projects/linux·blob v3.3 · refs

1312 lines · 30.6 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#include <linux/ipc_namespace.h>
35#include <linux/user_namespace.h>
36#include <linux/slab.h>
37
38#include <net/sock.h>
39#include "util.h"
40
41#define MQUEUE_MAGIC 0x19800202
42#define DIRENT_SIZE 20
43#define FILENT_SIZE 80
44
45#define SEND 0
46#define RECV 1
47
48#define STATE_NONE 0
49#define STATE_PENDING 1
50#define STATE_READY 2
51
52struct ext_wait_queue { /* queue of sleeping tasks */
53 struct task_struct *task;
54 struct list_head list;
55 struct msg_msg *msg; /* ptr of loaded message */
56 int state; /* one of STATE_* values */
57};
58
59struct mqueue_inode_info {
60 spinlock_t lock;
61 struct inode vfs_inode;
62 wait_queue_head_t wait_q;
63
64 struct msg_msg **messages;
65 struct mq_attr attr;
66
67 struct sigevent notify;
68 struct pid* notify_owner;
69 struct user_struct *user; /* user who created, for accounting */
70 struct sock *notify_sock;
71 struct sk_buff *notify_cookie;
72
73 /* for tasks waiting for free space and messages, respectively */
74 struct ext_wait_queue e_wait_q[2];
75
76 unsigned long qsize; /* size of queue in memory (sum of all msgs) */
77};
78
79static const struct inode_operations mqueue_dir_inode_operations;
80static const struct file_operations mqueue_file_operations;
81static const struct super_operations mqueue_super_ops;
82static void remove_notification(struct mqueue_inode_info *info);
83
84static struct kmem_cache *mqueue_inode_cachep;
85
86static struct ctl_table_header * mq_sysctl_table;
87
88static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
89{
90 return container_of(inode, struct mqueue_inode_info, vfs_inode);
91}
92
93/*
94 * This routine should be called with the mq_lock held.
95 */
96static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
97{
98 return get_ipc_ns(inode->i_sb->s_fs_info);
99}
100
101static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
102{
103 struct ipc_namespace *ns;
104
105 spin_lock(&mq_lock);
106 ns = __get_ns_from_inode(inode);
107 spin_unlock(&mq_lock);
108 return ns;
109}
110
111static struct inode *mqueue_get_inode(struct super_block *sb,
112 struct ipc_namespace *ipc_ns, umode_t mode,
113 struct mq_attr *attr)
114{
115 struct user_struct *u = current_user();
116 struct inode *inode;
117 int ret = -ENOMEM;
118
119 inode = new_inode(sb);
120 if (!inode)
121 goto err;
122
123 inode->i_ino = get_next_ino();
124 inode->i_mode = mode;
125 inode->i_uid = current_fsuid();
126 inode->i_gid = current_fsgid();
127 inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
128
129 if (S_ISREG(mode)) {
130 struct mqueue_inode_info *info;
131 unsigned long mq_bytes, mq_msg_tblsz;
132
133 inode->i_fop = &mqueue_file_operations;
134 inode->i_size = FILENT_SIZE;
135 /* mqueue specific info */
136 info = MQUEUE_I(inode);
137 spin_lock_init(&info->lock);
138 init_waitqueue_head(&info->wait_q);
139 INIT_LIST_HEAD(&info->e_wait_q[0].list);
140 INIT_LIST_HEAD(&info->e_wait_q[1].list);
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 = ipc_ns->mq_msg_max;
146 info->attr.mq_msgsize = ipc_ns->mq_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 info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
153 if (!info->messages)
154 goto out_inode;
155
156 mq_bytes = (mq_msg_tblsz +
157 (info->attr.mq_maxmsg * info->attr.mq_msgsize));
158
159 spin_lock(&mq_lock);
160 if (u->mq_bytes + mq_bytes < u->mq_bytes ||
161 u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
162 spin_unlock(&mq_lock);
163 /* mqueue_evict_inode() releases info->messages */
164 ret = -EMFILE;
165 goto out_inode;
166 }
167 u->mq_bytes += mq_bytes;
168 spin_unlock(&mq_lock);
169
170 /* all is ok */
171 info->user = get_uid(u);
172 } else if (S_ISDIR(mode)) {
173 inc_nlink(inode);
174 /* Some things misbehave if size == 0 on a directory */
175 inode->i_size = 2 * DIRENT_SIZE;
176 inode->i_op = &mqueue_dir_inode_operations;
177 inode->i_fop = &simple_dir_operations;
178 }
179
180 return inode;
181out_inode:
