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_mode = mode;
120        inode->i_uid = current_fsuid();
121        inode->i_gid = current_fsgid();
122        inode->i_mtime = inode->i_ctime = inode->i_atime =
123                CURRENT_TIME;
124
125        if (S_ISREG(mode)) {
126            struct mqueue_inode_info *info;
127            struct task_struct *p = current;
128            unsigned long mq_bytes, mq_msg_tblsz;
129
130            inode->i_fop = &mqueue_file_operations;
131            inode->i_size = FILENT_SIZE;
132            /* mqueue specific info */
133            info = MQUEUE_I(inode);
134            spin_lock_init(&info->lock);
135            init_waitqueue_head(&info->wait_q);
136            INIT_LIST_HEAD(&info->e_wait_q[0].list);
137            INIT_LIST_HEAD(&info->e_wait_q[1].list);
138            info->notify_owner = NULL;
139            info->qsize = 0;
140            info->user = NULL; /* set when all is ok */
141            memset(&info->attr, 0, sizeof(info->attr));
142            info->attr.mq_maxmsg = ipc_ns->mq_msg_max;
143            info->attr.mq_msgsize = ipc_ns->mq_msgsize_max;
144            if (attr) {
145                info->attr.mq_maxmsg = attr->mq_maxmsg;
146                info->attr.mq_msgsize = attr->mq_msgsize;
147            }
148            mq_msg_tblsz = info->attr.mq_maxmsg * sizeof(struct msg_msg *);
149            info->messages = kmalloc(mq_msg_tblsz, GFP_KERNEL);
150            if (!info->messages)
151                goto out_inode;
152
153            mq_bytes = (mq_msg_tblsz +
154                (info->attr.mq_maxmsg * info->attr.mq_msgsize));
155
156            spin_lock(&mq_lock);
157            if (u->mq_bytes + mq_bytes < u->mq_bytes ||
158                 u->mq_bytes + mq_bytes >
159                task_rlimit(p, RLIMIT_MSGQUEUE)) {
160                spin_unlock(&mq_lock);
161                /* mqueue_delete_inode() releases info->messages */
162                goto out_inode;
163            }
164            u->mq_bytes += mq_bytes;
165            spin_unlock(&mq_lock);
166
167            /* all is ok */
168            info->user = get_uid(u);
169        } else if (S_ISDIR(mode)) {
170            inc_nlink(inode);
171            /* Some things misbehave if size == 0 on a directory */
172            inode->i_size = 2 * DIRENT_SIZE;
173            inode->i_op = &mqueue_dir_inode_operations;
174            inode->i_fop = &simple_dir_operations;
175        }
176    }
177    return inode;
178out_inode:
179    make_bad_inode(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 int mqueue_get_sb(struct file_system_type *fs_type,
215             int flags, const char *dev_name,
216             void *data, struct vfsmount *mnt)
217{
218    if (!(flags & MS_KERNMOUNT))
219        data = current->nsproxy->ipc_ns;
220    return get_sb_ns(fs_type, flags, data, mqueue_fill_super, mnt);
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_delete_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    if (S_ISDIR(inode->i_mode)) {
254        clear_inode(inode);
255        return;
256    }
257    ipc_ns = get_ns_from_inode(inode);
258    info = MQUEUE_I(inode);
259    spin_lock(&info->lock);
260    for (i = 0; i < info->attr.mq_curmsgs; i++)
261        free_msg(info->messages[i]);
262    kfree(info->messages);
263    spin_unlock(&info->lock);
264
265    clear_inode(inode);
266
267    /* Total amount of bytes accounted for the mqueue */
268    mq_bytes = info->attr.mq_maxmsg * (sizeof(struct msg_msg *)
269        + info->attr.mq_msgsize);
270    user = info->user;
271    if (user) {
272        spin_lock(&mq_lock);
273        user->mq_bytes -= mq_bytes;
274        /*
275         * get_ns_from_inode() ensures that the
276         * (ipc_ns = sb->s_fs_info) is either a valid ipc_ns
277         * to which we now hold a reference, or it is NULL.
278         * We can't put it here under mq_lock, though.
