_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
358 return count;
359}
360
361static int mqueue_flush_file(struct file *filp, fl_owner_t id)
362{
363 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.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
373static 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_path.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 */
392static 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 */
413static 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);
449out_unlock:
450 spin_unlock(&info->lock);
451out:
452 return retval;
453}
454
455/*
456 * Returns waiting task that should be serviced first or NULL if none exists
457 */
458static 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 */
470static 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
484static 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
490static 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 */
498static 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
537static 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
568static 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
579static 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 */
604static 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
629out:
630 dput(dentry);
631 mntput(mqueue_mnt);
632 return ERR_PTR(ret);
633}
634
635/* Opens existing queue */
636static struct file *do_open(struct dentry *dentry, int oflag)
637{
638static 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
656asmlinkage 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
709out:
710 dput(dentry);
711 mntput(mqueue_mnt);
712out_putfd:
713 put_unused_fd(fd);
714out_err:
715 fd = error;
716out_upsem:
717 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
718out_putname:
719 putname(name);
720 return fd;
721}
722
723asmlinkage 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);
752out_err:
753 dput(dentry);
754
755out_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 */
782static 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). */
796static 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
813asmlinkage 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
845 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
846 goto out_fput;
847
848 if (unlikely(msg_len > info->attr.mq_msgsize)) {
849 ret = -EMSGSIZE;
850 goto out_fput;
851 }
852
853 /* First try to allocate memory, before doing anything with
854 * existing queues. */
855 msg_ptr = load_msg(u_msg_ptr, msg_len);
856 if (IS_ERR(msg_ptr)) {
857 ret = PTR_ERR(msg_ptr);
858 goto out_fput;
859 }
860 msg_ptr->m_ts = msg_len;
861 msg_ptr->m_type = msg_prio;
862
863 spin_lock(&info->lock);
864
865 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
866 if (filp->f_flags & O_NONBLOCK) {
867 spin_unlock(&info->lock);
868 ret = -EAGAIN;
869 } else if (unlikely(timeout < 0)) {
870 spin_unlock(&info->lock);
871 ret = timeout;
872 } else {
873 wait.task = current;
874 wait.msg = (void *) msg_ptr;
875 wait.state = STATE_NONE;
876 ret = wq_sleep(info, SEND, timeout, &wait);
877 }
878 if (ret < 0)
879 free_msg(msg_ptr);
880 } else {
881 receiver = wq_get_first_waiter(info, RECV);
882 if (receiver) {
883 pipelined_send(info, msg_ptr, receiver);
884 } else {
885 /* adds message to the queue */
886 msg_insert(msg_ptr, info);
887 __do_notify(info);
888 }
889 inode->i_atime = inode->i_mtime = inode->i_ctime =
890 CURRENT_TIME;
891 spin_unlock(&info->lock);
892 ret = 0;
893 }
894out_fput:
895 fput(filp);
896out:
897 return ret;
898}
899
900asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
901 size_t msg_len, unsigned int __user *u_msg_prio,
902 const struct timespec __user *u_abs_timeout)
903{
904 long timeout;
905 ssize_t ret;
906 struct msg_msg *msg_ptr;
907 struct file *filp;
908 struct inode *inode;
909 struct mqueue_inode_info *info;
910 struct ext_wait_queue wait;
911
912 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
913 if (ret != 0)
914 return ret;
915
916 timeout = prepare_timeout(u_abs_timeout);
917
918 ret = -EBADF;
919 filp = fget(mqdes);
920 if (unlikely(!filp))
921 goto out;
922
923 inode = filp->f_path.dentry->d_inode;
924 if (unlikely(filp->f_op != &mqueue_file_operations))
925 goto out_fput;
926 info = MQUEUE_I(inode);
927
928 if (unlikely(!(filp->f_mode & FMODE_READ)))
929 goto out_fput;
930
931 /* checks if buffer is big enough */
932 if (unlikely(msg_len < info->attr.mq_msgsize)) {
933 ret = -EMSGSIZE;
934 goto out_fput;
935 }
936
937 spin_lock(&info->lock);
938 if (info->attr.mq_curmsgs == 0) {
939 if (filp->f_flags & O_NONBLOCK) {
940 spin_unlock(&info->lock);
941 ret = -EAGAIN;
942 msg_ptr = NULL;
943 } else if (unlikely(timeout < 0)) {
944 spin_unlock(&info->lock);
945 ret = timeout;
946 msg_ptr = NULL;
947 } else {
948 wait.task = current;
949 wait.state = STATE_NONE;
950 ret = wq_sleep(info, RECV, timeout, &wait);
951 msg_ptr = wait.msg;
952 }
953 } else {
954 msg_ptr = msg_get(info);
955
956 inode->i_atime = inode->i_mtime = inode->i_ctime =
957 CURRENT_TIME;
958
959 /* There is now free space in queue. */
960 pipelined_receive(info);
961 spin_unlock(&info->lock);
962 ret = 0;
963 }
964 if (ret == 0) {
965 ret = msg_ptr->m_ts;
966
967 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
968 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
969 ret = -EFAULT;
970 }
971 free_msg(msg_ptr);
972 }
973out_fput:
974 fput(filp);
975out:
976 return ret;
977}
978
979/*
980 * Notes: the case when user wants us to deregister (with NULL as pointer)
981 * and he isn't currently owner of notification, will be silently discarded.