182 iput(inode);
183err:
184 return ERR_PTR(ret);
185}
186
187static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
188{
189 struct inode *inode;
190 struct ipc_namespace *ns = data;
191 int error;
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, ns, S_IFDIR | S_ISVTX | S_IRWXUGO,
199 NULL);
200 if (IS_ERR(inode)) {
201 error = PTR_ERR(inode);
202 goto out;
203 }
204
205 sb->s_root = d_alloc_root(inode);
206 if (!sb->s_root) {
207 iput(inode);
208 error = -ENOMEM;
209 goto out;
210 }
211 error = 0;
212
213out:
214 return error;
215}
216
217static struct dentry *mqueue_mount(struct file_system_type *fs_type,
218 int flags, const char *dev_name,
219 void *data)
220{
221 if (!(flags & MS_KERNMOUNT))
222 data = current->nsproxy->ipc_ns;
223 return mount_ns(fs_type, flags, data, mqueue_fill_super);
224}
225
226static void init_once(void *foo)
227{
228 struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
229
230 inode_init_once(&p->vfs_inode);
231}
232
233static struct inode *mqueue_alloc_inode(struct super_block *sb)
234{
235 struct mqueue_inode_info *ei;
236
237 ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
238 if (!ei)
239 return NULL;
240 return &ei->vfs_inode;
241}
242
243static void mqueue_i_callback(struct rcu_head *head)
244{
245 struct inode *inode = container_of(head, struct inode, i_rcu);
246 kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
247}
248
249static void mqueue_destroy_inode(struct inode *inode)
250{
251 call_rcu(&inode->i_rcu, mqueue_i_callback);
252}
253
254static void mqueue_evict_inode(struct inode *inode)
255{
256 struct mqueue_inode_info *info;
257 struct user_struct *user;
258 unsigned long mq_bytes;
259 int i;
260 struct ipc_namespace *ipc_ns;
261
262 end_writeback(inode);
263
264 if (S_ISDIR(inode->i_mode))
265 return;
266
267 ipc_ns = get_ns_from_inode(inode);
268 info = MQUEUE_I(inode);
269 spin_lock(&info->lock);
270 for (i = 0; i < info->attr.mq_curmsgs; i++)
271 free_msg(info->messages[i]);
272 kfree(info->messages);
273 spin_unlock(&info->lock);
274
275 /* Total amount of bytes accounted for the mqueue */
276 mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
277 + info->attr.mq_msgsize);
278 user = info->user;
279 if (user) {
280 spin_lock(&mq_lock);
281 user->mq_bytes -= mq_bytes;
282 /*
283 * get_ns_from_inode() ensures that the
284 * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
285 * to which we now hold a reference, or it is NULL.
286 * We can't put it here under mq_lock, though.
287 */
288 if (ipc_ns)
289 ipc_ns->mq_queues_count--;
290 spin_unlock(&mq_lock);
291 free_uid(user);
292 }
293 if (ipc_ns)
294 put_ipc_ns(ipc_ns);
295}
296
297static int mqueue_create(struct inode *dir, struct dentry *dentry,
298 umode_t mode, struct nameidata *nd)
299{
300 struct inode *inode;
301 struct mq_attr *attr = dentry->d_fsdata;
302 int error;
303 struct ipc_namespace *ipc_ns;
304
305 spin_lock(&mq_lock);
306 ipc_ns = __get_ns_from_inode(dir);
307 if (!ipc_ns) {
308 error = -EACCES;
309 goto out_unlock;
310 }
311 if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
312 !capable(CAP_SYS_RESOURCE)) {
313 error = -ENOSPC;
314 goto out_unlock;
315 }
316 ipc_ns->mq_queues_count++;
317 spin_unlock(&mq_lock);
318
319 inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
320 if (IS_ERR(inode)) {
321 error = PTR_ERR(inode);
322 spin_lock(&mq_lock);
323 ipc_ns->mq_queues_count--;
324 goto out_unlock;
325 }
326
327 put_ipc_ns(ipc_ns);
328 dir->i_size += DIRENT_SIZE;
329 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
330
331 d_instantiate(dentry, inode);
332 dget(dentry);
333 return 0;
334out_unlock:
335 spin_unlock(&mq_lock);
336 if (ipc_ns)
337 put_ipc_ns(ipc_ns);
338 return error;
339}
340
341static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
342{
343 struct inode *inode = dentry->d_inode;
344
345 dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
346 dir->i_size -= DIRENT_SIZE;
347 drop_nlink(inode);
348 dput(dentry);
349 return 0;
350}
351
352/*
353* This is routine for system read from queue file.