279         */
280        if (ipc_ns)
281            ipc_ns->mq_queues_count--;
282        spin_unlock(&mq_lock);
283        free_uid(user);
284    }
285    if (ipc_ns)
286        put_ipc_ns(ipc_ns);
287}
288
289static int mqueue_create(struct inode *dir, struct dentry *dentry,
290                int mode, struct nameidata *nd)
291{
292    struct inode *inode;
293    struct mq_attr *attr = dentry->d_fsdata;
294    int error;
295    struct ipc_namespace *ipc_ns;
296
297    spin_lock(&mq_lock);
298    ipc_ns = __get_ns_from_inode(dir);
299    if (!ipc_ns) {
300        error = -EACCES;
301        goto out_unlock;
302    }
303    if (ipc_ns->mq_queues_count >= ipc_ns->mq_queues_max &&
304            !capable(CAP_SYS_RESOURCE)) {
305        error = -ENOSPC;
306        goto out_unlock;
307    }
308    ipc_ns->mq_queues_count++;
309    spin_unlock(&mq_lock);
310
311    inode = mqueue_get_inode(dir->i_sb, ipc_ns, mode, attr);
312    if (!inode) {
313        error = -ENOMEM;
314        spin_lock(&mq_lock);
315        ipc_ns->mq_queues_count--;
316        goto out_unlock;
317    }
318
319    put_ipc_ns(ipc_ns);
320    dir->i_size += DIRENT_SIZE;
321    dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
322
323    d_instantiate(dentry, inode);
324    dget(dentry);
325    return 0;
326out_unlock:
327    spin_unlock(&mq_lock);
328    if (ipc_ns)
329        put_ipc_ns(ipc_ns);
330    return error;
331}
332
333static int mqueue_unlink(struct inode *dir, struct dentry *dentry)
334{
335      struct inode *inode = dentry->d_inode;
336
337    dir->i_ctime = dir->i_mtime = dir->i_atime = CURRENT_TIME;
338    dir->i_size -= DIRENT_SIZE;
339      drop_nlink(inode);
340      dput(dentry);
341      return 0;
342}
343
344/*
345* This is routine for system read from queue file.
346* To avoid mess with doing here some sort of mq_receive we allow
347* to read only queue size & notification info (the only values
348* that are interesting from user point of view and aren't accessible
349* through std routines)
350*/
351static ssize_t mqueue_read_file(struct file *filp, char __user *u_data,
352                size_t count, loff_t *off)
353{
354    struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
355    char buffer[FILENT_SIZE];
356    ssize_t ret;
357
358    spin_lock(&info->lock);
359    snprintf(buffer, sizeof(buffer),
360            "QSIZE:%-10lu NOTIFY:%-5d SIGNO:%-5d NOTIFY_PID:%-6d\n",
361            info->qsize,
362            info->notify_owner ? info->notify.sigev_notify : 0,
363            (info->notify_owner &&
364             info->notify.sigev_notify == SIGEV_SIGNAL) ?
365                info->notify.sigev_signo : 0,
366            pid_vnr(info->notify_owner));
367    spin_unlock(&info->lock);
368    buffer[sizeof(buffer)-1] = '\0';
369
370    ret = simple_read_from_buffer(u_data, count, off, buffer,
371                strlen(buffer));
372    if (ret <= 0)
373        return ret;
374
375    filp->f_path.dentry->d_inode->i_atime = filp->f_path.dentry->d_inode->i_ctime = CURRENT_TIME;
376    return ret;
377}
378
379static int mqueue_flush_file(struct file *filp, fl_owner_t id)
380{
381    struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
382
383    spin_lock(&info->lock);
384    if (task_tgid(current) == info->notify_owner)
385        remove_notification(info);
386
387    spin_unlock(&info->lock);
388    return 0;
389}
390
391static unsigned int mqueue_poll_file(struct file *filp, struct poll_table_struct *poll_tab)
392{
393    struct mqueue_inode_info *info = MQUEUE_I(filp->f_path.dentry->d_inode);
394    int retval = 0;
395
396    poll_wait(filp, &info->wait_q, poll_tab);
397
398    spin_lock(&info->lock);
399    if (info->attr.mq_curmsgs)
400        retval = POLLIN | POLLRDNORM;
401
402    if (info->attr.mq_curmsgs < info->attr.mq_maxmsg)
403        retval |= POLLOUT | POLLWRNORM;
404    spin_unlock(&info->lock);
405
406    return retval;
407}
408
409/* Adds current to info->e_wait_q[sr] before element with smaller prio */
410static void wq_add(struct mqueue_inode_info *info, int sr,
411            struct ext_wait_queue *ewp)
412{
413    struct ext_wait_queue *walk;
414
415    ewp->task = current;
416
417    list_for_each_entry(walk, &info->e_wait_q[sr].list, list) {
418        if (walk->task->static_prio <= current->static_prio) {
419            list_add_tail(&ewp->list, &walk->list);
420            return;
421        }
422    }
423    list_add_tail(&ewp->list, &info->e_wait_q[sr].list);
424}
425
426/*
427 * Puts current task to sleep. Caller must hold queue lock. After return
428 * lock isn't held.