982 * It isn't explicitly defined in the POSIX.
983 */
984asmlinkage long sys_mq_notify(mqd_t mqdes,
985 const struct sigevent __user *u_notification)
986{
987 int ret;
988 struct file *filp;
989 struct sock *sock;
990 struct inode *inode;
991 struct sigevent notification;
992 struct mqueue_inode_info *info;
993 struct sk_buff *nc;
994
995 ret = audit_mq_notify(mqdes, u_notification);
996 if (ret != 0)
997 return ret;
998
999 nc = NULL;
1000 sock = NULL;
1001 if (u_notification != NULL) {
1002 if (copy_from_user(&notification, u_notification,
1003 sizeof(struct sigevent)))
1004 return -EFAULT;
1005
1006 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1007 notification.sigev_notify != SIGEV_SIGNAL &&
1008 notification.sigev_notify != SIGEV_THREAD))
1009 return -EINVAL;
1010 if (notification.sigev_notify == SIGEV_SIGNAL &&
1011 !valid_signal(notification.sigev_signo)) {
1012 return -EINVAL;
1013 }
1014 if (notification.sigev_notify == SIGEV_THREAD) {
1015 /* create the notify skb */
1016 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1017 ret = -ENOMEM;
1018 if (!nc)
1019 goto out;
1020 ret = -EFAULT;
1021 if (copy_from_user(nc->data,
1022 notification.sigev_value.sival_ptr,
1023 NOTIFY_COOKIE_LEN)) {
1024 goto out;
1025 }
1026
1027 /* TODO: add a header? */
1028 skb_put(nc, NOTIFY_COOKIE_LEN);
1029 /* and attach it to the socket */
1030retry:
1031 filp = fget(notification.sigev_signo);
1032 ret = -EBADF;
1033 if (!filp)
1034 goto out;
1035 sock = netlink_getsockbyfilp(filp);
1036 fput(filp);
1037 if (IS_ERR(sock)) {
1038 ret = PTR_ERR(sock);
1039 sock = NULL;
1040 goto out;
1041 }
1042
1043 ret = netlink_attachskb(sock, nc, 0,
1044 MAX_SCHEDULE_TIMEOUT, NULL);
1045 if (ret == 1)
1046 goto retry;
1047 if (ret) {
1048 sock = NULL;
1049 nc = NULL;
1050 goto out;
1051 }
1052 }
1053 }
1054
1055 ret = -EBADF;
1056 filp = fget(mqdes);
1057 if (!filp)
1058 goto out;
1059
1060 inode = filp->f_path.dentry->d_inode;
1061 if (unlikely(filp->f_op != &mqueue_file_operations))
1062 goto out_fput;
1063 info = MQUEUE_I(inode);
1064
1065 ret = 0;
1066 spin_lock(&info->lock);
1067 if (u_notification == NULL) {
1068 if (info->notify_owner == task_tgid(current)) {
1069 remove_notification(info);
1070 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1071 }
1072 } else if (info->notify_owner != NULL) {
1073 ret = -EBUSY;
1074 } else {
1075 switch (notification.sigev_notify) {
1076 case SIGEV_NONE:
1077 info->notify.sigev_notify = SIGEV_NONE;
1078 break;
1079 case SIGEV_THREAD:
1080 info->notify_sock = sock;
1081 info->notify_cookie = nc;
1082 sock = NULL;
1083 nc = NULL;
1084 info->notify.sigev_notify = SIGEV_THREAD;
1085 break;
1086 case SIGEV_SIGNAL:
1087 info->notify.sigev_signo = notification.sigev_signo;
1088 info->notify.sigev_value = notification.sigev_value;
1089 info->notify.sigev_notify = SIGEV_SIGNAL;
1090 break;
1091 }
1092
1093 info->notify_owner = get_pid(task_tgid(current));
1094 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1095 }
1096 spin_unlock(&info->lock);
1097out_fput:
1098 fput(filp);
1099out:
1100 if (sock) {
1101 netlink_detachskb(sock, nc);
1102 } else if (nc) {
1103 dev_kfree_skb(nc);
1104 }
1105 return ret;
1106}
1107
1108asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1109 const struct mq_attr __user *u_mqstat,
1110 struct mq_attr __user *u_omqstat)
1111{
1112 int ret;
1113 struct mq_attr mqstat, omqstat;
1114 struct file *filp;
1115 struct inode *inode;
1116 struct mqueue_inode_info *info;
1117
1118 if (u_mqstat != NULL) {
1119 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1120 return -EFAULT;
1121 if (mqstat.mq_flags & (~O_NONBLOCK))
1122 return -EINVAL;
1123 }
1124
1125 ret = -EBADF;
1126 filp = fget(mqdes);
1127 if (!filp)
1128 goto out;
1129
1130 inode = filp->f_path.dentry->d_inode;
1131 if (unlikely(filp->f_op != &mqueue_file_operations))