354* To avoid mess with doing here some sort of mq_receive we allow
355* to read only queue size & notification info (the only values
356* that are interesting from user point of view and aren't accessible
357* through std routines)
358*/
359static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
360 size_t count, loff_t *off)
361{
362 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
363 char buffer[FILENT_SIZE];
364 ssize_t ret;
365
366 spin_lock(&info->lock);
367 snprintf(buffer, sizeof(buffer),
368 "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
369 info->qsize,
370 info->notify_owner ? info->notify.sigev_notify : 0,
371 (info->notify_owner &&
372 info->notify.sigev_notify == SIGEV_SIGNAL) ?
373 info->notify.sigev_signo : 0,
374 pid_vnr(info->notify_owner));
375 spin_unlock(&info->lock);
376 buffer[sizeof(buffer)-1] = '\0';
377
378 ret = simple_read_from_buffer(u_data, count, off, buffer,
379 strlen(buffer));
380 if (ret <= 0)
381 return ret;
382
383 filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
384 return ret;
385}
386
387static int mqueue_flush_file(struct file *filp, fl_owner_t id)
388{
389 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
390
391 spin_lock(&info->lock);
392 if (task_tgid(current) == info->notify_owner)
393 remove_notification(info);
394
395 spin_unlock(&info->lock);
396 return 0;
397}
398
399static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
400{
401 struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
402 int retval = 0;
403
404 poll_wait(filp, &info->wait_q, poll_tab);
405
406 spin_lock(&info->lock);
407 if (info->attr.mq_curmsgs)
408 retval = POLLIN | POLLRDNORM;
409
410 if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
411 retval |= POLLOUT | POLLWRNORM;
412 spin_unlock(&info->lock);
413
414 return retval;
415}
416
417/* Adds current to info->e_wait_q[sr] before element with smaller prio */
418static void wq_add(struct mqueue_inode_info *info, int sr,
419 struct ext_wait_queue *ewp)
420{
421 struct ext_wait_queue *walk;
422
423 ewp->task = current;
424
425 list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
426 if (walk->task->static_prio <= current->static_prio) {
427 list_add_tail(&ewp->list, &walk->list);
428 return;
429 }
430 }
431 list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
432}
433
434/*
435 * Puts current task to sleep. Caller must hold queue lock. After return
436 * lock isn't held.
437 * sr: SEND or RECV
438 */
439static int wq_sleep(struct mqueue_inode_info *info, int sr,
440 ktime_t *timeout, struct ext_wait_queue *ewp)
441{
442 int retval;
443 signed long time;
444
445 wq_add(info, sr, ewp);
446
447 for (;;) {
448 set_current_state(TASK_INTERRUPTIBLE);
449
450 spin_unlock(&info->lock);
451 time = schedule_hrtimeout_range_clock(timeout, 0,
452 HRTIMER_MODE_ABS, CLOCK_REALTIME);
453
454 while (ewp->state == STATE_PENDING)
455 cpu_relax();
456
457 if (ewp->state == STATE_READY) {
458 retval = 0;
459 goto out;
460 }
461 spin_lock(&info->lock);
462 if (ewp->state == STATE_READY) {
463 retval = 0;
464 goto out_unlock;
465 }
466 if (signal_pending(current)) {
467 retval = -ERESTARTSYS;
468 break;
469 }
470 if (time == 0) {
471 retval = -ETIMEDOUT;
472 break;
473 }
474 }
475 list_del(&ewp->list);
476out_unlock:
477 spin_unlock(&info->lock);
478out:
479 return retval;
480}
481
482/*
483 * Returns waiting task that should be serviced first or NULL if none exists
484 */
485static struct ext_wait_queue *wq_get_first_waiter(
486 struct mqueue_inode_info *info, int sr)
487{
488 struct list_head *ptr;
489
490 ptr = info->e_wait_q[sr].list.prev;
491 if (ptr == &info->e_wait_q[sr].list)
492 return NULL;
493 return list_entry(ptr, struct ext_wait_queue, list);
494}
495
496/* Auxiliary functions to manipulate messages' list */
497static void msg_insert(struct msg_msg *ptr, struct mqueue_inode_info *info)
498{
499 int k;
500
501 k = info->attr.mq_curmsgs - 1;
502 while (k >= 0 && info->messages[k]->m_type >= ptr->m_type) {
503 info->messages[k + 1] = info->messages[k];
504 k--;
505 }
506 info->attr.mq_curmsgs++;