429 * sr: SEND or RECV
430 */
431static int wq_sleep(struct mqueue_inode_info *info, int sr,
432            long timeout, struct ext_wait_queue *ewp)
433{
434    int retval;
435    signed long time;
436
437    wq_add(info, sr, ewp);
438
439    for (;;) {
440        set_current_state(TASK_INTERRUPTIBLE);
441
442        spin_unlock(&info->lock);
443        time = schedule_timeout(timeout);
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 long prepare_timeout(struct timespec *p)
556{
557    struct timespec nowts;
558    long timeout;
559
560    if (p) {
561        if (unlikely(p->tv_nsec < 0 || p->tv_sec < 0
562            || p->tv_nsec >= NSEC_PER_SEC))
563            return -EINVAL;
564        nowts = CURRENT_TIME;
565        /* first subtract as jiffies can't be too big */
566        p->tv_sec -= nowts.tv_sec;
567        if (p->tv_nsec < nowts.tv_nsec) {
568            p->tv_nsec += NSEC_PER_SEC;
569            p->tv_sec--;
570        }
571        p->tv_nsec -= nowts.tv_nsec;
572        if (p->tv_sec < 0)
573            return 0;
574
575        timeout = timespec_to_jiffies(p) + 1;
576    } else
577        return MAX_SCHEDULE_TIMEOUT;
578
579    return timeout;
580}
581
582static void remove_notification(struct mqueue_inode_info *info)
583{
584    if (info->notify_owner != NULL &&
585        info->notify.sigev_notify == SIGEV_THREAD) {
586        set_cookie(info->notify_cookie, NOTIFY_REMOVED);
587        netlink_sendskb(info->notify_sock, info->notify_cookie);
588    }
589    put_pid(info->notify_owner);
590    info->notify_owner = NULL;
591}
592
593static int mq_attr_ok(struct ipc_namespace *ipc_ns, struct mq_attr *attr)
594{
595    if (attr->mq_maxmsg <= 0 || attr->mq_msgsize <= 0)
596        return 0;
597    if (capable(CAP_SYS_RESOURCE)) {
598        if (attr->mq_maxmsg > HARD_MSGMAX)
599            return 0;
600    } else {
601        if (attr->mq_maxmsg > ipc_ns->mq_msg_max ||
602                attr->mq_msgsize > ipc_ns->mq_msgsize_max)
603            return 0;
604    }
605    /* check for overflow */
606    if (attr->mq_msgsize > ULONG_MAX/attr->mq_maxmsg)
607        return 0;
608    if ((unsigned long)(attr->mq_maxmsg * (attr->mq_msgsize
609        + sizeof (struct msg_msg *))) <
610        (unsigned long)(attr->mq_maxmsg * attr->mq_msgsize))
611        return 0;
612    return 1;
613}
614
615/*
616 * Invoked when creating a new queue via sys_mq_open
617 */
618static struct file *do_create(struct ipc_namespace *ipc_ns, struct dentry *dir,
619            struct dentry *dentry, int oflag, mode_t mode,
620            struct mq_attr *attr)
621{
622    const struct cred *cred = current_cred();
623    struct file *result;
624    int ret;
625
626    if (attr) {
627        if (!mq_attr_ok(ipc_ns, attr)) {
628            ret = -EINVAL;
629            goto out;
630        }
631        /* store for use during create */
632        dentry->d_fsdata = attr;
633    }
634
635    mode &= ~current_umask();
636    ret = mnt_want_write(ipc_ns->mq_mnt);
637    if (ret)
638        goto out;
639    ret = vfs_create(dir->d_inode, dentry, mode, NULL);
640    dentry->d_fsdata = NULL;
641    if (ret)
642        goto out_drop_write;
643
644    result = dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
645    /*
646     * dentry_open() took a persistent mnt_want_write(),
647     * so we can now drop this one.
