Root/ipc/mqueue.c

1/*
2 * POSIX message queues filesystem for Linux.
3 *
4 * Copyright (C) 2003,2004 Krzysztof Benedyczak (golbi@mat.uni.torun.pl)
5 * Michal Wronski (michal.wronski@gmail.com)
6 *
7 * Spinlocks: Mohamed Abbas (abbas.mohamed@intel.com)
8 * Lockless receive & send, fd based notify:
9 * Manfred Spraul (manfred@colorfullife.com)
10 *
11 * Audit: George Wilson (ltcgcw@us.ibm.com)
12 *
13 * This file is released under the GPL.
14 */
15
16#include <linux/capability.h>
17#include <linux/init.h>
18#include <linux/pagemap.h>
19#include <linux/file.h>
20#include <linux/mount.h>
21#include <linux/namei.h>
22#include <linux/sysctl.h>
23#include <linux/poll.h>
24#include <linux/mqueue.h>
25#include <linux/msg.h>
26#include <linux/skbuff.h>
27#include <linux/vmalloc.h>
28#include <linux/netlink.h>
29#include <linux/syscalls.h>
30#include <linux/audit.h>
31#include <linux/signal.h>
32#include <linux/mutex.h>
33#include <linux/nsproxy.h>
34#include <linux/pid.h>
35#include <linux/ipc_namespace.h>
36#include <linux/user_namespace.h>
37#include <linux/slab.h>
38
39#include <net/sock.h>
40#include "util.h"
41
42#define MQUEUE_MAGIC 0x19800202
43#define DIRENT_SIZE 20
44#define FILENT_SIZE 80
45
46#define SEND 0
47#define RECV 1
48
49#define STATE_NONE 0
50#define STATE_PENDING 1
51#define STATE_READY 2
52
53struct posix_msg_tree_node {
54    struct rb_node rb_node;
55    struct list_head msg_list;
56    int priority;
57};
58
59struct ext_wait_queue { /* queue of sleeping tasks */
60    struct task_struct *task;
61    struct list_head list;
62    struct msg_msg *msg; /* ptr of loaded message */
63    int state; /* one of STATE_* values */
64};
65
66struct mqueue_inode_info {
67    spinlock_t lock;
68    struct inode vfs_inode;
69    wait_queue_head_t wait_q;
70
71    struct rb_root msg_tree;
72    struct posix_msg_tree_node *node_cache;
73    struct mq_attr attr;
74
75    struct sigevent notify;
76    struct pid *notify_owner;
77    struct user_namespace *notify_user_ns;
78    struct user_struct *user; /* user who created, for accounting */
79    struct sock *notify_sock;
80    struct sk_buff *notify_cookie;
81
82    /* for tasks waiting for free space and messages, respectively */
83    struct ext_wait_queue e_wait_q[2];
84
85    unsigned long qsize; /* size of queue in memory (sum of all msgs) */
86};
87
88static const struct inode_operations mqueue_dir_inode_operations;
89static const struct file_operations mqueue_file_operations;
90static const struct super_operations mqueue_super_ops;
91static void remove_notification(struct mqueue_inode_info *info);
92
93static struct kmem_cache *mqueue_inode_cachep;
94
95static struct ctl_table_header *mq_sysctl_table;
96
97static inline struct mqueue_inode_info *MQUEUE_I(struct inode *inode)
98{
99    return container_of(inode, struct mqueue_inode_info, vfs_inode);
100}
101
102/*
103 * This routine should be called with the mq_lock held.
104 */
105static inline struct ipc_namespace *__get_ns_from_inode(struct inode *inode)
106{
107    return get_ipc_ns(inode->i_sb->s_fs_info);
108}
109
110static struct ipc_namespace *get_ns_from_inode(struct inode *inode)
111{
112    struct ipc_namespace *ns;
113
114    spin_lock(&mq_lock);
115    ns = __get_ns_from_inode(inode);
116    spin_unlock(&mq_lock);
117    return ns;
118}
119
120/* Auxiliary functions to manipulate messages' list */
121static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
122{
123    struct rb_node **p, *parent = NULL;
124    struct posix_msg_tree_node *leaf;
125
126    p = &info->msg_tree.rb_node;
127    while (*p) {
128        parent = *p;
129        leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
130
131        if (likely(leaf->priority == msg->m_type))
132            goto insert_msg;
133        else if (msg->m_type < leaf->priority)
134            p = &(*p)->rb_left;
135        else
136            p = &(*p)->rb_right;
137    }
138    if (info->node_cache) {
139        leaf = info->node_cache;
140        info->node_cache = NULL;
141    } else {
142        leaf = kmalloc(sizeof(*leaf), GFP_ATOMIC);
143        if (!leaf)
144            return -ENOMEM;
145        INIT_LIST_HEAD(&leaf->msg_list);
146        info->qsize += sizeof(*leaf);
147    }
148    leaf->priority = msg->m_type;
149    rb_link_node(&leaf->rb_node, parent, p);
150    rb_insert_color(&leaf->rb_node, &info->msg_tree);
151insert_msg:
152    info->attr.mq_curmsgs++;
153    info->qsize += msg->m_ts;
154    list_add_tail(&msg->m_list, &leaf->msg_list);
155    return 0;
156}
157
158static inline struct msg_msg *msg_get(struct mqueue_inode_info *info)
159{
160    struct rb_node **p, *parent = NULL;
161    struct posix_msg_tree_node *leaf;
162    struct msg_msg *msg;
163
164try_again:
165    p = &info->msg_tree.rb_node;
166    while (*p) {
167        parent = *p;
168        /*
169         * During insert, low priorities go to the left and high to the
170         * right. On receive, we want the highest priorities first, so
171         * walk all the way to the right.