507 info->qsize += ptr->m_ts;
508 info->messages[k + 1] = ptr;
509}
510
511static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
512{
513 info->qsize -= info->messages[--info->attr.mq_curmsgs]->m_ts;
514 return info->messages[info->attr.mq_curmsgs];
515}
516
517static inline void set_cookie(struct sk_buff *skb, char code)
518{
519 ((char*)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
520}
521
522/*
523 * The next function is only to split too long sys_mq_timedsend
524 */
525static void __do_notify(struct mqueue_inode_info *info)
526{
527 /* notification
528 * invoked when there is registered process and there isn't process
529 * waiting synchronously for message AND state of queue changed from
530 * empty to not empty. Here we are sure that no one is waiting
531 * synchronously. */
532 if (info->notify_owner &&
533 info->attr.mq_curmsgs == 1) {
534 struct siginfo sig_i;
535 switch (info->notify.sigev_notify) {
536 case SIGEV_NONE:
537 break;
538 case SIGEV_SIGNAL:
539 /* sends signal */
540
541 sig_i.si_signo = info->notify.sigev_signo;
542 sig_i.si_errno = 0;
543 sig_i.si_code = SI_MESGQ;
544 sig_i.si_value = info->notify.sigev_value;
545 /* map current pid/uid into info->owner's namespaces */
546 rcu_read_lock();
547 sig_i.si_pid = task_tgid_nr_ns(current,
548 ns_of_pid(info->notify_owner));
549 sig_i.si_uid = user_ns_map_uid(info->user->user_ns,
550 current_cred(), current_uid());
551 rcu_read_unlock();
552
553 kill_pid_info(info->notify.sigev_signo,
554 &sig_i, info->notify_owner);
555 break;
556 case SIGEV_THREAD:
557 set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
558 netlink_sendskb(info->notify_sock, info->notify_cookie);
559 break;
560 }
561 /* after notification unregisters process */
562 put_pid(info->notify_owner);
563 info->notify_owner = NULL;
564 }
565 wake_up(&info->wait_q);
566}
567
568static int prepare_timeout(const struct timespec __user *u_abs_timeout,
569 ktime_t *expires, struct timespec *ts)
570{
571 if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
572 return -EFAULT;
573 if (!timespec_valid(ts))
574 return -EINVAL;
575
576 *expires = timespec_to_ktime(*ts);
577 return 0;
578}
579
580static void remove_notification(struct mqueue_inode_info *info)
581{
582 if (info->notify_owner != NULL &&
583 info->notify.sigev_notify == SIGEV_THREAD) {
584 set_cookie(info->notify_cookie, NOTIFY_REMOVED);
585 netlink_sendskb(info->notify_sock, info->notify_cookie);
586 }
587 put_pid(info->notify_owner);
588 info->notify_owner = NULL;
589}
590
591static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
592{
593 if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
594 return 0;
595 if (capable(CAP_SYS_RESOURCE)) {
596 if (attr->mq_maxmsg > HARD_MSGMAX)
597 return 0;
598 } else {
599 if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
600 attr->mq_msgsize > ipc_ns->mq_msgsize_max)
601 return 0;
602 }
603 /* check for overflow */
604 if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
605 return 0;
606 if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
607 + sizeof (struct msg_msg *))) <
608 (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
609 return 0;
610 return 1;
611}
612
613/*
614 * Invoked when creating a new queue via sys_mq_open
615 */
616static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
617 struct dentry *dentry, int oflag, umode_t mode,
618 struct mq_attr *attr)
619{
620 const struct cred *cred = current_cred();
621 struct file *result;
622 int ret;
623
624 if (attr) {
625 if (!mq_attr_ok(ipc_ns, attr)) {
626 ret = -EINVAL;
627 goto out;
628 }
629 /* store for use during create */
630 dentry->d_fsdata = attr;
631 }
632
633 mode &= ~current_umask();
634 ret = mnt_want_write(ipc_ns->mq_mnt);
635 if (ret)
636 goto out;
637 ret = vfs_create(dir->d_inode, dentry, mode, NULL);
638 dentry->d_fsdata = NULL;
639 if (ret)
640 goto out_drop_write;
641
642 result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
643 /*
644 * dentry_open() took a persistent mnt_want_write(),
645 * so we can now drop this one.
