projects/linux·blob v2.6.28 · refs

1293 lines · 30.3 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#include <linux/nsproxy.h>
33#include <linux/pid.h>
34
35#include <net/sock.h>
36#include "util.h"
37
38#define MQUEUE_MAGIC 0x19800202
39#define DIRENT_SIZE 20
40#define FILENT_SIZE 80
41
42#define SEND 0
43#define RECV 1
44
45#define STATE_NONE 0
46#define STATE_PENDING 1
47#define STATE_READY 2
48
49/* default values */
50#define DFLT_QUEUESMAX 256 /* max number of message queues */
51#define DFLT_MSGMAX 10 /* max number of messages in each queue */
52#define HARD_MSGMAX (131072/sizeof(void*))
53#define DFLT_MSGSIZEMAX 8192 /* max message size */
54
55/*
56 * Define the ranges various user-specified maximum values can
57 * be set to.
58 */
59#define MIN_MSGMAX 1 /* min value for msg_max */
60#define MAX_MSGMAX HARD_MSGMAX /* max value for msg_max */
61#define MIN_MSGSIZEMAX 128 /* min value for msgsize_max */
62#define MAX_MSGSIZEMAX (8192*128) /* max value for msgsize_max */
63
64struct ext_wait_queue { /* queue of sleeping tasks */
65 struct task_struct *task;
66 struct list_head list;
67 struct msg_msg *msg; /* ptr of loaded message */
68 int state; /* one of STATE_* values */
69};
70
71struct mqueue_inode_info {
72 spinlock_t lock;
73 struct inode vfs_inode;
74 wait_queue_head_t wait_q;
75
76 struct msg_msg **messages;
77 struct mq_attr attr;
78
79 struct sigevent notify;
80 struct pid* notify_owner;
81 struct user_struct *user; /* user who created, for accounting */
82 struct sock *notify_sock;
83 struct sk_buff *notify_cookie;
84
85 /* for tasks waiting for free space and messages, respectively */
86 struct ext_wait_queue e_wait_q[2];
87
88 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
89};
90
91static const struct inode_operations mqueue_dir_inode_operations;
92static const struct file_operations mqueue_file_operations;
93static struct super_operations mqueue_super_ops;
94static void remove_notification(struct mqueue_inode_info *info);
95
96static spinlock_t mq_lock;
97static struct kmem_cache *mqueue_inode_cachep;
98static struct vfsmount *mqueue_mnt;
99
100static unsigned int queues_count;
101static unsigned int queues_max = DFLT_QUEUESMAX;
102static unsigned int msg_max = DFLT_MSGMAX;
103static unsigned int msgsize_max = DFLT_MSGSIZEMAX;
104
105static struct ctl_table_header * mq_sysctl_table;
106
107static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
108{
109 return container_of(inode, struct mqueue_inode_info, vfs_inode);
110}
111
112static struct inode *mqueue_get_inode(struct super_block *sb, int mode,
113 struct mq_attr *attr)
114{
115 struct inode *inode;
116
117 inode = new_inode(sb);
118 if (inode) {
119 inode->i_mode = mode;
120 inode->i_uid = current->fsuid;
121 inode->i_gid = current->fsgid;
122 inode->i_blocks = 0;
123 inode->i_mtime = inode->i_ctime = inode->i_atime =
124 CURRENT_TIME;
125
126 if (S_ISREG(mode)) {
127 struct mqueue_inode_info *info;
128 struct task_struct *p = current;
129 struct user_struct *u = p->user;
130 unsigned long mq_bytes, mq_msg_tblsz;
131
132 inode->i_fop = &mqueue_file_operations;
133 inode->i_size = FILENT_SIZE;
134 /* mqueue specific info */
135 info = MQUEUE_I(inode);
136 spin_lock_init(&info->lock);
137 init_waitqueue_head(&info->wait_q);
138 INIT_LIST_HEAD(&info->e_wait_q[0].list);
139 INIT_LIST_HEAD(&info->e_wait_q[1].list);
140 info->messages = NULL;
141 info->notify_owner = NULL;
142 info->qsize = 0;
143 info->user = NULL; /* set when all is ok */
144 memset(&info->attr, 0, sizeof(info->attr));
145 info->attr.mq_maxmsg = msg_max;
146 info->attr.mq_msgsize = msgsize_max;
147 if (attr) {
148 info->attr.mq_maxmsg = attr->mq_maxmsg;
149 info->attr.mq_msgsize = attr->mq_msgsize;
150 }
151 mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
152 mq_bytes = (mq_msg_tblsz +
153 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
154
155 spin_lock(&mq_lock);
156 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