172         */
173        p = &(*p)->rb_right;
174    }
175    if (!parent) {
176        if (info->attr.mq_curmsgs) {
177            pr_warn_once("Inconsistency in POSIX message queue, "
178                     "no tree element, but supposedly messages "
179                     "should exist!\n");
180            info->attr.mq_curmsgs = 0;
181        }
182        return NULL;
183    }
184    leaf = rb_entry(parent, struct posix_msg_tree_node, rb_node);
185    if (unlikely(list_empty(&leaf->msg_list))) {
186        pr_warn_once("Inconsistency in POSIX message queue, "
187                 "empty leaf node but we haven't implemented "
188                 "lazy leaf delete!\n");
189        rb_erase(&leaf->rb_node, &info->msg_tree);
190        if (info->node_cache) {
191            info->qsize -= sizeof(*leaf);
192            kfree(leaf);
193        } else {
194            info->node_cache = leaf;
195        }
196        goto try_again;
197    } else {
198        msg = list_first_entry(&leaf->msg_list,
199                       struct msg_msg, m_list);
200        list_del(&msg->m_list);
201        if (list_empty(&leaf->msg_list)) {
202            rb_erase(&leaf->rb_node, &info->msg_tree);
203            if (info->node_cache) {
204                info->qsize -= sizeof(*leaf);
205                kfree(leaf);
206            } else {
207                info->node_cache = leaf;
208            }
209        }
210    }
211    info->attr.mq_curmsgs--;
212    info->qsize -= msg->m_ts;
213    return msg;
214}
215
216static struct inode *mqueue_get_inode(struct super_block *sb,
217        struct ipc_namespace *ipc_ns, umode_t mode,
218        struct mq_attr *attr)
219{
220    struct user_struct *u = current_user();
221    struct inode *inode;
222    int ret = -ENOMEM;
223
224    inode = new_inode(sb);
225    if (!inode)
226        goto err;
227
228    inode->i_ino = get_next_ino();
229    inode->i_mode = mode;
230    inode->i_uid = current_fsuid();
231    inode->i_gid = current_fsgid();
232    inode->i_mtime = inode->i_ctime = inode->i_atime = CURRENT_TIME;
233
234    if (S_ISREG(mode)) {
235        struct mqueue_inode_info *info;
236        unsigned long mq_bytes, mq_treesize;
237
238        inode->i_fop = &mqueue_file_operations;
239        inode->i_size = FILENT_SIZE;
240        /* mqueue specific info */
241        info = MQUEUE_I(inode);
242        spin_lock_init(&info->lock);
243        init_waitqueue_head(&info->wait_q);
244        INIT_LIST_HEAD(&info->e_wait_q[0].list);
245        INIT_LIST_HEAD(&info->e_wait_q[1].list);
246        info->notify_owner = NULL;
247        info->notify_user_ns = NULL;
248        info->qsize = 0;
249        info->user = NULL; /* set when all is ok */
250        info->msg_tree = RB_ROOT;
251        info->node_cache = NULL;
252        memset(&info->attr, 0, sizeof(info->attr));
253        info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
254                       ipc_ns->mq_msg_default);
255        info->attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
256                        ipc_ns->mq_msgsize_default);
257        if (attr) {
258            info->attr.mq_maxmsg = attr->mq_maxmsg;
259            info->attr.mq_msgsize = attr->mq_msgsize;
260        }
261        /*
262         * We used to allocate a static array of pointers and account
263         * the size of that array as well as one msg_msg struct per
264         * possible message into the queue size. That's no longer
265         * accurate as the queue is now an rbtree and will grow and
266         * shrink depending on usage patterns. We can, however, still
267         * account one msg_msg struct per message, but the nodes are
268         * allocated depending on priority usage, and most programs
269         * only use one, or a handful, of priorities. However, since
270         * this is pinned memory, we need to assume worst case, so
271         * that means the min(mq_maxmsg, max_priorities) * struct
272         * posix_msg_tree_node.
273         */
274        mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
275            min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
276            sizeof(struct posix_msg_tree_node);
277
278        mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
279                      info->attr.mq_msgsize);
280
281        spin_lock(&mq_lock);
282        if (u->mq_bytes + mq_bytes < u->mq_bytes ||
283            u->mq_bytes + mq_bytes > rlimit(RLIMIT_MSGQUEUE)) {
284            spin_unlock(&mq_lock);
285            /* mqueue_evict_inode() releases info->messages */
286            ret = -EMFILE;
287            goto out_inode;
288        }
289        u->mq_bytes += mq_bytes;
290        spin_unlock(&mq_lock);
291
292        /* all is ok */
293        info->user = get_uid(u);
294    } else if (S_ISDIR(mode)) {
295        inc_nlink(inode);
296        /* Some things misbehave if size == 0 on a directory */
297        inode->i_size = 2 * DIRENT_SIZE;
298        inode->i_op = &mqueue_dir_inode_operations;
299        inode->i_fop = &simple_dir_operations;
300    }
301
302    return inode;
303out_inode:
304    iput(inode);
305err:
306    return ERR_PTR(ret);
307}
308
309static int mqueue_fill_super(struct super_block *sb, void *data, int silent)
310{
311    struct inode *inode;
312    struct ipc_namespace *ns = data;
313
314    sb->s_blocksize = PAGE_CACHE_SIZE;
315    sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
316    sb->s_magic = MQUEUE_MAGIC;
317    sb->s_op = &mqueue_super_ops;
318
319    inode = mqueue_get_inode(sb, ns, S_IFDIR | S_ISVTX | S_IRWXUGO, NULL);
320    if (IS_ERR(inode))
321        return PTR_ERR(inode);
322
323    sb->s_root = d_make_root(inode);
324    if (!sb->s_root)
325        return -ENOMEM;
326    return 0;
327}
328
329static struct dentry *mqueue_mount(struct file_system_type *fs_type,
330             int flags, const char *dev_name,
331             void *data)
332{
333    if (!(flags & MS_KERNMOUNT)) {
334        struct ipc_namespace *ns = current->nsproxy->ipc_ns;
335        /* Don't allow mounting unless the caller has CAP_SYS_ADMIN
336         * over the ipc namespace.