646 */
647 mnt_drop_write(ipc_ns->mq_mnt);
648 return result;
649
650out_drop_write:
651 mnt_drop_write(ipc_ns->mq_mnt);
652out:
653 dput(dentry);
654 mntput(ipc_ns->mq_mnt);
655 return ERR_PTR(ret);
656}
657
658/* Opens existing queue */
659static struct file *do_open(struct ipc_namespace *ipc_ns,
660 struct dentry *dentry, int oflag)
661{
662 int ret;
663 const struct cred *cred = current_cred();
664
665 static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
666 MAY_READ | MAY_WRITE };
667
668 if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
669 ret = -EINVAL;
670 goto err;
671 }
672
673 if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
674 ret = -EACCES;
675 goto err;
676 }
677
678 return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
679
680err:
681 dput(dentry);
682 mntput(ipc_ns->mq_mnt);
683 return ERR_PTR(ret);
684}
685
686SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
687 struct mq_attr __user *, u_attr)
688{
689 struct dentry *dentry;
690 struct file *filp;
691 char *name;
692 struct mq_attr attr;
693 int fd, error;
694 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
695
696 if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
697 return -EFAULT;
698
699 audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
700
701 if (IS_ERR(name = getname(u_name)))
702 return PTR_ERR(name);
703
704 fd = get_unused_fd_flags(O_CLOEXEC);
705 if (fd < 0)
706 goto out_putname;
707
708 mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
709 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
710 if (IS_ERR(dentry)) {
711 error = PTR_ERR(dentry);
712 goto out_putfd;
713 }
714 mntget(ipc_ns->mq_mnt);
715
716 if (oflag & O_CREAT) {
717 if (dentry->d_inode) { /* entry already exists */
718 audit_inode(name, dentry);
719 if (oflag & O_EXCL) {
720 error = -EEXIST;
721 goto out;
722 }
723 filp = do_open(ipc_ns, dentry, oflag);
724 } else {
725 filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
726 dentry, oflag, mode,
727 u_attr ? &attr : NULL);
728 }
729 } else {
730 if (!dentry->d_inode) {
731 error = -ENOENT;
732 goto out;
733 }
734 audit_inode(name, dentry);
735 filp = do_open(ipc_ns, dentry, oflag);
736 }
737
738 if (IS_ERR(filp)) {
739 error = PTR_ERR(filp);
740 goto out_putfd;
741 }
742
743 fd_install(fd, filp);
744 goto out_upsem;
745
746out:
747 dput(dentry);
748 mntput(ipc_ns->mq_mnt);
749out_putfd:
750 put_unused_fd(fd);
751 fd = error;
752out_upsem:
753 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
754out_putname:
755 putname(name);
756 return fd;
757}
758
759SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
760{
761 int err;
762 char *name;
763 struct dentry *dentry;
764 struct inode *inode = NULL;
765 struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
766
767 name = getname(u_name);
768 if (IS_ERR(name))
769 return PTR_ERR(name);
770
771 mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
772 I_MUTEX_PARENT);
773 dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
774 if (IS_ERR(dentry)) {
775 err = PTR_ERR(dentry);
776 goto out_unlock;
777 }
778
779 if (!dentry->d_inode) {
780 err = -ENOENT;
781 goto out_err;
782 }
783
784 inode = dentry->d_inode;
785 if (inode)
786 ihold(inode);
787 err = mnt_want_write(ipc_ns->mq_mnt);
788 if (err)
789 goto out_err;
790 err = vfs_unlink(dentry->d_parent->d_inode, dentry);
791 mnt_drop_write(ipc_ns->mq_mnt);
792out_err:
793 dput(dentry);
794
795out_unlock:
796 mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
797 putname(name);
798 if (inode)
799 iput(inode);
800
801 return err;
802}
803
804/* Pipelined send and receive functions.
805 *
806 * If a receiver finds no waiting message, then it registers itself in the
807 * list of waiting receivers. A sender checks that list before adding the new
808 * message into the message array. If there is a waiting receiver, then it
809 * bypasses the message array and directly hands the message over to the
810 * receiver.
811 * The receiver accepts the message and returns without grabbing the queue
812 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
813 * are necessary. The same algorithm is used for sysv semaphores, see
814 * ipc/sem.c for more details.
815 *
816 * The same algorithm is used for senders.
817 */
818
819/* pipelined_send() - send a message directly to the task waiting in
820 * sys_mq_timedreceive() (without inserting message into a queue).
