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

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