648     */
649    mnt_drop_write(ipc_ns->mq_mnt);
650    return result;
651
652out_drop_write:
653    mnt_drop_write(ipc_ns->mq_mnt);
654out:
655    dput(dentry);
656    mntput(ipc_ns->mq_mnt);
657    return ERR_PTR(ret);
658}
659
660/* Opens existing queue */
661static struct file *do_open(struct ipc_namespace *ipc_ns,
662                struct dentry *dentry, int oflag)
663{
664    int ret;
665    const struct cred *cred = current_cred();
666
667    static const int oflag2acc[O_ACCMODE] = { MAY_READ, MAY_WRITE,
668                          MAY_READ | MAY_WRITE };
669
670    if ((oflag & O_ACCMODE) == (O_RDWR | O_WRONLY)) {
671        ret = -EINVAL;
672        goto err;
673    }
674
675    if (inode_permission(dentry->d_inode, oflag2acc[oflag & O_ACCMODE])) {
676        ret = -EACCES;
677        goto err;
678    }
679
680    return dentry_open(dentry, ipc_ns->mq_mnt, oflag, cred);
681
682err:
683    dput(dentry);
684    mntput(ipc_ns->mq_mnt);
685    return ERR_PTR(ret);
686}
687
688SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, mode_t, mode,
689        struct mq_attr __user *, u_attr)
690{
691    struct dentry *dentry;
692    struct file *filp;
693    char *name;
694    struct mq_attr attr;
695    int fd, error;
696    struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
697
698    if (u_attr && copy_from_user(&attr, u_attr, sizeof(struct mq_attr)))
699        return -EFAULT;
700
701    audit_mq_open(oflag, mode, u_attr ? &attr : NULL);
702
703    if (IS_ERR(name = getname(u_name)))
704        return PTR_ERR(name);
705
706    fd = get_unused_fd_flags(O_CLOEXEC);
707    if (fd < 0)
708        goto out_putname;
709
710    mutex_lock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
711    dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
712    if (IS_ERR(dentry)) {
713        error = PTR_ERR(dentry);
714        goto out_putfd;
715    }
716    mntget(ipc_ns->mq_mnt);
717
718    if (oflag & O_CREAT) {
719        if (dentry->d_inode) { /* entry already exists */
720            audit_inode(name, dentry);
721            if (oflag & O_EXCL) {
722                error = -EEXIST;
723                goto out;
724            }
725            filp = do_open(ipc_ns, dentry, oflag);
726        } else {
727            filp = do_create(ipc_ns, ipc_ns->mq_mnt->mnt_root,
728                        dentry, oflag, mode,
729                        u_attr ? &attr : NULL);
730        }
731    } else {
732        if (!dentry->d_inode) {
733            error = -ENOENT;
734            goto out;
735        }
736        audit_inode(name, dentry);
737        filp = do_open(ipc_ns, dentry, oflag);
738    }
739
740    if (IS_ERR(filp)) {
741        error = PTR_ERR(filp);
742        goto out_putfd;
743    }
744
745    fd_install(fd, filp);
746    goto out_upsem;
747
748out:
749    dput(dentry);
750    mntput(ipc_ns->mq_mnt);
751out_putfd:
752    put_unused_fd(fd);
753    fd = error;
754out_upsem:
755    mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
756out_putname:
757    putname(name);
758    return fd;
759}
760
761SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
762{
763    int err;
764    char *name;
765    struct dentry *dentry;
766    struct inode *inode = NULL;
767    struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
768
769    name = getname(u_name);
770    if (IS_ERR(name))
771        return PTR_ERR(name);
772
773    mutex_lock_nested(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex,
774            I_MUTEX_PARENT);
775    dentry = lookup_one_len(name, ipc_ns->mq_mnt->mnt_root, strlen(name));
776    if (IS_ERR(dentry)) {
777        err = PTR_ERR(dentry);
778        goto out_unlock;
779    }
780
781    if (!dentry->d_inode) {
782        err = -ENOENT;
783        goto out_err;
784    }
785
786    inode = dentry->d_inode;
787    if (inode)
788        atomic_inc(&inode->i_count);
789    err = mnt_want_write(ipc_ns->mq_mnt);
790    if (err)
791        goto out_err;
792    err = vfs_unlink(dentry->d_parent->d_inode, dentry);
793    mnt_drop_write(ipc_ns->mq_mnt);
794out_err:
795    dput(dentry);
796
797out_unlock:
798    mutex_unlock(&ipc_ns->mq_mnt->mnt_root->d_inode->i_mutex);
799    putname(name);
800    if (inode)
801        iput(inode);
802
803    return err;
804}
805
806/* Pipelined send and receive functions.
807 *
808 * If a receiver finds no waiting message, then it registers itself in the
809 * list of waiting receivers. A sender checks that list before adding the new
810 * message into the message array. If there is a waiting receiver, then it
811 * bypasses the message array and directly hands the message over to the
812 * receiver.