337         */
338        if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))
339            return ERR_PTR(-EPERM);
340
341        data = ns;
342    }
343    return mount_ns(fs_type, flags, data, mqueue_fill_super);
344}
345
346static void init_once(void *foo)
347{
348    struct mqueue_inode_info *p = (struct mqueue_inode_info *) foo;
349
350    inode_init_once(&p->vfs_inode);
351}
352
353static struct inode *mqueue_alloc_inode(struct super_block *sb)
354{
355    struct mqueue_inode_info *ei;
356
357    ei = kmem_cache_alloc(mqueue_inode_cachep, GFP_KERNEL);
358    if (!ei)
359        return NULL;
360    return &ei->vfs_inode;
361}
362
363static void mqueue_i_callback(struct rcu_head *head)
364{
365    struct inode *inode = container_of(head, struct inode, i_rcu);
366    kmem_cache_free(mqueue_inode_cachep, MQUEUE_I(inode));
367}
368
369static void mqueue_destroy_inode(struct inode *inode)
370{
371    call_rcu(&inode->i_rcu, mqueue_i_callback);
372}
373
374static void mqueue_evict_inode(struct inode *inode)
375{
376    struct mqueue_inode_info *info;
377    struct user_struct *user;
378    unsigned long mq_bytes, mq_treesize;
379    struct ipc_namespace *ipc_ns;
380    struct msg_msg *msg;
381
382    clear_inode(inode);
383
384    if (S_ISDIR(inode->i_mode))
385        return;
386
387    ipc_ns = get_ns_from_inode(inode);
388    info = MQUEUE_I(inode);
389    spin_lock(&info->lock);
390    while ((msg = msg_get(info)) != NULL)
391        free_msg(msg);
392    kfree(info->node_cache);
393    spin_unlock(&info->lock);
394
395    /* Total amount of bytes accounted for the mqueue */
396    mq_treesize = info->attr.mq_maxmsg * sizeof(struct msg_msg) +
397        min_t(unsigned int, info->attr.mq_maxmsg, MQ_PRIO_MAX) *
398        sizeof(struct posix_msg_tree_node);
399
400    mq_bytes = mq_treesize + (info->attr.mq_maxmsg *
401                  info->attr.mq_msgsize);
402
403    user = info->user;
404    if (user) {
405        spin_lock(&mq_lock);
406        user->mq_bytes -= mq_bytes;
407        /*
408         * get_ns_from_inode() ensures that the
409         * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
410         * to which we now hold a reference, or it is NULL.
411         * We can't put it here under mq_lock, though.
412         */
413        if (ipc_ns)
414            ipc_ns->mq_queues_count--;
415        spin_unlock(&mq_lock);
416        free_uid(user);
417    }
418    if (ipc_ns)
419        put_ipc_ns(ipc_ns);
420}
421
422static int mqueue_create(struct inode *dir, struct dentry *dentry,
423                umode_t mode, bool excl)
424{
425    struct inode *inode;
426    struct mq_attr *attr = dentry->d_fsdata;
427    int error;
428    struct ipc_namespace *ipc_ns;
429
430    spin_lock(&mq_lock);
431    ipc_ns = __get_ns_from_inode(dir);
432    if (!ipc_ns) {
433        error = -EACCES;
434        goto out_unlock;
435    }
436
437    if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
438        !capable(CAP_SYS_RESOURCE)) {
439        error = -ENOSPC;
440        goto out_unlock;
441    }
442    ipc_ns->mq_queues_count++;
443    spin_unlock(&mq_lock);
444
445    inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
446    if (IS_ERR(inode)) {
447        error = PTR_ERR(inode);
448        spin_lock(&mq_lock);
449        ipc_ns->mq_queues_count--;
450        goto out_unlock;
451    }
452
453    put_ipc_ns(ipc_ns);
454    dir->i_size += DIRENT_SIZE;
455    dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
456
457    d_instantiate(dentry, inode);
458    dget(dentry);
459    return 0;
460out_unlock:
461    spin_unlock(&mq_lock);
462    if (ipc_ns)
463        put_ipc_ns(ipc_ns);
464    return error;
465}
466
467static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
468{
469    struct inode *inode = dentry->d_inode;
470
471    dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
472    dir->i_size -= DIRENT_SIZE;
473    drop_nlink(inode);
474    dput(dentry);
475    return 0;
476}
477
478/*
479* This is routine for system read from queue file.
480* To avoid mess with doing here some sort of mq_receive we allow
481* to read only queue size & notification info (the only values
482* that are interesting from user point of view and aren't accessible
483* through std routines)
484*/
485static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
486                size_t count, loff_t *off)
487{
488    struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
489    char buffer[FILENT_SIZE];
490    ssize_t ret;
491
492    spin_lock(&info->lock);
493    snprintf(buffer, sizeof(buffer),
494            "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
495            info->qsize,
496            info->notify_owner ? info->notify.sigev_notify : 0,
497            (info->notify_owner &&
498             info->notify.sigev_notify == SIGEV_SIGNAL) ?
499                info->notify.sigev_signo : 0,
500            pid_vnr(info->notify_owner));
501    spin_unlock(&info->lock);
502    buffer[sizeof(buffer)-1] = '\0';
503
504    ret = simple_read_from_buffer(u_data, count, off, buffer,
505                strlen(buffer));
506    if (ret <= 0)
507        return ret;
508
509    file_inode(filp)->i_atime = file_inode(filp)->i_ctime = CURRENT_TIME;
510    return ret;
511}
512
513static int mqueue_flush_file(struct file *filp, fl_owner_t id)
514{
515    struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
516
517    spin_lock(&info->lock);
518    if (task_tgid(current) == info->notify_owner)
519        remove_notification(info);
520
521    spin_unlock(&info->lock);
522    return 0;
523}
524
525static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
526{
527    struct mqueue_inode_info *info = MQUEUE_I(file_inode(filp));
528    int retval = 0;
529
530    poll_wait(filp, &info->wait_q, poll_tab);
531
532    spin_lock(&info->lock);
533    if (info->attr.mq_curmsgs)
534        retval = POLLIN | POLLRDNORM;
535
536    if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
537        retval |= POLLOUT | POLLWRNORM;
538    spin_unlock(&info->lock);
539
540    return retval;
541}
542
543/* Adds current to info->e_wait_q[sr] before element with smaller prio */
544static void wq_add(struct mqueue_inode_info *info, int sr,
545            struct ext_wait_queue *ewp)
546{
547    struct ext_wait_queue *walk;
548
549    ewp->task = current;
550
551    list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
552        if (walk->task->static_prio <= current->static_prio) {
553            list_add_tail(&ewp->list, &walk->list);
554            return;
555        }
556    }
557    list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
558}
559
560/*
561 * Puts current task to sleep. Caller must hold queue lock. After return
562 * lock isn't held.