157 u->mq_bytes + mq_bytes >
158 p->signal->rlim[RLIMIT_MSGQUEUE].rlim_cur) {
159 spin_unlock(&mq_lock);
160 goto out_inode;
161 }
162 u->mq_bytes += mq_bytes;
163 spin_unlock(&mq_lock);
164
165 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
166 if (!info->messages) {
167 spin_lock(&mq_lock);
168 u->mq_bytes -= mq_bytes;
169 spin_unlock(&mq_lock);
170 goto out_inode;
171 }
172 /* all is ok */
173 info->user = get_uid(u);
174 } else if (S_ISDIR(mode)) {
175 inc_nlink(inode);
176 /* Some things misbehave if size == 0 on a directory */
177 inode->i_size = 2 * DIRENT_SIZE;
178 inode->i_op = &mqueue_dir_inode_operations;
179 inode->i_fop = &simple_dir_operations;
180 }
181 }
182 return inode;
183out_inode:
184 make_bad_inode(inode);
185 iput(inode);
186 return NULL;
187}
188
189static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
190{
191 struct inode *inode;
192
193 sb->s_blocksize = PAGE_CACHE_SIZE;
194 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
195 sb->s_magic = MQUEUE_MAGIC;
196 sb->s_op = &mqueue_super_ops;
197
198 inode = mqueue_get_inode(sb, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
199 if (!inode)
200 return -ENOMEM;
201
202 sb->s_root = d_alloc_root(inode);
203 if (!sb->s_root) {
204 iput(inode);
205 return -ENOMEM;
206 }
207
208 return 0;
209}
210
211static int mqueue_get_sb(struct file_system_type *fs_type,
212 int flags, const char *dev_name,
213 void *data, struct vfsmount *mnt)
214{
215 return get_sb_single(fs_type, flags, data, mqueue_fill_super, mnt);
216}
217
218static void init_once(void *foo)
219{
220 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
221
222 inode_init_once(&p->vfs_inode);
223}
224
225static struct inode *mqueue_alloc_inode(struct super_block *sb)
226{
227 struct mqueue_inode_info *ei;
228
229 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
230 if (!ei)
231 return NULL;
232 return &ei->vfs_inode;
233}
234
235static void mqueue_destroy_inode(struct inode *inode)
236{
237 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
238}
239
240static void mqueue_delete_inode(struct inode *inode)
241{
242 struct mqueue_inode_info *info;
243 struct user_struct *user;
244 unsigned long mq_bytes;
245 int i;
246
247 if (S_ISDIR(inode->i_mode)) {
248 clear_inode(inode);
249 return;
250 }
251 info = MQUEUE_I(inode);
252 spin_lock(&info->lock);
253 for (i = 0; i < info->attr.mq_curmsgs; i++)
254 free_msg(info->messages[i]);
255 kfree(info->messages);
256 spin_unlock(&info->lock);
257
258 clear_inode(inode);
259
260 mq_bytes = (info->attr.mq_maxmsg * sizeof(struct msg_msg *) +
261 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
262 user = info->user;
263 if (user) {
264 spin_lock(&mq_lock);
265 user->mq_bytes -= mq_bytes;
266 queues_count--;
267 spin_unlock(&mq_lock);
268 free_uid(user);
269 }
270}
271
272static int mqueue_create(struct inode *dir, struct dentry *dentry,
273 int mode, struct nameidata *nd)
274{
275 struct inode *inode;
276 struct mq_attr *attr = dentry->d_fsdata;
277 int error;
278
279 spin_lock(&mq_lock);
280 if (queues_count >= queues_max && !capable(CAP_SYS_RESOURCE)) {
281 error = -ENOSPC;
282 goto out_lock;
283 }
284 queues_count++;
285 spin_unlock(&mq_lock);
286
287 inode = mqueue_get_inode(dir->i_sb, mode, attr);
288 if (!inode) {
289 error = -ENOMEM;
290 spin_lock(&mq_lock);
291 queues_count--;
292 goto out_lock;
293 }
294
295 dir->i_size += DIRENT_SIZE;
296 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
297
298 d_instantiate(dentry, inode);
299 dget(dentry);
300 return 0;
301out_lock:
302 spin_unlock(&mq_lock);
303 return error;
304}
305
306static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
307{
308 struct inode *inode = dentry->d_inode;
309
310 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
311 dir->i_size -= DIRENT_SIZE;
312 drop_nlink(inode);
313 dput(dentry);
314 return 0;
315}
316
317/*
318* This is routine for system read from queue file.