813 * The receiver accepts the message and returns without grabbing the queue
814 * spinlock. Therefore an intermediate STATE_PENDING state and memory barriers
815 * are necessary. The same algorithm is used for sysv semaphores, see
816 * ipc/sem.c for more details.
817 *
818 * The same algorithm is used for senders.
819 */
820
821/* pipelined_send() - send a message directly to the task waiting in
822 * sys_mq_timedreceive() (without inserting message into a queue).
823 */
824static inline void pipelined_send(struct mqueue_inode_info *info,
825                  struct msg_msg *message,
826                  struct ext_wait_queue *receiver)
827{
828    receiver->msg = message;
829    list_del(&receiver->list);
830    receiver->state = STATE_PENDING;
831    wake_up_process(receiver->task);
832    smp_wmb();
833    receiver->state = STATE_READY;
834}
835
836/* pipelined_receive() - if there is task waiting in sys_mq_timedsend()
837 * gets its message and put to the queue (we have one free place for sure). */
838static inline void pipelined_receive(struct mqueue_inode_info *info)
839{
840    struct ext_wait_queue *sender = wq_get_first_waiter(info, SEND);
841
842    if (!sender) {
843        /* for poll */
844        wake_up_interruptible(&info->wait_q);
845        return;
846    }
847    msg_insert(sender->msg, info);
848    list_del(&sender->list);
849    sender->state = STATE_PENDING;
850    wake_up_process(sender->task);
851    smp_wmb();
852    sender->state = STATE_READY;
853}
854
855SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
856        size_t, msg_len, unsigned int, msg_prio,
857        const struct timespec __user *, u_abs_timeout)
858{
859    struct file *filp;
860    struct inode *inode;
861    struct ext_wait_queue wait;
862    struct ext_wait_queue *receiver;
863    struct msg_msg *msg_ptr;
864    struct mqueue_inode_info *info;
865    struct timespec ts, *p = NULL;
866    long timeout;
867    int ret;
868
869    if (u_abs_timeout) {
870        if (copy_from_user(&ts, u_abs_timeout,
871                    sizeof(struct timespec)))
872            return -EFAULT;
873        p = &ts;
874    }
875
876    if (unlikely(msg_prio >= (unsigned long) MQ_PRIO_MAX))
877        return -EINVAL;
878
879    audit_mq_sendrecv(mqdes, msg_len, msg_prio, p);
880    timeout = prepare_timeout(p);
881
882    filp = fget(mqdes);
883    if (unlikely(!filp)) {
884        ret = -EBADF;
885        goto out;
886    }
887
888    inode = filp->f_path.dentry->d_inode;
889    if (unlikely(filp->f_op != &mqueue_file_operations)) {
890        ret = -EBADF;
891        goto out_fput;
892    }
893    info = MQUEUE_I(inode);
894    audit_inode(NULL, filp->f_path.dentry);
895
896    if (unlikely(!(filp->f_mode & FMODE_WRITE))) {
897        ret = -EBADF;
898        goto out_fput;
899    }
900
901    if (unlikely(msg_len > info->attr.mq_msgsize)) {
902        ret = -EMSGSIZE;
903        goto out_fput;
904    }
905
906    /* First try to allocate memory, before doing anything with
907     * existing queues. */
908    msg_ptr = load_msg(u_msg_ptr, msg_len);
909    if (IS_ERR(msg_ptr)) {
910        ret = PTR_ERR(msg_ptr);
911        goto out_fput;
912    }
913    msg_ptr->m_ts = msg_len;
914    msg_ptr->m_type = msg_prio;
915
916    spin_lock(&info->lock);
917
918    if (info->attr.mq_curmsgs == info->attr.mq_maxmsg) {
919        if (filp->f_flags & O_NONBLOCK) {
920            spin_unlock(&info->lock);
921            ret = -EAGAIN;
922        } else if (unlikely(timeout < 0)) {
923            spin_unlock(&info->lock);
924            ret = timeout;
925        } else {