563 * sr: SEND or RECV
564 */
565static int wq_sleep(struct mqueue_inode_info *info, int sr,
566            ktime_t *timeout, struct ext_wait_queue *ewp)
567{
568    int retval;
569    signed long time;
570
571    wq_add(info, sr, ewp);
572
573    for (;;) {
574        set_current_state(TASK_INTERRUPTIBLE);
575
576        spin_unlock(&info->lock);
577        time = schedule_hrtimeout_range_clock(timeout, 0,
578            HRTIMER_MODE_ABS, CLOCK_REALTIME);
579
580        while (ewp->state == STATE_PENDING)
581            cpu_relax();
582
583        if (ewp->state == STATE_READY) {
584            retval = 0;
585            goto out;
586        }
587        spin_lock(&info->lock);
588        if (ewp->state == STATE_READY) {
589            retval = 0;
590            goto out_unlock;
591        }
592        if (signal_pending(current)) {
593            retval = -ERESTARTSYS;
594            break;
595        }
596        if (time == 0) {
597            retval = -ETIMEDOUT;
598            break;
599        }
600    }
601    list_del(&ewp->list);
602out_unlock:
603    spin_unlock(&info->lock);
604out:
605    return retval;
606}
607
608/*
609 * Returns waiting task that should be serviced first or NULL if none exists
610 */
611static struct ext_wait_queue *wq_get_first_waiter(
612        struct mqueue_inode_info *info, int sr)
613{
614    struct list_head *ptr;
615
616    ptr = info->e_wait_q[sr].list.prev;
617    if (ptr == &info->e_wait_q[sr].list)
618        return NULL;
619    return list_entry(ptr, struct ext_wait_queue, list);
620}
621
622
623static inline void set_cookie(struct sk_buff *skb, char code)
624{
625    ((char *)skb->data)[NOTIFY_COOKIE_LEN-1] = code;
626}
627
628/*
629 * The next function is only to split too long sys_mq_timedsend
630 */
631static void __do_notify(struct mqueue_inode_info *info)
632{
633    /* notification
634     * invoked when there is registered process and there isn't process
635     * waiting synchronously for message AND state of queue changed from
636     * empty to not empty. Here we are sure that no one is waiting
637     * synchronously. */
638    if (info->notify_owner &&
639        info->attr.mq_curmsgs == 1) {
640        struct siginfo sig_i;
641        switch (info->notify.sigev_notify) {
642        case SIGEV_NONE:
643            break;
644        case SIGEV_SIGNAL:
645            /* sends signal */
646
647            sig_i.si_signo = info->notify.sigev_signo;
648            sig_i.si_errno = 0;
649            sig_i.si_code = SI_MESGQ;
650            sig_i.si_value = info->notify.sigev_value;
651            /* map current pid/uid into info->owner's namespaces */
652            rcu_read_lock();
653            sig_i.si_pid = task_tgid_nr_ns(current,
654                        ns_of_pid(info->notify_owner));
655            sig_i.si_uid = from_kuid_munged(info->notify_user_ns, current_uid());
656            rcu_read_unlock();
657
658            kill_pid_info(info->notify.sigev_signo,
659                      &sig_i, info->notify_owner);
660            break;
661        case SIGEV_THREAD:
662            set_cookie(info->notify_cookie, NOTIFY_WOKENUP);
663            netlink_sendskb(info->notify_sock, info->notify_cookie);
664            break;
665        }
666        /* after notification unregisters process */
667        put_pid(info->notify_owner);
668        put_user_ns(info->notify_user_ns);
669        info->notify_owner = NULL;
670        info->notify_user_ns = NULL;
671    }
672    wake_up(&info->wait_q);
673}
674
675static int prepare_timeout(const struct timespec __user *u_abs_timeout,
676               ktime_t *expires, struct timespec *ts)
677{
678    if (copy_from_user(ts, u_abs_timeout, sizeof(struct timespec)))
679        return -EFAULT;
680    if (!timespec_valid(ts))
681        return -EINVAL;
682
683    *expires = timespec_to_ktime(*ts);
684    return 0;
685}
686
687static void remove_notification(struct mqueue_inode_info *info)
688{
689    if (info->notify_owner != NULL &&
690        info->notify.sigev_notify == SIGEV_THREAD) {
691        set_cookie(info->notify_cookie, NOTIFY_REMOVED);
692        netlink_sendskb(info->notify_sock, info->notify_cookie);
693    }
694    put_pid(info->notify_owner);
695    put_user_ns(info->notify_user_ns);
696    info->notify_owner = NULL;
697    info->notify_user_ns = NULL;
698}
699
700static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
701{
702    int mq_treesize;
703    unsigned long total_size;
704
705    if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
706        return -EINVAL;
707    if (capable(CAP_SYS_RESOURCE)) {
708        if (attr->mq_maxmsg > HARD_MSGMAX ||
709            attr->mq_msgsize > HARD_MSGSIZEMAX)
710            return -EINVAL;
711    } else {
712        if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
713                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
714            return -EINVAL;
715    }
716    /* check for overflow */
717    if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
718        return -EOVERFLOW;
719    mq_treesize = attr->mq_maxmsg * sizeof(struct msg_msg) +
720        min_t(unsigned int, attr->mq_maxmsg, MQ_PRIO_MAX) *
721        sizeof(struct posix_msg_tree_node);
722    total_size = attr->mq_maxmsg * attr->mq_msgsize;
723    if (total_size + mq_treesize < total_size)
724        return -EOVERFLOW;
725    return 0;
726}
727
728/*
729 * Invoked when creating a new queue via sys_mq_open
730 */
731static struct file *do_create(struct ipc_namespace *ipc_ns, struct inode *dir,