319* To avoid mess with doing here some sort of mq_receive we allow
320* to read only queue size & notification info (the only values
321* that are interesting from user point of view and aren't accessible
322* through std routines)
323*/
324static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
325 size_t count, loff_t *off)
326{
327 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
328 char buffer[FILENT_SIZE];
329 ssize_t ret;
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_vnr(info->notify_owner));
340 spin_unlock(&info->lock);
341 buffer[sizeof(buffer)-1] = '\0';
342
343 ret = simple_read_from_buffer(u_data, count, off, buffer,
344 strlen(buffer));
345 if (ret <= 0)
346 return ret;
347
348 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
349 return ret;
350}
351
352static int mqueue_flush_file(struct file *filp, fl_owner_t id)
353{
354 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
355
356 spin_lock(&info->lock);
357 if (task_tgid(current) == info->notify_owner)
358 remove_notification(info);
359
360 spin_unlock(&info->lock);
361 return 0;
362}
363
364static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
365{
366 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
367 int retval = 0;
368
369 poll_wait(filp, &info->wait_q, poll_tab);
370
371 spin_lock(&info->lock);
372 if (info->attr.mq_curmsgs)
373 retval = POLLIN | POLLRDNORM;
374
375 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
376 retval |= POLLOUT | POLLWRNORM;
377 spin_unlock(&info->lock);
378
379 return retval;
380}
381
382/* Adds current to info->e_wait_q[sr] before element with smaller prio */
383static void wq_add(struct mqueue_inode_info *info, int sr,
384 struct ext_wait_queue *ewp)
385{
386 struct ext_wait_queue *walk;
387
388 ewp->task = current;
389
390 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
391 if (walk->task->static_prio <= current->static_prio) {
392 list_add_tail(&ewp->list, &walk->list);
393 return;
394 }
395 }
396 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
397}
398
399/*
400 * Puts current task to sleep. Caller must hold queue lock. After return
401 * lock isn't held.
402 * sr: SEND or RECV
403 */
404static int wq_sleep(struct mqueue_inode_info *info, int sr,
405 long timeout, struct ext_wait_queue *ewp)
406{
407 int retval;
408 signed long time;
409
410 wq_add(info, sr, ewp);
411
412 for (;;) {
413 set_current_state(TASK_INTERRUPTIBLE);
414
415 spin_unlock(&info->lock);
416 time = schedule_timeout(timeout);
417
418 while (ewp->state == STATE_PENDING)
419 cpu_relax();
420
421 if (ewp->state == STATE_READY) {
422 retval = 0;
423 goto out;
424 }
425 spin_lock(&info->lock);
426 if (ewp->state == STATE_READY) {
427 retval = 0;
428 goto out_unlock;
429 }
430 if (signal_pending(current)) {
431 retval = -ERESTARTSYS;
432 break;
433 }
434 if (time == 0) {
435 retval = -ETIMEDOUT;
436 break;
437 }
438 }
439 list_del(&ewp->list);
440out_unlock:
441 spin_unlock(&info->lock);
442out:
443 return retval;
444}
445
446/*
447 * Returns waiting task that should be serviced first or NULL if none exists
448 */
449static struct ext_wait_queue *wq_get_first_waiter(
450 struct mqueue_inode_info *info, int sr)
451{
452 struct list_head *ptr;
453
454 ptr = info->e_wait_q[sr].list.prev;
455 if (ptr == &info->e_wait_q[sr].list)
456 return NULL;
457 return list_entry(ptr, struct ext_wait_queue, list);
458}
459
460/* Auxiliary functions to manipulate messages' list */
461static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
462{
463 int k;
464
465 k = info->attr.mq_curmsgs - 1;
466 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
467 info->messages[k + 1] = info->messages[k];
468 k--;
469 }
470 info->attr.mq_curmsgs++;
471 info->qsize += ptr->m_ts;
472 info->messages[k + 1] = ptr;
473}
474
475static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
476{
477 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
478 return info->messages[info->attr.mq_curmsgs];
479}
480
481static inline void set_cookie(struct sk_buff *skb, char code)
482{
483 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
484}
485
486/*
487 * The next function is only to split too long sys_mq_timedsend
488 */
489static void __do_notify(struct mqueue_inode_info *info)
490{
491 /* notification
492 * invoked when there is registered process and there isn't process