821 */
822static inline void pipelined_send(struct mqueue_inode_info *info,
823 struct msg_msg *message,
824 struct ext_wait_queue *receiver)
825{
826 receiver->msg = message;
827 list_del(&receiver->list);
828 receiver->state = STATE_PENDING;
829 wake_up_process(receiver->task);
830 smp_wmb();
831 receiver->state = STATE_READY;
832}
833
834/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
835 * gets its message and put to the queue (we have one free place for sure). */
836static inline void pipelined_receive(struct mqueue_inode_info *info)
837{
838 struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
839
840 if (!sender) {
841 /* for poll */
842 wake_up_interruptible(&info->wait_q);
843 return;
844 }
845 msg_insert(sender->msg, info);
846 list_del(&sender->list);
847 sender->state = STATE_PENDING;
848 wake_up_process(sender->task);
849 smp_wmb();
850 sender->state = STATE_READY;
851}
852
853SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
854 size_t, msg_len, unsigned int, msg_prio,
855 const struct timespec __user *, u_abs_timeout)
856{
857 struct file *filp;
858 struct inode *inode;
859 struct ext_wait_queue wait;
860 struct ext_wait_queue *receiver;
861 struct msg_msg *msg_ptr;
862 struct mqueue_inode_info *info;
863 ktime_t expires, *timeout = NULL;
864 struct timespec ts;
865 int ret;
866
867 if (u_abs_timeout) {
868 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
869 if (res)
870 return res;
871 timeout = &expires;
872 }
873
874 if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
875 return -EINVAL;
876
877 audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
878
879 filp = fget(mqdes);
880 if (unlikely(!filp)) {
881 ret = -EBADF;
882 goto out;
883 }
884
885 inode = filp->f_path.dentry->d_inode;
886 if (unlikely(filp->f_op != &mqueue_file_operations)) {
887 ret = -EBADF;
888 goto out_fput;
889 }
890 info = MQUEUE_I(inode);
891 audit_inode(NULL, filp->f_path.dentry);
892
893 if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
894 ret = -EBADF;
895 goto out_fput;
896 }
897
898 if (unlikely(msg_len > info->attr.mq_msgsize)) {
899 ret = -EMSGSIZE;
900 goto out_fput;
901 }
902
903 /* First try to allocate memory, before doing anything with
904 * existing queues. */
905 msg_ptr = load_msg(u_msg_ptr, msg_len);
906 if (IS_ERR(msg_ptr)) {
907 ret = PTR_ERR(msg_ptr);
908 goto out_fput;
909 }
910 msg_ptr->m_ts = msg_len;
911 msg_ptr->m_type = msg_prio;
912
913 spin_lock(&info->lock);
914
915 if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
916 if (filp->f_flags & O_NONBLOCK) {
917 spin_unlock(&info->lock);
918 ret = -EAGAIN;
919 } else {
920 wait.task = current;
921 wait.msg = (void *) msg_ptr;
922 wait.state = STATE_NONE;
923 ret = wq_sleep(info, SEND, timeout, &wait);
924 }
925 if (ret < 0)
926 free_msg(msg_ptr);
927 } else {
928 receiver = wq_get_first_waiter(info, RECV);
929 if (receiver) {
930 pipelined_send(info, msg_ptr, receiver);
931 } else {
932 /* adds message to the queue */
933 msg_insert(msg_ptr, info);
934 __do_notify(info);
935 }
936 inode->i_atime = inode->i_mtime = inode->i_ctime =
937 CURRENT_TIME;
938 spin_unlock(&info->lock);
939 ret = 0;
940 }
941out_fput:
942 fput(filp);
943out:
944 return ret;
945}
946
947SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
948 size_t, msg_len, unsigned int __user *, u_msg_prio,
949 const struct timespec __user *, u_abs_timeout)
950{
951 ssize_t ret;
952 struct msg_msg *msg_ptr;
953 struct file *filp;
954 struct inode *inode;
955 struct mqueue_inode_info *info;
956 struct ext_wait_queue wait;
957 ktime_t expires, *timeout = NULL;
958 struct timespec ts;
959
960 if (u_abs_timeout) {
961 int res = prepare_timeout(u_abs_timeout, &expires, &ts);
962 if (res)
963 return res;
964 timeout = &expires;
965 }
966
967 audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
968
969 filp = fget(mqdes);
970 if (unlikely(!filp)) {
971 ret = -EBADF;
972 goto out;
973 }
974
975 inode = filp->f_path.dentry->d_inode;
976 if (unlikely(filp->f_op != &mqueue_file_operations)) {
977 ret = -EBADF;
978 goto out_fput;
979 }
980 info = MQUEUE_I(inode);
981 audit_inode(NULL, filp->f_path.dentry);
982
983 if (unlikely(!(filp->f_mode & FMODE_READ))) {
984 ret = -EBADF;
985 goto out_fput;
986 }
987
988 /* checks if buffer is big enough */
989 if (unlikely(msg_len < info->attr.mq_msgsize)) {
990 ret = -EMSGSIZE;
991 goto out_fput;
992 }
993
994 spin_lock(&info->lock);
995 if (info->attr.mq_curmsgs == 0) {
996 if (filp->f_flags & O_NONBLOCK) {
997 spin_unlock(&info->lock);
998 ret = -EAGAIN;
999 } else {
1000 wait.task = current;
1001 wait.state = STATE_NONE;
1002 ret = wq_sleep(info, RECV, timeout, &wait);
1003 msg_ptr = wait.msg;
1004 }
1005 } else {
1006 msg_ptr = msg_get(info);
1007
1008 inode->i_atime = inode->i_mtime = inode->i_ctime =
1009 CURRENT_TIME;
1010
1011 /* There is now free space in queue. */
1012 pipelined_receive(info);
1013 spin_unlock(&info->lock);
1014 ret = 0;
1015 }
1016 if (ret == 0) {
1017 ret = msg_ptr->m_ts;
1018
1019 if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1020 store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1021 ret = -EFAULT;
1022 }
1023 free_msg(msg_ptr);
1024 }
1025out_fput:
1026 fput(filp);
1027out:
1028 return ret;
1029}
1030
1031/*
1032 * Notes: the case when user wants us to deregister (with NULL as pointer)
1033 * and he isn't currently owner of notification, will be silently discarded.