926            wait.task = current;
927            wait.msg = (void *) msg_ptr;
928            wait.state = STATE_NONE;
929            ret = wq_sleep(info, SEND, timeout, &wait);
930        }
931        if (ret < 0)
932            free_msg(msg_ptr);
933    } else {
934        receiver = wq_get_first_waiter(info, RECV);
935        if (receiver) {
936            pipelined_send(info, msg_ptr, receiver);
937        } else {
938            /* adds message to the queue */
939            msg_insert(msg_ptr, info);
940            __do_notify(info);
941        }
942        inode->i_atime = inode->i_mtime = inode->i_ctime =
943                CURRENT_TIME;
944        spin_unlock(&info->lock);
945        ret = 0;
946    }
947out_fput:
948    fput(filp);
949out:
950    return ret;
951}
952
953SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
954        size_t, msg_len, unsigned int __user *, u_msg_prio,
955        const struct timespec __user *, u_abs_timeout)
956{
957    long timeout;
958    ssize_t ret;
959    struct msg_msg *msg_ptr;
960    struct file *filp;
961    struct inode *inode;
962    struct mqueue_inode_info *info;
963    struct ext_wait_queue wait;
964    struct timespec ts, *p = NULL;
965
966    if (u_abs_timeout) {
967        if (copy_from_user(&ts, u_abs_timeout,
968                    sizeof(struct timespec)))
969            return -EFAULT;
970        p = &ts;
971    }
972
973    audit_mq_sendrecv(mqdes, msg_len, 0, p);
974    timeout = prepare_timeout(p);
975
976    filp = fget(mqdes);
977    if (unlikely(!filp)) {
978        ret = -EBADF;
979        goto out;
980    }
981
982    inode = filp->f_path.dentry->d_inode;
983    if (unlikely(filp->f_op != &mqueue_file_operations)) {
984        ret = -EBADF;
985        goto out_fput;
986    }
987    info = MQUEUE_I(inode);
988    audit_inode(NULL, filp->f_path.dentry);
989
990    if (unlikely(!(filp->f_mode & FMODE_READ))) {
991        ret = -EBADF;
992        goto out_fput;
993    }
994
995    /* checks if buffer is big enough */
996    if (unlikely(msg_len < info->attr.mq_msgsize)) {
997        ret = -EMSGSIZE;
998        goto out_fput;
999    }
1000
1001    spin_lock(&info->lock);
1002    if (info->attr.mq_curmsgs == 0) {
1003        if (filp->f_flags & O_NONBLOCK) {
1004            spin_unlock(&info->lock);
1005            ret = -EAGAIN;
1006            msg_ptr = NULL;
1007        } else if (unlikely(timeout < 0)) {
1008            spin_unlock(&info->lock);
1009            ret = timeout;
1010            msg_ptr = NULL;
1011        } else {
1012            wait.task = current;
1013            wait.state = STATE_NONE;
1014            ret = wq_sleep(info, RECV, timeout, &wait);
1015            msg_ptr = wait.msg;
1016        }
1017    } else {
1018        msg_ptr = msg_get(info);
1019
1020        inode->i_atime = inode->i_mtime = inode->i_ctime =
1021                CURRENT_TIME;
1022
1023        /* There is now free space in queue. */
1024        pipelined_receive(info);
1025        spin_unlock(&info->lock);
1026        ret = 0;
1027    }
1028    if (ret == 0) {
1029        ret = msg_ptr->m_ts;
1030
1031        if ((u_msg_prio && put_user(msg_ptr->m_type, u_msg_prio)) ||
1032            store_msg(u_msg_ptr, msg_ptr, msg_ptr->m_ts)) {
1033            ret = -EFAULT;
1034        }
1035        free_msg(msg_ptr);
1036    }
1037out_fput:
1038    fput(filp);
1039out:
1040    return ret;
1041}
1042
1043/*
1044 * Notes: the case when user wants us to deregister (with NULL as pointer)
1045 * and he isn't currently owner of notification, will be silently discarded.
1046 * It isn't explicitly defined in the POSIX.