493 * waiting synchronously for message AND state of queue changed from
494 * empty to not empty. Here we are sure that no one is waiting
495 * synchronously. */
496 if (info->notify_owner &&
497 info->attr.mq_curmsgs == 1) {
498 struct siginfo sig_i;
499 switch (info->notify.sigev_notify) {
500 case SIGEV_NONE:
501 break;
502 case SIGEV_SIGNAL:
503 /* sends signal */
504
505 sig_i.si_signo = info->notify.sigev_signo;
506 sig_i.si_errno = 0;
507 sig_i.si_code = SI_MESGQ;
508 sig_i.si_value = info->notify.sigev_value;
509 sig_i.si_pid = task_tgid_vnr(current);
510 sig_i.si_uid = current->uid;
511
512 kill_pid_info(info->notify.sigev_signo,
513 &sig_i, info->notify_owner);
514 break;
515 case SIGEV_THREAD:
516 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
517 netlink_sendskb(info->notify_sock, info->notify_cookie);
518 break;
519 }
520 /* after notification unregisters process */
521 put_pid(info->notify_owner);
522 info->notify_owner = NULL;
523 }
524 wake_up(&info->wait_q);
525}
526
527static long prepare_timeout(const struct timespec __user *u_arg)
528{
529 struct timespec ts, nowts;
530 long timeout;
531
532 if (u_arg) {
533 if (unlikely(copy_from_user(&ts, u_arg,
534 sizeof(struct timespec))))
535 return -EFAULT;
536
537 if (unlikely(ts.tv_nsec < 0 || ts.tv_sec < 0
538 || ts.tv_nsec >= NSEC_PER_SEC))
539 return -EINVAL;
540 nowts = CURRENT_TIME;
541 /* first subtract as jiffies can't be too big */
542 ts.tv_sec -= nowts.tv_sec;
543 if (ts.tv_nsec < nowts.tv_nsec) {
544 ts.tv_nsec += NSEC_PER_SEC;
545 ts.tv_sec--;
546 }
547 ts.tv_nsec -= nowts.tv_nsec;
548 if (ts.tv_sec < 0)
549 return 0;
550
551 timeout = timespec_to_jiffies(&ts) + 1;
552 } else
553 return MAX_SCHEDULE_TIMEOUT;
554
555 return timeout;
556}
557
558static void remove_notification(struct mqueue_inode_info *info)
559{
560 if (info->notify_owner != NULL &&
561 info->notify.sigev_notify == SIGEV_THREAD) {
562 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
563 netlink_sendskb(info->notify_sock, info->notify_cookie);
564 }
565 put_pid(info->notify_owner);
566 info->notify_owner = NULL;
567}
568
569static int mq_attr_ok(struct mq_attr *attr)
570{
571 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
572 return 0;
573 if (capable(CAP_SYS_RESOURCE)) {
574 if (attr->mq_maxmsg > HARD_MSGMAX)
575 return 0;
576 } else {
577 if (attr->mq_maxmsg > msg_max ||
578 attr->mq_msgsize > msgsize_max)
579 return 0;
580 }
581 /* check for overflow */
582 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
583 return 0;
584 if ((unsigned long)(attr->mq_maxmsg * attr->mq_msgsize) +
585 (attr->mq_maxmsg * sizeof (struct msg_msg *)) <
586 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
587 return 0;
588 return 1;
589}
590
591/*
592 * Invoked when creating a new queue via sys_mq_open
593 */
594static struct file *do_create(struct dentry *dir, struct dentry *dentry,
595 int oflag, mode_t mode, struct mq_attr __user *u_attr)
596{
597 struct mq_attr attr;
598 struct file *result;
599 int ret;
600
601 if (u_attr) {
602 ret = -EFAULT;
603 if (copy_from_user(&attr, u_attr, sizeof(attr)))
604 goto out;
605 ret = -EINVAL;
606 if (!mq_attr_ok(&attr))
607 goto out;
608 /* store for use during create */
609 dentry->d_fsdata = &attr;
610 }
611
612 mode &= ~current->fs->umask;
613 ret = mnt_want_write(mqueue_mnt);
614 if (ret)
615 goto out;
616 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
617 dentry->d_fsdata = NULL;
618 if (ret)
619 goto out_drop_write;
620
621 result = dentry_open(dentry, mqueue_mnt, oflag);
622 /*
623 * dentry_open() took a persistent mnt_want_write(),
624 * so we can now drop this one.
625 */
626 mnt_drop_write(mqueue_mnt);
627 return result;
628
629out_drop_write:
630 mnt_drop_write(mqueue_mnt);
631out:
632 dput(dentry);
633 mntput(mqueue_mnt);
634 return ERR_PTR(ret);
635}
636
637/* Opens existing queue */
638static struct file *do_open(struct dentry *dentry, int oflag)
639{
640static int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
641 MAY_READ | MAY_WRITE };
642
643 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
644 dput(dentry);
645 mntput(mqueue_mnt);
646 return ERR_PTR(-EINVAL);
647 }
648
649 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
650 dput(dentry);
651 mntput(mqueue_mnt);
652 return ERR_PTR(-EACCES);
653 }
654
655 return dentry_open(dentry, mqueue_mnt, oflag);