732            struct path *path, int oflag, umode_t mode,
733            struct mq_attr *attr)
734{
735    const struct cred *cred = current_cred();
736    int ret;
737
738    if (attr) {
739        ret = mq_attr_ok(ipc_ns, attr);
740        if (ret)
741            return ERR_PTR(ret);
742        /* store for use during create */
743        path->dentry->d_fsdata = attr;
744    } else {
745        struct mq_attr def_attr;
746
747        def_attr.mq_maxmsg = min(ipc_ns->mq_msg_max,
748                     ipc_ns->mq_msg_default);
749        def_attr.mq_msgsize = min(ipc_ns->mq_msgsize_max,
750                      ipc_ns->mq_msgsize_default);
751        ret = mq_attr_ok(ipc_ns, &def_attr);
752        if (ret)
753            return ERR_PTR(ret);
754    }
755
756    mode &= ~current_umask();
757    ret = vfs_create(dir, path->dentry, mode, true);
758    path->dentry->d_fsdata = NULL;
759    if (ret)
760        return ERR_PTR(ret);
761    return dentry_open(path, oflag, cred);
762}
763
764/* Opens existing queue */
765static struct file *do_open(struct path *path, int oflag)
766{
767    static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
768                          MAY_READ | MAY_WRITE };
769    int acc;
770    if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY))
771        return ERR_PTR(-EINVAL);
772    acc = oflag2acc[oflag & O_ACCMODE];
773    if (inode_permission(path->dentry->d_inode, acc))
774        return ERR_PTR(-EACCES);
775    return dentry_open(path, oflag, current_cred());
776}
777
778SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
779        struct mq_attr __user *, u_attr)
780{
781    struct path path;
782    struct file *filp;
783    struct filename *name;
784    struct mq_attr attr;
785    int fd, error;
786    struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
787    struct vfsmount *mnt = ipc_ns->mq_mnt;
788    struct dentry *root = mnt->mnt_root;
789    int ro;
790
791    if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
792        return -EFAULT;
793
794    audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
795
796    if (IS_ERR(name = getname(u_name)))
797        return PTR_ERR(name);
798
799    fd = get_unused_fd_flags(O_CLOEXEC);
800    if (fd < 0)
801        goto out_putname;
802
803    ro = mnt_want_write(mnt); /* we'll drop it in any case */
804    error = 0;
805    mutex_lock(&root->d_inode->i_mutex);
806    path.dentry = lookup_one_len(name->name, root, strlen(name->name));
807    if (IS_ERR(path.dentry)) {
808        error = PTR_ERR(path.dentry);
809        goto out_putfd;
810    }
811    path.mnt = mntget(mnt);
812
813    if (oflag & O_CREAT) {
814        if (path.dentry->d_inode) { /* entry already exists */
815            audit_inode(name, path.dentry, 0);
816            if (oflag & O_EXCL) {
817                error = -EEXIST;
818                goto out;
819            }
820            filp = do_open(&path, oflag);
821        } else {
822            if (ro) {
823                error = ro;
824                goto out;
825            }
826            audit_inode_parent_hidden(name, root);
827            filp = do_create(ipc_ns, root->d_inode,
828                        &path, oflag, mode,
829                        u_attr ? &attr : NULL);
830        }
831    } else {
832        if (!path.dentry->d_inode) {
833            error = -ENOENT;
834            goto out;
835        }
836        audit_inode(name, path.dentry, 0);
837        filp = do_open(&path, oflag);
838    }
839
840    if (!IS_ERR(filp))
841        fd_install(fd, filp);
842    else
843        error = PTR_ERR(filp);
844out:
845    path_put(&path);
846out_putfd:
847    if (error) {
848        put_unused_fd(fd);
849        fd = error;
850    }
851    mutex_unlock(&root->d_inode->i_mutex);
852    if (!ro)
853        mnt_drop_write(mnt);
854out_putname:
855    putname(name);
856    return fd;
857}
858
859SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
860{
861    int err;
862    struct filename *name;
863    struct dentry *dentry;
864    struct inode *inode = NULL;
865    struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
866    struct vfsmount *mnt = ipc_ns->mq_mnt;
867
868    name = getname(u_name);
869    if (IS_ERR(name))
870        return PTR_ERR(name);
871
872    audit_inode_parent_hidden(name, mnt->mnt_root);
873    err = mnt_want_write(mnt);
874    if (err)
875        goto out_name;
876    mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
877    dentry = lookup_one_len(name->name, mnt->mnt_root,
878                strlen(name->name));
879    if (IS_ERR(dentry)) {
880        err = PTR_ERR(dentry);
881        goto out_unlock;
882    }
883
884    inode = dentry->d_inode;
885    if (!inode) {
886        err = -ENOENT;
887    } else {
888        ihold(inode);
889        err = vfs_unlink(dentry->d_parent->d_inode, dentry, NULL);
890    }
891    dput(dentry);
892
893out_unlock:
894    mutex_unlock(&mnt->mnt_root->d_inode->i_mutex);
895    if (inode)
896        iput(inode);
897    mnt_drop_write(mnt);
898out_name:
899    putname(name);
900
901    return err;
902}
903
904/* Pipelined send and receive functions.
905 *
906 * If a receiver finds no waiting message, then it registers itself in the
907 * list of waiting receivers. A sender checks that list before adding the new
908 * message into the message array. If there is a waiting receiver, then it
909 * bypasses the message array and directly hands the message over to the
910 * receiver.