1047 */
1048SYSCALL_DEFINE2(mq_notify, mqd_t, mqdes,
1049        const struct sigevent __user *, u_notification)
1050{
1051    int ret;
1052    struct file *filp;
1053    struct sock *sock;
1054    struct inode *inode;
1055    struct sigevent notification;
1056    struct mqueue_inode_info *info;
1057    struct sk_buff *nc;
1058
1059    if (u_notification) {
1060        if (copy_from_user(&notification, u_notification,
1061                    sizeof(struct sigevent)))
1062            return -EFAULT;
1063    }
1064
1065    audit_mq_notify(mqdes, u_notification ? &notification : NULL);
1066
1067    nc = NULL;
1068    sock = NULL;
1069    if (u_notification != NULL) {
1070        if (unlikely(notification.sigev_notify != SIGEV_NONE &&
1071                 notification.sigev_notify != SIGEV_SIGNAL &&
1072                 notification.sigev_notify != SIGEV_THREAD))
1073            return -EINVAL;
1074        if (notification.sigev_notify == SIGEV_SIGNAL &&
1075            !valid_signal(notification.sigev_signo)) {
1076            return -EINVAL;
1077        }
1078        if (notification.sigev_notify == SIGEV_THREAD) {
1079            long timeo;
1080
1081            /* create the notify skb */
1082            nc = alloc_skb(NOTIFY_COOKIE_LEN, GFP_KERNEL);
1083            if (!nc) {
1084                ret = -ENOMEM;
1085                goto out;
1086            }
1087            if (copy_from_user(nc->data,
1088                    notification.sigev_value.sival_ptr,
1089                    NOTIFY_COOKIE_LEN)) {
1090                ret = -EFAULT;
1091                goto out;
1092            }
1093
1094            /* TODO: add a header? */
1095            skb_put(nc, NOTIFY_COOKIE_LEN);
1096            /* and attach it to the socket */
1097retry:
1098            filp = fget(notification.sigev_signo);
1099            if (!filp) {
1100                ret = -EBADF;
1101                goto out;
1102            }
1103            sock = netlink_getsockbyfilp(filp);
1104            fput(filp);
1105            if (IS_ERR(sock)) {
1106                ret = PTR_ERR(sock);
1107                sock = NULL;
1108                goto out;
1109            }
1110
1111            timeo = MAX_SCHEDULE_TIMEOUT;
1112            ret = netlink_attachskb(sock, nc, &timeo, NULL);
1113            if (ret == 1)
1114                goto retry;
1115            if (ret) {
1116                sock = NULL;
1117                nc = NULL;
1118                goto out;
1119            }
1120        }
1121    }
1122
1123    filp = fget(mqdes);
1124    if (!filp) {
1125        ret = -EBADF;
1126        goto out;
1127    }
1128
1129    inode = filp->f_path.dentry->d_inode;
1130    if (unlikely(filp->f_op != &mqueue_file_operations)) {
1131        ret = -EBADF;
1132        goto out_fput;
1133    }
1134    info = MQUEUE_I(inode);
1135
1136    ret = 0;
1137    spin_lock(&info->lock);
1138    if (u_notification == NULL) {
1139        if (info->notify_owner == task_tgid(current)) {
1140            remove_notification(info);
1141            inode->i_atime = inode->i_ctime = CURRENT_TIME;
1142        }
1143    } else if (info->notify_owner != NULL) {
1144        ret = -EBUSY;
1145    } else {
1146        switch (notification.sigev_notify) {
1147        case SIGEV_NONE:
1148            info->notify.sigev_notify = SIGEV_NONE;
1149            break;
1150        case SIGEV_THREAD:
1151            info->notify_sock = sock;
1152            info->notify_cookie = nc;
1153            sock = NULL;
1154            nc = NULL;
1155            info->notify.sigev_notify = SIGEV_THREAD;
1156            break;
1157        case SIGEV_SIGNAL:
1158            info->notify.sigev_signo = notification.sigev_signo;
1159            info->notify.sigev_value = notification.sigev_value;
1160            info->notify.sigev_notify = SIGEV_SIGNAL;
1161            break;
1162        }
1163
1164        info->notify_owner = get_pid(task_tgid(current));
1165        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1166    }
1167    spin_unlock(&info->lock);
1168out_fput:
1169    fput(filp);
1170out:
1171    if (sock) {
1172        netlink_detachskb(sock, nc);
1173    } else if (nc) {
1174        dev_kfree_skb(nc);
1175    }
1176    return ret;
1177}
1178