656}
657
658asmlinkage long sys_mq_open(const char __user *u_name, int oflag, mode_t mode,
659 struct mq_attr __user *u_attr)
660{
661 struct dentry *dentry;
662 struct file *filp;
663 char *name;
664 int fd, error;
665
666 error = audit_mq_open(oflag, mode, u_attr);
667 if (error != 0)
668 return error;
669
670 if (IS_ERR(name = getname(u_name)))
671 return PTR_ERR(name);
672
673 fd = get_unused_fd_flags(O_CLOEXEC);
674 if (fd < 0)
675 goto out_putname;
676
677 mutex_lock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
678 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
679 if (IS_ERR(dentry)) {
680 error = PTR_ERR(dentry);
681 goto out_err;
682 }
683 mntget(mqueue_mnt);
684
685 if (oflag & O_CREAT) {
686 if (dentry->d_inode) { /* entry already exists */
687 audit_inode(name, dentry);
688 error = -EEXIST;
689 if (oflag & O_EXCL)
690 goto out;
691 filp = do_open(dentry, oflag);
692 } else {
693 filp = do_create(mqueue_mnt->mnt_root, dentry,
694 oflag, mode, u_attr);
695 }
696 } else {
697 error = -ENOENT;
698 if (!dentry->d_inode)
699 goto out;
700 audit_inode(name, dentry);
701 filp = do_open(dentry, oflag);
702 }
703
704 if (IS_ERR(filp)) {
705 error = PTR_ERR(filp);
706 goto out_putfd;
707 }
708
709 fd_install(fd, filp);
710 goto out_upsem;
711
712out:
713 dput(dentry);
714 mntput(mqueue_mnt);
715out_putfd:
716 put_unused_fd(fd);
717out_err:
718 fd = error;
719out_upsem:
720 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
721out_putname:
722 putname(name);
723 return fd;
724}
725
726asmlinkage long sys_mq_unlink(const char __user *u_name)
727{
728 int err;
729 char *name;
730 struct dentry *dentry;
731 struct inode *inode = NULL;
732
733 name = getname(u_name);
734 if (IS_ERR(name))
735 return PTR_ERR(name);
736
737 mutex_lock_nested(&mqueue_mnt->mnt_root->d_inode->i_mutex,
738 I_MUTEX_PARENT);
739 dentry = lookup_one_len(name, mqueue_mnt->mnt_root, strlen(name));
740 if (IS_ERR(dentry)) {
741 err = PTR_ERR(dentry);
742 goto out_unlock;
743 }
744
745 if (!dentry->d_inode) {
746 err = -ENOENT;
747 goto out_err;
748 }
749
750 inode = dentry->d_inode;
751 if (inode)
752 atomic_inc(&inode->i_count);
753 err = mnt_want_write(mqueue_mnt);
754 if (err)
755 goto out_err;
756 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
757 mnt_drop_write(mqueue_mnt);
758out_err:
759 dput(dentry);
760
761out_unlock:
762 mutex_unlock(&mqueue_mnt->mnt_root->d_inode->i_mutex);
763 putname(name);
764 if (inode)
765 iput(inode);
766
767 return err;
768}
769
770/* Pipelined send and receive functions.
771 *
772 * If a receiver finds no waiting message, then it registers itself in the
773 * list of waiting receivers. A sender checks that list before adding the new
774 * message into the message array. If there is a waiting receiver, then it
775 * bypasses the message array and directly hands the message over to the
776 * receiver.
777 * The receiver accepts the message and returns without grabbing the queue
778 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
779 * are necessary. The same algorithm is used for sysv semaphores, see
780 * ipc/sem.c for more details.
781 *
782 * The same algorithm is used for senders.
783 */
784
785/* pipelined_send() - send a message directly to the task waiting in
786 * sys_mq_timedreceive() (without inserting message into a queue).
787 */
788static inline void pipelined_send(struct mqueue_inode_info *info,
789 struct msg_msg *message,
790 struct ext_wait_queue *receiver)
791{
792 receiver->msg = message;
793 list_del(&receiver->list);
794 receiver->state = STATE_PENDING;
795 wake_up_process(receiver->task);
796 smp_wmb();
797 receiver->state = STATE_READY;
798}
799
800/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
801 * gets its message and put to the queue (we have one free place for sure). */
802static inline void pipelined_receive(struct mqueue_inode_info *info)
803{
804 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
805
806 if (!sender) {
807 /* for poll */
808 wake_up_interruptible(&info->wait_q);
809 return;
810 }
811 msg_insert(sender->msg, info);
812 list_del(&sender->list);
813 sender->state = STATE_PENDING;
814 wake_up_process(sender->task);
815 smp_wmb();
816 sender->state = STATE_READY;
817}
818
819asmlinkage long sys_mq_timedsend(mqd_t mqdes, const char __user *u_msg_ptr,