911 * The receiver accepts the message and returns without grabbing the queue
912 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
913 * are necessary. The same algorithm is used for sysv semaphores, see
914 * ipc/sem.c for more details.
915 *
916 * The same algorithm is used for senders.
917 */
918
919/* pipelined_send() - send a message directly to the task waiting in
920 * sys_mq_timedreceive() (without inserting message into a queue).
921 */
922static inline void pipelined_send(struct mqueue_inode_info *info,
923                  struct msg_msg *message,
924                  struct ext_wait_queue *receiver)
925{
926    receiver->msg = message;
927    list_del(&receiver->list);
928    receiver->state = STATE_PENDING;
929    wake_up_process(receiver->task);
930    smp_wmb();
931    receiver->state = STATE_READY;
932}
933
934/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
935 * gets its message and put to the queue (we have one free place for sure). */
936static inline void pipelined_receive(struct mqueue_inode_info *info)
937{
938    struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
939
940    if (!sender) {
941        /* for poll */
942        wake_up_interruptible(&info->wait_q);
943        return;
944    }
945    if (msg_insert(sender->msg, info))
946        return;
947    list_del(&sender->list);
948    sender->state = STATE_PENDING;
949    wake_up_process(sender->task);
950    smp_wmb();
951    sender->state = STATE_READY;
952}
953
954SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
955        size_t, msg_len, unsigned int, msg_prio,
956        const struct timespec __user *, u_abs_timeout)
957{
958    struct fd f;
959    struct inode *inode;
960    struct ext_wait_queue wait;
961    struct ext_wait_queue *receiver;
962    struct msg_msg *msg_ptr;
963    struct mqueue_inode_info *info;
964    ktime_t expires, *timeout = NULL;
965    struct timespec ts;
966    struct posix_msg_tree_node *new_leaf = NULL;
967    int ret = 0;
968
969    if (u_abs_timeout) {
970        int res = prepare_timeout(u_abs_timeout, &expires, &ts);
971        if (res)
972            return res;
973        timeout = &expires;
974    }
975
976    if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
977        return -EINVAL;
978
979    audit_mq_sendrecv(mqdes, msg_len, msg_prio, timeout ? &ts : NULL);
980
981    f = fdget(mqdes);
982    if (unlikely(!f.file)) {
983        ret = -EBADF;
984        goto out;
985    }
986
987    inode = file_inode(f.file);
988    if (unlikely(f.file->f_op != &mqueue_file_operations)) {
989        ret = -EBADF;
990        goto out_fput;
991    }
992    info = MQUEUE_I(inode);
993    audit_inode(NULL, f.file->f_path.dentry, 0);
994
995    if (unlikely(!(f.file->f_mode & FMODE_WRITE))) {
996        ret = -EBADF;
997        goto out_fput;
998    }
999
1000    if (unlikely(msg_len > info->attr.mq_msgsize)) {
1001        ret = -EMSGSIZE;
1002        goto out_fput;
1003    }
1004
1005    /* First try to allocate memory, before doing anything with
1006     * existing queues. */
1007    msg_ptr = load_msg(u_msg_ptr, msg_len);
1008    if (IS_ERR(msg_ptr)) {
1009        ret = PTR_ERR(msg_ptr);
1010        goto out_fput;
1011    }
1012    msg_ptr->m_ts = msg_len;
1013    msg_ptr->m_type = msg_prio;
1014
1015    /*
1016     * msg_insert really wants us to have a valid, spare node struct so
1017     * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1018     * fall back to that if necessary.
1019     */
1020    if (!info->node_cache)
1021        new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1022
1023    spin_lock(&info->lock);
1024
1025    if (!info->node_cache && new_leaf) {
1026        /* Save our speculative allocation into the cache */
1027        INIT_LIST_HEAD(&new_leaf->msg_list);
1028        info->node_cache = new_leaf;
1029        info->qsize += sizeof(*new_leaf);
1030        new_leaf = NULL;
1031    } else {
1032        kfree(new_leaf);
1033    }
1034
1035    if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
1036        if (f.file->f_flags & O_NONBLOCK) {
1037            ret = -EAGAIN;
1038        } else {
1039            wait.task = current;
1040            wait.msg = (void *) msg_ptr;
1041            wait.state = STATE_NONE;
1042            ret = wq_sleep(info, SEND, timeout, &wait);
1043            /*
1044             * wq_sleep must be called with info->lock held, and
1045             * returns with the lock released
1046             */
1047            goto out_free;
1048        }
1049    } else {
1050        receiver = wq_get_first_waiter(info, RECV);
1051        if (receiver) {
1052            pipelined_send(info, msg_ptr, receiver);
1053        } else {
1054            /* adds message to the queue */
1055            ret = msg_insert(msg_ptr, info);
1056            if (ret)
1057                goto out_unlock;
1058            __do_notify(info);
1059        }
1060        inode->i_atime = inode->i_mtime = inode->i_ctime =
1061                CURRENT_TIME;
1062    }
1063out_unlock:
1064    spin_unlock(&info->lock);
1065out_free:
1066    if (ret)
1067        free_msg(msg_ptr);
1068out_fput:
1069    fdput(f);
1070out:
1071    return ret;
1072}
1073
1074SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
1075        size_t, msg_len, unsigned int __user *, u_msg_prio,
1076        const struct timespec __user *, u_abs_timeout)
1077{
1078    ssize_t ret;
1079    struct msg_msg *msg_ptr;
1080    struct fd f;
1081    struct inode *inode;
1082    struct mqueue_inode_info *info;
1083    struct ext_wait_queue wait;
1084    ktime_t expires, *timeout = NULL;
1085    struct timespec ts;
1086    struct posix_msg_tree_node *new_leaf = NULL;
1087
1088    if (u_abs_timeout) {
1089        int res = prepare_timeout(u_abs_timeout, &expires, &ts);
1090        if (res)
1091            return res;
1092        timeout = &expires;
1093    }
1094
1095    audit_mq_sendrecv(mqdes, msg_len, 0, timeout ? &ts : NULL);
1096
1097    f = fdget(mqdes);
1098    if (unlikely(!f.file)) {
1099        ret = -EBADF;
1100        goto out;
1101    }
1102
1103    inode = file_inode(f.file);
1104    if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1105        ret = -EBADF;
1106        goto out_fput;
1107    }
1108    info = MQUEUE_I(inode);
1109    audit_inode(NULL, f.file->f_path.dentry, 0);
1110
1111    if (unlikely(!(f.file->f_mode & FMODE_READ))) {
1112        ret = -EBADF;
1113        goto out_fput;
1114    }
1115
1116    /* checks if buffer is big enough */
1117    if (unlikely(msg_len < info->attr.mq_msgsize)) {
1118        ret = -EMSGSIZE;
1119        goto out_fput;
1120    }
1121
1122    /*
1123     * msg_insert really wants us to have a valid, spare node struct so
1124     * it doesn't have to kmalloc a GFP_ATOMIC allocation, but it will
1125     * fall back to that if necessary.