1179SYSCALL_DEFINE3(mq_getsetattr, mqd_t, mqdes,
1180        const struct mq_attr __user *, u_mqstat,
1181        struct mq_attr __user *, u_omqstat)
1182{
1183    int ret;
1184    struct mq_attr mqstat, omqstat;
1185    struct file *filp;
1186    struct inode *inode;
1187    struct mqueue_inode_info *info;
1188
1189    if (u_mqstat != NULL) {
1190        if (copy_from_user(&mqstat, u_mqstat, sizeof(struct mq_attr)))
1191            return -EFAULT;
1192        if (mqstat.mq_flags & (~O_NONBLOCK))
1193            return -EINVAL;
1194    }
1195
1196    filp = fget(mqdes);
1197    if (!filp) {
1198        ret = -EBADF;
1199        goto out;
1200    }
1201
1202    inode = filp->f_path.dentry->d_inode;
1203    if (unlikely(filp->f_op != &mqueue_file_operations)) {
1204        ret = -EBADF;
1205        goto out_fput;
1206    }
1207    info = MQUEUE_I(inode);
1208
1209    spin_lock(&info->lock);
1210
1211    omqstat = info->attr;
1212    omqstat.mq_flags = filp->f_flags & O_NONBLOCK;
1213    if (u_mqstat) {
1214        audit_mq_getsetattr(mqdes, &mqstat);
1215        spin_lock(&filp->f_lock);
1216        if (mqstat.mq_flags & O_NONBLOCK)
1217            filp->f_flags |= O_NONBLOCK;
1218        else
1219            filp->f_flags &= ~O_NONBLOCK;
1220        spin_unlock(&filp->f_lock);
1221
1222        inode->i_atime = inode->i_ctime = CURRENT_TIME;
1223    }
1224
1225    spin_unlock(&info->lock);
1226
1227    ret = 0;
1228    if (u_omqstat != NULL && copy_to_user(u_omqstat, &omqstat,
1229                        sizeof(struct mq_attr)))
1230        ret = -EFAULT;
1231
1232out_fput:
1233    fput(filp);
1234out:
1235    return ret;
1236}
1237
1238static const struct inode_operations mqueue_dir_inode_operations = {
1239    .lookup = simple_lookup,
1240    .create = mqueue_create,
1241    .unlink = mqueue_unlink,
1242};
1243
1244static const struct file_operations mqueue_file_operations = {
1245    .flush = mqueue_flush_file,
1246    .poll = mqueue_poll_file,
1247    .read = mqueue_read_file,
1248};
1249
1250static const struct super_operations mqueue_super_ops = {
1251    .alloc_inode = mqueue_alloc_inode,
1252    .destroy_inode = mqueue_destroy_inode,
1253    .statfs = simple_statfs,
1254    .delete_inode = mqueue_delete_inode,
1255    .drop_inode = generic_delete_inode,
1256};
1257
1258static struct file_system_type mqueue_fs_type = {
1259    .name = "mqueue",
1260    .get_sb = mqueue_get_sb,
1261    .kill_sb = kill_litter_super,
1262};
1263
1264int mq_init_ns(struct ipc_namespace *ns)
1265{
1266    ns->mq_queues_count = 0;
1267    ns->mq_queues_max = DFLT_QUEUESMAX;
1268    ns->mq_msg_max = DFLT_MSGMAX;
1269    ns->mq_msgsize_max = DFLT_MSGSIZEMAX;
1270
1271    ns->mq_mnt = kern_mount_data(&mqueue_fs_type, ns);
1272    if (IS_ERR(ns->mq_mnt)) {
1273        int err = PTR_ERR(ns->mq_mnt);
1274        ns->mq_mnt = NULL;
1275        return err;
1276    }
1277    return 0;
1278}
1279
1280void mq_clear_sbinfo(struct ipc_namespace *ns)
1281{
1282    ns->mq_mnt->mnt_sb->s_fs_info = NULL;
1283}
1284
1285void mq_put_mnt(struct ipc_namespace *ns)
1286{
1287    mntput(ns->mq_mnt);
1288}
1289
1290static int __init init_mqueue_fs(void)
1291{
1292    int error;
1293
1294    mqueue_inode_cachep = kmem_cache_create("mqueue_inode_cache",
1295                sizeof(struct mqueue_inode_info), 0,
1296                SLAB_HWCACHE_ALIGN, init_once);
1297    if (mqueue_inode_cachep == NULL)
1298        return -ENOMEM;
1299
1300    /* ignore failures - they are not fatal */
1301    mq_sysctl_table = mq_register_sysctl_table();
1302
1303    error = register_filesystem(&mqueue_fs_type);
1304    if (error)
1305        goto out_sysctl;
1306
1307    spin_lock_init(&mq_lock);
1308
1309    init_ipc_ns.mq_mnt = kern_mount_data(&mqueue_fs_type, &init_ipc_ns);
1310    if (IS_ERR(init_ipc_ns.mq_mnt)) {
1311        error = PTR_ERR(init_ipc_ns.mq_mnt);
1312        goto out_filesystem;
1313    }
1314
1315    return 0;
1316
1317out_filesystem:
1318    unregister_filesystem(&mqueue_fs_type);
1319out_sysctl:
1320    if (mq_sysctl_table)
1321        unregister_sysctl_table(mq_sysctl_table);
1322    kmem_cache_destroy(mqueue_inode_cachep);
1323    return error;
1324}
1325
1326__initcall(init_mqueue_fs);
1327

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