820 size_t msg_len, unsigned int msg_prio,
821 const struct timespec __user *u_abs_timeout)
822{
823 struct file *filp;
824 struct inode *inode;
825 struct ext_wait_queue wait;
826 struct ext_wait_queue *receiver;
827 struct msg_msg *msg_ptr;
828 struct mqueue_inode_info *info;
829 long timeout;
830 int ret;
831
832 ret = audit_mq_timedsend(mqdes, msg_len, msg_prio, u_abs_timeout);
833 if (ret != 0)
834 return ret;
835
836 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
837 return -EINVAL;
838
839 timeout = prepare_timeout(u_abs_timeout);
840
841 ret = -EBADF;
842 filp = fget(mqdes);
843 if (unlikely(!filp))
844 goto out;
845
846 inode = filp->f_path.dentry->d_inode;
847 if (unlikely(filp->f_op != &mqueue_file_operations))
848 goto out_fput;
849 info = MQUEUE_I(inode);
850 audit_inode(NULL, filp->f_path.dentry);
851
852 if (unlikely(!(filp->f_mode & FMODE_WRITE)))
853 goto out_fput;
854
855 if (unlikely(msg_len > info->attr.mq_msgsize)) {
856 ret = -EMSGSIZE;
857 goto out_fput;
858 }
859
860 /* First try to allocate memory, before doing anything with
861 * existing queues. */
862 msg_ptr = load_msg(u_msg_ptr, msg_len);
863 if (IS_ERR(msg_ptr)) {
864 ret = PTR_ERR(msg_ptr);
865 goto out_fput;
866 }
867 msg_ptr->m_ts = msg_len;
868 msg_ptr->m_type = msg_prio;
869
870 spin_lock(&info->lock);
871
872 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
873 if (filp->f_flags & O_NONBLOCK) {
874 spin_unlock(&info->lock);
875 ret = -EAGAIN;
876 } else if (unlikely(timeout < 0)) {
877 spin_unlock(&info->lock);
878 ret = timeout;
879 } else {
880 wait.task = current;
881 wait.msg = (void *) msg_ptr;
882 wait.state = STATE_NONE;
883 ret = wq_sleep(info, SEND, timeout, &wait);
884 }
885 if (ret < 0)
886 free_msg(msg_ptr);
887 } else {
888 receiver = wq_get_first_waiter(info, RECV);
889 if (receiver) {
890 pipelined_send(info, msg_ptr, receiver);
891 } else {
892 /* adds message to the queue */
893 msg_insert(msg_ptr, info);
894 __do_notify(info);
895 }
896 inode->i_atime = inode->i_mtime = inode->i_ctime =
897 CURRENT_TIME;
898 spin_unlock(&info->lock);
899 ret = 0;
900 }
901out_fput:
902 fput(filp);
903out:
904 return ret;
905}
906
907asmlinkage ssize_t sys_mq_timedreceive(mqd_t mqdes, char __user *u_msg_ptr,
908 size_t msg_len, unsigned int __user *u_msg_prio,
909 const struct timespec __user *u_abs_timeout)
910{
911 long timeout;
912 ssize_t ret;
913 struct msg_msg *msg_ptr;
914 struct file *filp;
915 struct inode *inode;
916 struct mqueue_inode_info *info;
917 struct ext_wait_queue wait;
918
919 ret = audit_mq_timedreceive(mqdes, msg_len, u_msg_prio, u_abs_timeout);
920 if (ret != 0)
921 return ret;
922
923 timeout = prepare_timeout(u_abs_timeout);
924
925 ret = -EBADF;
926 filp = fget(mqdes);
927 if (unlikely(!filp))
928 goto out;
929
930 inode = filp->f_path.dentry->d_inode;
931 if (unlikely(filp->f_op != &mqueue_file_operations))
932 goto out_fput;
933 info = MQUEUE_I(inode);
934 audit_inode(NULL, filp->f_path.dentry);
935
936 if (unlikely(!(filp->f_mode & FMODE_READ)))
937 goto out_fput;
938
939 /* checks if buffer is big enough */
940 if (unlikely(msg_len < info->attr.mq_msgsize)) {
941 ret = -EMSGSIZE;
942 goto out_fput;
943 }
944
945 spin_lock(&info->lock);
946 if (info->attr.mq_curmsgs == 0) {
947 if (filp->f_flags & O_NONBLOCK) {
948 spin_unlock(&info->lock);
949 ret = -EAGAIN;
950 msg_ptr = NULL;
951 } else if (unlikely(timeout < 0)) {
952 spin_unlock(&info->lock);
953 ret = timeout;
954 msg_ptr = NULL;
955 } else {
956 wait.task = current;
957 wait.state = STATE_NONE;
958 ret = wq_sleep(info, RECV, timeout, &wait);
959 msg_ptr = wait.msg;
960 }
961 } else {
962 msg_ptr = msg_get(info);
963
964 inode->i_atime = inode->i_mtime = inode->i_ctime =
965 CURRENT_TIME;
966
967 /* There is now free space in queue. */
968 pipelined_receive(info);
969 spin_unlock(&info->lock);
970 ret = 0;
971 }
972 if (ret == 0) {
973 ret = msg_ptr->m_ts;
974
975 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
976 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
977 ret = -EFAULT;
978 }
979 free_msg(msg_ptr);
980 }
981out_fput:
982 fput(filp);
983out:
984 return ret;
985}
986
987/*
988 * Notes: the case when user wants us to deregister (with NULL as pointer)
989 * and he isn't currently owner of notification, will be silently discarded.
990 * It isn't explicitly defined in the POSIX.