1132 goto out_fput;
1133 info = MQUEUE_I(inode);
1134
1135 spin_lock(&info->lock);
1136
1137 omqstat = info->attr;
1138 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1139 if (u_mqstat) {
1140 ret = audit_mq_getsetattr(mqdes, &mqstat);
1141 if (ret != 0)
1142 goto out;
1143 if (mqstat.mq_flags & O_NONBLOCK)
1144 filp->f_flags |= O_NONBLOCK;
1145 else
1146 filp->f_flags &= ~O_NONBLOCK;
1147
1148 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1149 }
1150
1151 spin_unlock(&info->lock);
1152
1153 ret = 0;
1154 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1155 sizeof(struct mq_attr)))
1156 ret = -EFAULT;
1157
1158out_fput:
1159 fput(filp);
1160out:
1161 return ret;
1162}
1163
1164static const struct inode_operations mqueue_dir_inode_operations = {
1165 .lookup = simple_lookup,
1166 .create = mqueue_create,
1167 .unlink = mqueue_unlink,
1168};
1169
1170static const struct file_operations mqueue_file_operations = {
1171 .flush = mqueue_flush_file,
1172 .poll = mqueue_poll_file,
1173 .read = mqueue_read_file,
1174};
1175
1176static struct super_operations mqueue_super_ops = {
1177 .alloc_inode = mqueue_alloc_inode,
1178 .destroy_inode = mqueue_destroy_inode,
1179 .statfs = simple_statfs,
1180 .delete_inode = mqueue_delete_inode,
1181 .drop_inode = generic_delete_inode,
1182};
1183
1184static struct file_system_type mqueue_fs_type = {
1185 .name = "mqueue",
1186 .get_sb = mqueue_get_sb,
1187 .kill_sb = kill_litter_super,
1188};
1189
1190static int msg_max_limit_min = DFLT_MSGMAX;
1191static int msg_max_limit_max = HARD_MSGMAX;
1192
1193static int msg_maxsize_limit_min = DFLT_MSGSIZEMAX;
1194static int msg_maxsize_limit_max = INT_MAX;
1195
1196static ctl_table mq_sysctls[] = {
1197 {
1198 .ctl_name = CTL_QUEUESMAX,
1199 .procname = "queues_max",
1200 .data = &queues_max,
1201 .maxlen = sizeof(int),
1202 .mode = 0644,
1203 .proc_handler = &proc_dointvec,
1204 },
1205 {
1206 .ctl_name = CTL_MSGMAX,
1207 .procname = "msg_max",
1208 .data = &msg_max,
1209 .maxlen = sizeof(int),
1210 .mode = 0644,
1211 .proc_handler = &proc_dointvec_minmax,
1212 .extra1 = &msg_max_limit_min,
1213 .extra2 = &msg_max_limit_max,
1214 },
1215 {
1216 .ctl_name = CTL_MSGSIZEMAX,
1217 .procname = "msgsize_max",
1218 .data = &msgsize_max,
1219 .maxlen = sizeof(int),
1220 .mode = 0644,
1221 .proc_handler = &proc_dointvec_minmax,
1222 .extra1 = &msg_maxsize_limit_min,
1223 .extra2 = &msg_maxsize_limit_max,
1224 },
1225 { .ctl_name = 0 }
1226};
1227
1228static ctl_table mq_sysctl_dir[] = {
1229 {
1230 .ctl_name = FS_MQUEUE,
1231 .procname = "mqueue",
1232 .mode = 0555,
1233 .child = mq_sysctls,
1234 },
1235 { .ctl_name = 0 }
1236};
1237
1238static ctl_table mq_sysctl_root[] = {
1239 {
1240 .ctl_name = CTL_FS,
1241 .procname = "fs",
1242 .mode = 0555,
1243 .child = mq_sysctl_dir,
1244 },
1245 { .ctl_name = 0 }
1246};
1247
1248static int __init init_mqueue_fs(void)
1249{
1250 int error;
1251
1252 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1253 sizeof(struct mqueue_inode_info), 0,
1254 SLAB_HWCACHE_ALIGN, init_once, NULL);
1255 if (mqueue_inode_cachep == NULL)
1256 return -ENOMEM;
1257
1258 /* ignore failues - they are not fatal */
1259 mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1260
1261 error = register_filesystem(&mqueue_fs_type);
1262 if (error)
1263 goto out_sysctl;
1264
1265 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1266 error = PTR_ERR(mqueue_mnt);
1267 goto out_filesystem;
1268 }
1269
1270 /* internal initialization - not common for vfs */
1271 queues_count = 0;
1272 spin_lock_init(&mq_lock);
1273
1274 return 0;
1275
1276out_filesystem:
1277 unregister_filesystem(&mqueue_fs_type);
1278out_sysctl:
1279 if (mq_sysctl_table)
1280 unregister_sysctl_table(mq_sysctl_table);
1281 kmem_cache_destroy(mqueue_inode_cachep);
1282 return error;
1283}
1284
1285__initcall(init_mqueue_fs);