1034 * It isn't explicitly defined in the POSIX.
1035 */
1036SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1037 const struct sigevent __user *, u_notification)
1038{
1039 int ret;
1040 struct file *filp;
1041 struct sock *sock;
1042 struct inode *inode;
1043 struct sigevent notification;
1044 struct mqueue_inode_info *info;
1045 struct sk_buff *nc;
1046
1047 if (u_notification) {
1048 if (copy_from_user(&notification, u_notification,
1049 sizeof(struct sigevent)))
1050 return -EFAULT;
1051 }
1052
1053 audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1054
1055 nc = NULL;
1056 sock = NULL;
1057 if (u_notification != NULL) {
1058 if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1059 notification.sigev_notify != SIGEV_SIGNAL &&
1060 notification.sigev_notify != SIGEV_THREAD))
1061 return -EINVAL;
1062 if (notification.sigev_notify == SIGEV_SIGNAL &&
1063 !valid_signal(notification.sigev_signo)) {
1064 return -EINVAL;
1065 }
1066 if (notification.sigev_notify == SIGEV_THREAD) {
1067 long timeo;
1068
1069 /* create the notify skb */
1070 nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1071 if (!nc) {
1072 ret = -ENOMEM;
1073 goto out;
1074 }
1075 if (copy_from_user(nc->data,
1076 notification.sigev_value.sival_ptr,
1077 NOTIFY_COOKIE_LEN)) {
1078 ret = -EFAULT;
1079 goto out;
1080 }
1081
1082 /* TODO: add a header? */
1083 skb_put(nc, NOTIFY_COOKIE_LEN);
1084 /* and attach it to the socket */
1085retry:
1086 filp = fget(notification.sigev_signo);
1087 if (!filp) {
1088 ret = -EBADF;
1089 goto out;
1090 }
1091 sock = netlink_getsockbyfilp(filp);
1092 fput(filp);
1093 if (IS_ERR(sock)) {
1094 ret = PTR_ERR(sock);
1095 sock = NULL;
1096 goto out;
1097 }
1098
1099 timeo = MAX_SCHEDULE_TIMEOUT;
1100 ret = netlink_attachskb(sock, nc, &timeo, NULL);
1101 if (ret == 1)
1102 goto retry;
1103 if (ret) {
1104 sock = NULL;
1105 nc = NULL;
1106 goto out;
1107 }
1108 }
1109 }
1110
1111 filp = fget(mqdes);
1112 if (!filp) {
1113 ret = -EBADF;
1114 goto out;
1115 }
1116
1117 inode = filp->f_path.dentry->d_inode;
1118 if (unlikely(filp->f_op != &mqueue_file_operations)) {
1119 ret = -EBADF;
1120 goto out_fput;
1121 }
1122 info = MQUEUE_I(inode);
1123
1124 ret = 0;
1125 spin_lock(&info->lock);
1126 if (u_notification == NULL) {
1127 if (info->notify_owner == task_tgid(current)) {
1128 remove_notification(info);
1129 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1130 }
1131 } else if (info->notify_owner != NULL) {
1132 ret = -EBUSY;
1133 } else {
1134 switch (notification.sigev_notify) {
1135 case SIGEV_NONE:
1136 info->notify.sigev_notify = SIGEV_NONE;
1137 break;
1138 case SIGEV_THREAD:
1139 info->notify_sock = sock;
1140 info->notify_cookie = nc;
1141 sock = NULL;
1142 nc = NULL;
1143 info->notify.sigev_notify = SIGEV_THREAD;
1144 break;
1145 case SIGEV_SIGNAL:
1146 info->notify.sigev_signo = notification.sigev_signo;
1147 info->notify.sigev_value = notification.sigev_value;
1148 info->notify.sigev_notify = SIGEV_SIGNAL;
1149 break;
1150 }
1151
1152 info->notify_owner = get_pid(task_tgid(current));
1153 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1154 }
1155 spin_unlock(&info->lock);
1156out_fput:
1157 fput(filp);
1158out:
1159 if (sock) {
1160 netlink_detachskb(sock, nc);
1161 } else if (nc) {
1162 dev_kfree_skb(nc);
1163 }
1164 return ret;
1165}
1166
1167SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1168 const struct mq_attr __user *, u_mqstat,
1169 struct mq_attr __user *, u_omqstat)
1170{
1171 int ret;