991 */
992asmlinkage long sys_mq_notify(mqd_t mqdes,
993 const struct sigevent __user *u_notification)
994{
995 int ret;
996 struct file *filp;
997 struct sock *sock;
998 struct inode *inode;
999 struct sigevent notification;
1000 struct mqueue_inode_info *info;
1001 struct sk_buff *nc;
1002
1003 ret = audit_mq_notify(mqdes, u_notification);
1004 if (ret != 0)
1005 return ret;
1006
1007 nc = NULL;
1008 sock = NULL;
1009 if (u_notification != NULL) {
1010 if (copy_from_user(&notification, u_notification,
1011 sizeof(struct sigevent)))
1012 return -EFAULT;
1013
1014 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1015 notification.sigev_notify != SIGEV_SIGNAL &&
1016 notification.sigev_notify != SIGEV_THREAD))
1017 return -EINVAL;
1018 if (notification.sigev_notify == SIGEV_SIGNAL &&
1019 !valid_signal(notification.sigev_signo)) {
1020 return -EINVAL;
1021 }
1022 if (notification.sigev_notify == SIGEV_THREAD) {
1023 long timeo;
1024
1025 /* create the notify skb */
1026 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1027 ret = -ENOMEM;
1028 if (!nc)
1029 goto out;
1030 ret = -EFAULT;
1031 if (copy_from_user(nc->data,
1032 notification.sigev_value.sival_ptr,
1033 NOTIFY_COOKIE_LEN)) {
1034 goto out;
1035 }
1036
1037 /* TODO: add a header? */
1038 skb_put(nc, NOTIFY_COOKIE_LEN);
1039 /* and attach it to the socket */
1040retry:
1041 filp = fget(notification.sigev_signo);
1042 ret = -EBADF;
1043 if (!filp)
1044 goto out;
1045 sock = netlink_getsockbyfilp(filp);
1046 fput(filp);
1047 if (IS_ERR(sock)) {
1048 ret = PTR_ERR(sock);
1049 sock = NULL;
1050 goto out;
1051 }
1052
1053 timeo = MAX_SCHEDULE_TIMEOUT;
1054 ret = netlink_attachskb(sock, nc, &timeo, NULL);
1055 if (ret == 1)
1056 goto retry;
1057 if (ret) {
1058 sock = NULL;
1059 nc = NULL;
1060 goto out;
1061 }
1062 }
1063 }
1064
1065 ret = -EBADF;
1066 filp = fget(mqdes);
1067 if (!filp)
1068 goto out;
1069
1070 inode = filp->f_path.dentry->d_inode;
1071 if (unlikely(filp->f_op != &mqueue_file_operations))
1072 goto out_fput;
1073 info = MQUEUE_I(inode);
1074
1075 ret = 0;
1076 spin_lock(&info->lock);
1077 if (u_notification == NULL) {
1078 if (info->notify_owner == task_tgid(current)) {
1079 remove_notification(info);
1080 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1081 }
1082 } else if (info->notify_owner != NULL) {
1083 ret = -EBUSY;
1084 } else {
1085 switch (notification.sigev_notify) {
1086 case SIGEV_NONE:
1087 info->notify.sigev_notify = SIGEV_NONE;
1088 break;
1089 case SIGEV_THREAD:
1090 info->notify_sock = sock;
1091 info->notify_cookie = nc;
1092 sock = NULL;
1093 nc = NULL;
1094 info->notify.sigev_notify = SIGEV_THREAD;
1095 break;
1096 case SIGEV_SIGNAL:
1097 info->notify.sigev_signo = notification.sigev_signo;
1098 info->notify.sigev_value = notification.sigev_value;
1099 info->notify.sigev_notify = SIGEV_SIGNAL;
1100 break;
1101 }
1102
1103 info->notify_owner = get_pid(task_tgid(current));
1104 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1105 }
1106 spin_unlock(&info->lock);
1107out_fput:
1108 fput(filp);
1109out:
1110 if (sock) {
1111 netlink_detachskb(sock, nc);
1112 } else if (nc) {
1113 dev_kfree_skb(nc);
1114 }
1115 return ret;
1116}
1117
1118asmlinkage long sys_mq_getsetattr(mqd_t mqdes,
1119 const struct mq_attr __user *u_mqstat,
1120 struct mq_attr __user *u_omqstat)
1121{
1122 int ret;
1123 struct mq_attr mqstat, omqstat;
1124 struct file *filp;
1125 struct inode *inode;
1126 struct mqueue_inode_info *info;
1127
1128 if (u_mqstat != NULL) {
1129 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1130 return -EFAULT;
1131 if (mqstat.mq_flags & (~O_NONBLOCK))
1132 return -EINVAL;
1133 }
1134
1135 ret = -EBADF;
1136 filp = fget(mqdes);
1137 if (!filp)
1138 goto out;
1139
1140 inode = filp->f_path.dentry->d_inode;