1126     */
1127    if (!info->node_cache)
1128        new_leaf = kmalloc(sizeof(*new_leaf), GFP_KERNEL);
1129
1130    spin_lock(&info->lock);
1131
1132    if (!info->node_cache && new_leaf) {
1133        /* Save our speculative allocation into the cache */
1134        INIT_LIST_HEAD(&new_leaf->msg_list);
1135        info->node_cache = new_leaf;
1136        info->qsize += sizeof(*new_leaf);
1137    } else {
1138        kfree(new_leaf);
1139    }
1140
1141    if (info->attr.mq_curmsgs == 0) {
1142        if (f.file->f_flags & O_NONBLOCK) {
1143            spin_unlock(&info->lock);
1144            ret = -EAGAIN;
1145        } else {
1146            wait.task = current;
1147            wait.state = STATE_NONE;
1148            ret = wq_sleep(info, RECV, timeout, &wait);
1149            msg_ptr = wait.msg;
1150        }
1151    } else {
1152        msg_ptr = msg_get(info);
1153
1154        inode->i_atime = inode->i_mtime = inode->i_ctime =
1155                CURRENT_TIME;
1156
1157        /* There is now free space in queue. */
1158        pipelined_receive(info);
1159        spin_unlock(&info->lock);
1160        ret = 0;
1161    }
1162    if (ret == 0) {
1163        ret = msg_ptr->m_ts;
1164
1165        if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1166            store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1167            ret = -EFAULT;
1168        }
1169        free_msg(msg_ptr);
1170    }
1171out_fput:
1172    fdput(f);
1173out:
1174    return ret;
1175}
1176
1177/*
1178 * Notes: the case when user wants us to deregister (with NULL as pointer)
1179 * and he isn't currently owner of notification, will be silently discarded.
1180 * It isn't explicitly defined in the POSIX.
1181 */
1182SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1183        const struct sigevent __user *, u_notification)
1184{
1185    int ret;
1186    struct fd f;
1187    struct sock *sock;
1188    struct inode *inode;
1189    struct sigevent notification;
1190    struct mqueue_inode_info *info;
1191    struct sk_buff *nc;
1192
1193    if (u_notification) {
1194        if (copy_from_user(&notification, u_notification,
1195                    sizeof(struct sigevent)))
1196            return -EFAULT;
1197    }
1198
1199    audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1200
1201    nc = NULL;
1202    sock = NULL;
1203    if (u_notification != NULL) {
1204        if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1205                 notification.sigev_notify != SIGEV_SIGNAL &&
1206                 notification.sigev_notify != SIGEV_THREAD))
1207            return -EINVAL;
1208        if (notification.sigev_notify == SIGEV_SIGNAL &&
1209            !valid_signal(notification.sigev_signo)) {
1210            return -EINVAL;
1211        }
1212        if (notification.sigev_notify == SIGEV_THREAD) {
1213            long timeo;
1214
1215            /* create the notify skb */
1216            nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1217            if (!nc) {
1218                ret = -ENOMEM;
1219                goto out;
1220            }
1221            if (copy_from_user(nc->data,
1222                    notification.sigev_value.sival_ptr,
1223                    NOTIFY_COOKIE_LEN)) {
1224                ret = -EFAULT;
1225                goto out;
1226            }
1227
1228            /* TODO: add a header? */
1229            skb_put(nc, NOTIFY_COOKIE_LEN);
1230            /* and attach it to the socket */
1231retry:
1232            f = fdget(notification.sigev_signo);
1233            if (!f.file) {
1234                ret = -EBADF;
1235                goto out;
1236            }
1237            sock = netlink_getsockbyfilp(f.file);
1238            fdput(f);
1239            if (IS_ERR(sock)) {
1240                ret = PTR_ERR(sock);
1241                sock = NULL;
1242                goto out;
1243            }
1244
1245            timeo = MAX_SCHEDULE_TIMEOUT;
1246            ret = netlink_attachskb(sock, nc, &timeo, NULL);
1247            if (ret == 1)
1248                goto retry;
1249            if (ret) {
1250                sock = NULL;
1251                nc = NULL;
1252                goto out;
1253            }
1254        }
1255    }
1256
1257    f = fdget(mqdes);
1258    if (!f.file) {
1259        ret = -EBADF;
1260        goto out;
1261    }
1262
1263    inode = file_inode(f.file);
1264    if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1265        ret = -EBADF;
1266        goto out_fput;
1267    }
1268    info = MQUEUE_I(inode);
1269
1270    ret = 0;
1271    spin_lock(&info->lock);
1272    if (u_notification == NULL) {
1273        if (info->notify_owner == task_tgid(current)) {
1274            remove_notification(info);
1275            inode->i_atime = inode->i_ctime = CURRENT_TIME;
1276        }
1277    } else if (info->notify_owner != NULL) {
1278        ret = -EBUSY;
1279    } else {
1280        switch (notification.sigev_notify) {
1281        case SIGEV_NONE:
1282            info->notify.sigev_notify = SIGEV_NONE;
1283            break;
1284        case SIGEV_THREAD:
1285            info->notify_sock = sock;