1172 struct mq_attr mqstat, omqstat;
1173 struct file *filp;
1174 struct inode *inode;
1175 struct mqueue_inode_info *info;
1176
1177 if (u_mqstat != NULL) {
1178 if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1179 return -EFAULT;
1180 if (mqstat.mq_flags & (~O_NONBLOCK))
1181 return -EINVAL;
1182 }
1183
1184 filp = fget(mqdes);
1185 if (!filp) {
1186 ret = -EBADF;
1187 goto out;
1188 }
1189
1190 inode = filp->f_path.dentry->d_inode;
1191 if (unlikely(filp->f_op != &mqueue_file_operations)) {
1192 ret = -EBADF;
1193 goto out_fput;
1194 }
1195 info = MQUEUE_I(inode);
1196
1197 spin_lock(&info->lock);
1198
1199 omqstat = info->attr;
1200 omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1201 if (u_mqstat) {
1202 audit_mq_getsetattr(mqdes, &mqstat);
1203 spin_lock(&filp->f_lock);
1204 if (mqstat.mq_flags & O_NONBLOCK)
1205 filp->f_flags |= O_NONBLOCK;
1206 else
1207 filp->f_flags &= ~O_NONBLOCK;
1208 spin_unlock(&filp->f_lock);
1209
1210 inode->i_atime = inode->i_ctime = CURRENT_TIME;
1211 }
1212
1213 spin_unlock(&info->lock);
1214
1215 ret = 0;
1216 if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1217 sizeof(struct mq_attr)))
1218 ret = -EFAULT;
1219
1220out_fput:
1221 fput(filp);
1222out:
1223 return ret;
1224}
1225
1226static const struct inode_operations mqueue_dir_inode_operations = {
1227 .lookup = simple_lookup,
1228 .create = mqueue_create,
1229 .unlink = mqueue_unlink,
1230};
1231
1232static const struct file_operations mqueue_file_operations = {
1233 .flush = mqueue_flush_file,
1234 .poll = mqueue_poll_file,
1235 .read = mqueue_read_file,
1236 .llseek = default_llseek,
1237};
1238
1239static const struct super_operations mqueue_super_ops = {
1240 .alloc_inode = mqueue_alloc_inode,
1241 .destroy_inode = mqueue_destroy_inode,
1242 .evict_inode = mqueue_evict_inode,
1243 .statfs = simple_statfs,
1244};
1245
1246static struct file_system_type mqueue_fs_type = {
1247 .name = "mqueue",
1248 .mount = mqueue_mount,
1249 .kill_sb = kill_litter_super,
1250};
1251
1252int mq_init_ns(struct ipc_namespace *ns)
1253{
1254 ns->mq_queues_count = 0;
1255 ns->mq_queues_max = DFLT_QUEUESMAX;
1256 ns->mq_msg_max = DFLT_MSGMAX;
1257 ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1258
1259 ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1260 if (IS_ERR(ns->mq_mnt)) {
1261 int err = PTR_ERR(ns->mq_mnt);
1262 ns->mq_mnt = NULL;
1263 return err;
1264 }
1265 return 0;
1266}
1267
1268void mq_clear_sbinfo(struct ipc_namespace *ns)
1269{
1270 ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1271}
1272
1273void mq_put_mnt(struct ipc_namespace *ns)
1274{
1275 kern_unmount(ns->mq_mnt);
1276}
1277
1278static int __init init_mqueue_fs(void)
1279{
1280 int error;
1281
1282 mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1283 sizeof(struct mqueue_inode_info), 0,
1284 SLAB_HWCACHE_ALIGN, init_once);
1285 if (mqueue_inode_cachep == NULL)
1286 return -ENOMEM;
1287
1288 /* ignore failures - they are not fatal */
1289 mq_sysctl_table = mq_register_sysctl_table();
1290
1291 error = register_filesystem(&mqueue_fs_type);
1292 if (error)
1293 goto out_sysctl;
1294
1295 spin_lock_init(&mq_lock);
1296
1297 error = mq_init_ns(&init_ipc_ns);
1298 if (error)
1299 goto out_filesystem;
1300
1301 return 0;
1302
1303out_filesystem:
1304 unregister_filesystem(&mqueue_fs_type);
1305out_sysctl:
1306 if (mq_sysctl_table)
1307 unregister_sysctl_table(mq_sysctl_table);
1308 kmem_cache_destroy(mqueue_inode_cachep);
1309 return error;
1310}
1311
1312__initcall(init_mqueue_fs);