1141 if (unlikely(filp->f_op != &mqueue_file_operations))
1142 goto out_fput;
1143 info = MQUEUE_I(inode);
1144
1145 spin_lock(&info->lock);
1146
1147 omqstat = info->attr;
1148 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1149 if (u_mqstat) {
1150 ret = audit_mq_getsetattr(mqdes, &mqstat);
1151 if (ret != 0) {
1152 spin_unlock(&info->lock);
1153 goto out_fput;
1154 }
1155 if (mqstat.mq_flags & O_NONBLOCK)
1156 filp->f_flags |= O_NONBLOCK;
1157 else
1158 filp->f_flags &= ~O_NONBLOCK;
1159
1160 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1161 }
1162
1163 spin_unlock(&info->lock);
1164
1165 ret = 0;
1166 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1167 sizeof(struct mq_attr)))
1168 ret = -EFAULT;
1169
1170out_fput:
1171 fput(filp);
1172out:
1173 return ret;
1174}
1175
1176static const struct inode_operations mqueue_dir_inode_operations = {
1177 .lookup = simple_lookup,
1178 .create = mqueue_create,
1179 .unlink = mqueue_unlink,
1180};
1181
1182static const struct file_operations mqueue_file_operations = {
1183 .flush = mqueue_flush_file,
1184 .poll = mqueue_poll_file,
1185 .read = mqueue_read_file,
1186};
1187
1188static struct super_operations mqueue_super_ops = {
1189 .alloc_inode = mqueue_alloc_inode,
1190 .destroy_inode = mqueue_destroy_inode,
1191 .statfs = simple_statfs,
1192 .delete_inode = mqueue_delete_inode,
1193 .drop_inode = generic_delete_inode,
1194};
1195
1196static struct file_system_type mqueue_fs_type = {
1197 .name = "mqueue",
1198 .get_sb = mqueue_get_sb,
1199 .kill_sb = kill_litter_super,
1200};
1201
1202static int msg_max_limit_min = MIN_MSGMAX;
1203static int msg_max_limit_max = MAX_MSGMAX;
1204
1205static int msg_maxsize_limit_min = MIN_MSGSIZEMAX;
1206static int msg_maxsize_limit_max = MAX_MSGSIZEMAX;
1207
1208static ctl_table mq_sysctls[] = {
1209 {
1210 .procname = "queues_max",
1211 .data = &queues_max,
1212 .maxlen = sizeof(int),
1213 .mode = 0644,
1214 .proc_handler = &proc_dointvec,
1215 },
1216 {
1217 .procname = "msg_max",
1218 .data = &msg_max,
1219 .maxlen = sizeof(int),
1220 .mode = 0644,
1221 .proc_handler = &proc_dointvec_minmax,
1222 .extra1 = &msg_max_limit_min,
1223 .extra2 = &msg_max_limit_max,
1224 },
1225 {
1226 .procname = "msgsize_max",
1227 .data = &msgsize_max,
1228 .maxlen = sizeof(int),
1229 .mode = 0644,
1230 .proc_handler = &proc_dointvec_minmax,
1231 .extra1 = &msg_maxsize_limit_min,
1232 .extra2 = &msg_maxsize_limit_max,
1233 },
1234 { .ctl_name = 0 }
1235};
1236
1237static ctl_table mq_sysctl_dir[] = {
1238 {
1239 .procname = "mqueue",
1240 .mode = 0555,
1241 .child = mq_sysctls,
1242 },
1243 { .ctl_name = 0 }
1244};
1245
1246static ctl_table mq_sysctl_root[] = {
1247 {
1248 .ctl_name = CTL_FS,
1249 .procname = "fs",
1250 .mode = 0555,
1251 .child = mq_sysctl_dir,
1252 },
1253 { .ctl_name = 0 }
1254};
1255
1256static int __init init_mqueue_fs(void)
1257{
1258 int error;
1259
1260 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1261 sizeof(struct mqueue_inode_info), 0,
1262 SLAB_HWCACHE_ALIGN, init_once);
1263 if (mqueue_inode_cachep == NULL)
1264 return -ENOMEM;
1265
1266 /* ignore failues - they are not fatal */
1267 mq_sysctl_table = register_sysctl_table(mq_sysctl_root);
1268
1269 error = register_filesystem(&mqueue_fs_type);
1270 if (error)
1271 goto out_sysctl;
1272
1273 if (IS_ERR(mqueue_mnt = kern_mount(&mqueue_fs_type))) {
1274 error = PTR_ERR(mqueue_mnt);
1275 goto out_filesystem;
1276 }
1277
1278 /* internal initialization - not common for vfs */
1279 queues_count = 0;
1280 spin_lock_init(&mq_lock);
1281
1282 return 0;
1283
1284out_filesystem:
1285 unregister_filesystem(&mqueue_fs_type);
1286out_sysctl:
1287 if (mq_sysctl_table)
1288 unregister_sysctl_table(mq_sysctl_table);
1289 kmem_cache_destroy(mqueue_inode_cachep);
1290 return error;
1291}
1292
1293__initcall(init_mqueue_fs);