1286            info->notify_cookie = nc;
1287            sock = NULL;
1288            nc = NULL;
1289            info->notify.sigev_notify = SIGEV_THREAD;
1290            break;
1291        case SIGEV_SIGNAL:
1292            info->notify.sigev_signo = notification.sigev_signo;
1293            info->notify.sigev_value = notification.sigev_value;
1294            info->notify.sigev_notify = SIGEV_SIGNAL;
1295            break;
1296        }
1297
1298        info->notify_owner = get_pid(task_tgid(current));
1299        info->notify_user_ns = get_user_ns(current_user_ns());
1300        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1301    }
1302    spin_unlock(&info->lock);
1303out_fput:
1304    fdput(f);
1305out:
1306    if (sock)
1307        netlink_detachskb(sock, nc);
1308    else if (nc)
1309        dev_kfree_skb(nc);
1310
1311    return ret;
1312}
1313
1314SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1315        const struct mq_attr __user *, u_mqstat,
1316        struct mq_attr __user *, u_omqstat)
1317{
1318    int ret;
1319    struct mq_attr mqstat, omqstat;
1320    struct fd f;
1321    struct inode *inode;
1322    struct mqueue_inode_info *info;
1323
1324    if (u_mqstat != NULL) {
1325        if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1326            return -EFAULT;
1327        if (mqstat.mq_flags & (~O_NONBLOCK))
1328            return -EINVAL;
1329    }
1330
1331    f = fdget(mqdes);
1332    if (!f.file) {
1333        ret = -EBADF;
1334        goto out;
1335    }
1336
1337    inode = file_inode(f.file);
1338    if (unlikely(f.file->f_op != &mqueue_file_operations)) {
1339        ret = -EBADF;
1340        goto out_fput;
1341    }
1342    info = MQUEUE_I(inode);
1343
1344    spin_lock(&info->lock);
1345
1346    omqstat = info->attr;
1347    omqstat.mq_flags = f.file->f_flags & O_NONBLOCK;
1348    if (u_mqstat) {
1349        audit_mq_getsetattr(mqdes, &mqstat);
1350        spin_lock(&f.file->f_lock);
1351        if (mqstat.mq_flags & O_NONBLOCK)
1352            f.file->f_flags |= O_NONBLOCK;
1353        else
1354            f.file->f_flags &= ~O_NONBLOCK;
1355        spin_unlock(&f.file->f_lock);
1356
1357        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1358    }
1359
1360    spin_unlock(&info->lock);
1361
1362    ret = 0;
1363    if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1364                        sizeof(struct mq_attr)))
1365        ret = -EFAULT;
1366
1367out_fput:
1368    fdput(f);
1369out:
1370    return ret;
1371}
1372
1373static const struct inode_operations mqueue_dir_inode_operations = {
1374    .lookup = simple_lookup,
1375    .create = mqueue_create,
1376    .unlink = mqueue_unlink,
1377};
1378
1379static const struct file_operations mqueue_file_operations = {
1380    .flush = mqueue_flush_file,
1381    .poll = mqueue_poll_file,
1382    .read = mqueue_read_file,
1383    .llseek = default_llseek,
1384};
1385
1386static const struct super_operations mqueue_super_ops = {
1387    .alloc_inode = mqueue_alloc_inode,
1388    .destroy_inode = mqueue_destroy_inode,
1389    .evict_inode = mqueue_evict_inode,
1390    .statfs = simple_statfs,
1391};
1392
1393static struct file_system_type mqueue_fs_type = {
1394    .name = "mqueue",
1395    .mount = mqueue_mount,
1396    .kill_sb = kill_litter_super,
1397    .fs_flags = FS_USERNS_MOUNT,
1398};
1399
1400int mq_init_ns(struct ipc_namespace *ns)
1401{
1402    ns->mq_queues_count = 0;
1403    ns->mq_queues_max = DFLT_QUEUESMAX;
1404    ns->mq_msg_max = DFLT_MSGMAX;
1405    ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1406    ns->mq_msg_default = DFLT_MSG;
1407    ns->mq_msgsize_default = DFLT_MSGSIZE;
1408
1409    ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1410    if (IS_ERR(ns->mq_mnt)) {
1411        int err = PTR_ERR(ns->mq_mnt);
1412        ns->mq_mnt = NULL;
1413        return err;
1414    }
1415    return 0;
1416}
1417
1418void mq_clear_sbinfo(struct ipc_namespace *ns)
1419{
1420    ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1421}
1422
1423void mq_put_mnt(struct ipc_namespace *ns)
1424{
1425    kern_unmount(ns->mq_mnt);
1426}
1427
1428static int __init init_mqueue_fs(void)
1429{
1430    int error;
1431
1432    mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1433                sizeof(struct mqueue_inode_info), 0,
1434                SLAB_HWCACHE_ALIGN, init_once);
1435    if (mqueue_inode_cachep == NULL)
1436        return -ENOMEM;
1437
1438    /* ignore failures - they are not fatal */
1439    mq_sysctl_table = mq_register_sysctl_table();
1440
1441    error = register_filesystem(&mqueue_fs_type);
1442    if (error)
1443        goto out_sysctl;
1444
1445    spin_lock_init(&mq_lock);
1446
1447    error = mq_init_ns(&init_ipc_ns);
1448    if (error)
1449        goto out_filesystem;
1450
1451    return 0;
1452
1453out_filesystem:
1454    unregister_filesystem(&mqueue_fs_type);
1455out_sysctl:
1456    if (mq_sysctl_table)
1457        unregister_sysctl_table(mq_sysctl_table);
1458    kmem_cache_destroy(mqueue_inode_cachep);
1459    return error;
1460}
1461
1462device_initcall(init_mqueue_fs);
1463

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