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[/] [test_project/] [trunk/] [linux_sd_driver/] [ipc/] [util.c] - Blame information for rev 81

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1 62 marcus.erl
/*
2
 * linux/ipc/util.c
3
 * Copyright (C) 1992 Krishna Balasubramanian
4
 *
5
 * Sep 1997 - Call suser() last after "normal" permission checks so we
6
 *            get BSD style process accounting right.
7
 *            Occurs in several places in the IPC code.
8
 *            Chris Evans, <chris@ferret.lmh.ox.ac.uk>
9
 * Nov 1999 - ipc helper functions, unified SMP locking
10
 *            Manfred Spraul <manfred@colorfullife.com>
11
 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
12
 *            Mingming Cao <cmm@us.ibm.com>
13
 * Mar 2006 - support for audit of ipc object properties
14
 *            Dustin Kirkland <dustin.kirkland@us.ibm.com>
15
 * Jun 2006 - namespaces ssupport
16
 *            OpenVZ, SWsoft Inc.
17
 *            Pavel Emelianov <xemul@openvz.org>
18
 */
19
 
20
#include <linux/mm.h>
21
#include <linux/shm.h>
22
#include <linux/init.h>
23
#include <linux/msg.h>
24
#include <linux/vmalloc.h>
25
#include <linux/slab.h>
26
#include <linux/capability.h>
27
#include <linux/highuid.h>
28
#include <linux/security.h>
29
#include <linux/rcupdate.h>
30
#include <linux/workqueue.h>
31
#include <linux/seq_file.h>
32
#include <linux/proc_fs.h>
33
#include <linux/audit.h>
34
#include <linux/nsproxy.h>
35
#include <linux/rwsem.h>
36
 
37
#include <asm/unistd.h>
38
 
39
#include "util.h"
40
 
41
struct ipc_proc_iface {
42
        const char *path;
43
        const char *header;
44
        int ids;
45
        int (*show)(struct seq_file *, void *);
46
};
47
 
48
struct ipc_namespace init_ipc_ns = {
49
        .kref = {
50
                .refcount       = ATOMIC_INIT(2),
51
        },
52
};
53
 
54
static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
55
{
56
        int err;
57
        struct ipc_namespace *ns;
58
 
59
        err = -ENOMEM;
60
        ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
61
        if (ns == NULL)
62
                goto err_mem;
63
 
64
        err = sem_init_ns(ns);
65
        if (err)
66
                goto err_sem;
67
        err = msg_init_ns(ns);
68
        if (err)
69
                goto err_msg;
70
        err = shm_init_ns(ns);
71
        if (err)
72
                goto err_shm;
73
 
74
        kref_init(&ns->kref);
75
        return ns;
76
 
77
err_shm:
78
        msg_exit_ns(ns);
79
err_msg:
80
        sem_exit_ns(ns);
81
err_sem:
82
        kfree(ns);
83
err_mem:
84
        return ERR_PTR(err);
85
}
86
 
87
struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns)
88
{
89
        struct ipc_namespace *new_ns;
90
 
91
        BUG_ON(!ns);
92
        get_ipc_ns(ns);
93
 
94
        if (!(flags & CLONE_NEWIPC))
95
                return ns;
96
 
97
        new_ns = clone_ipc_ns(ns);
98
 
99
        put_ipc_ns(ns);
100
        return new_ns;
101
}
102
 
103
void free_ipc_ns(struct kref *kref)
104
{
105
        struct ipc_namespace *ns;
106
 
107
        ns = container_of(kref, struct ipc_namespace, kref);
108
        sem_exit_ns(ns);
109
        msg_exit_ns(ns);
110
        shm_exit_ns(ns);
111
        kfree(ns);
112
}
113
 
114
/**
115
 *      ipc_init        -       initialise IPC subsystem
116
 *
117
 *      The various system5 IPC resources (semaphores, messages and shared
118
 *      memory) are initialised
119
 */
120
 
121
static int __init ipc_init(void)
122
{
123
        sem_init();
124
        msg_init();
125
        shm_init();
126
        return 0;
127
}
128
__initcall(ipc_init);
129
 
130
/**
131
 *      ipc_init_ids            -       initialise IPC identifiers
132
 *      @ids: Identifier set
133
 *
134
 *      Set up the sequence range to use for the ipc identifier range (limited
135
 *      below IPCMNI) then initialise the ids idr.
136
 */
137
 
138
void ipc_init_ids(struct ipc_ids *ids)
139
{
140
        init_rwsem(&ids->rw_mutex);
141
 
142
        ids->in_use = 0;
143
        ids->seq = 0;
144
        {
145
                int seq_limit = INT_MAX/SEQ_MULTIPLIER;
146
                if(seq_limit > USHRT_MAX)
147
                        ids->seq_max = USHRT_MAX;
148
                 else
149
                        ids->seq_max = seq_limit;
150
        }
151
 
152
        idr_init(&ids->ipcs_idr);
153
}
154
 
155
#ifdef CONFIG_PROC_FS
156
static const struct file_operations sysvipc_proc_fops;
157
/**
158
 *      ipc_init_proc_interface -  Create a proc interface for sysipc types using a seq_file interface.
159
 *      @path: Path in procfs
160
 *      @header: Banner to be printed at the beginning of the file.
161
 *      @ids: ipc id table to iterate.
162
 *      @show: show routine.
163
 */
164
void __init ipc_init_proc_interface(const char *path, const char *header,
165
                int ids, int (*show)(struct seq_file *, void *))
166
{
167
        struct proc_dir_entry *pde;
168
        struct ipc_proc_iface *iface;
169
 
170
        iface = kmalloc(sizeof(*iface), GFP_KERNEL);
171
        if (!iface)
172
                return;
173
        iface->path     = path;
174
        iface->header   = header;
175
        iface->ids      = ids;
176
        iface->show     = show;
177
 
178
        pde = create_proc_entry(path,
179
                                S_IRUGO,        /* world readable */
180
                                NULL            /* parent dir */);
181
        if (pde) {
182
                pde->data = iface;
183
                pde->proc_fops = &sysvipc_proc_fops;
184
        } else {
185
                kfree(iface);
186
        }
187
}
188
#endif
189
 
190
/**
191
 *      ipc_findkey     -       find a key in an ipc identifier set
192
 *      @ids: Identifier set
193
 *      @key: The key to find
194
 *
195
 *      Requires ipc_ids.rw_mutex locked.
196
 *      Returns the LOCKED pointer to the ipc structure if found or NULL
197
 *      if not.
198
 *      If key is found ipc points to the owning ipc structure
199
 */
200
 
201
static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
202
{
203
        struct kern_ipc_perm *ipc;
204
        int next_id;
205
        int total;
206
 
207
        for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
208
                ipc = idr_find(&ids->ipcs_idr, next_id);
209
 
210
                if (ipc == NULL)
211
                        continue;
212
 
213
                if (ipc->key != key) {
214
                        total++;
215
                        continue;
216
                }
217
 
218
                ipc_lock_by_ptr(ipc);
219
                return ipc;
220
        }
221
 
222
        return NULL;
223
}
224
 
225
/**
226
 *      ipc_get_maxid   -       get the last assigned id
227
 *      @ids: IPC identifier set
228
 *
229
 *      Called with ipc_ids.rw_mutex held.
230
 */
231
 
232
int ipc_get_maxid(struct ipc_ids *ids)
233
{
234
        struct kern_ipc_perm *ipc;
235
        int max_id = -1;
236
        int total, id;
237
 
238
        if (ids->in_use == 0)
239
                return -1;
240
 
241
        if (ids->in_use == IPCMNI)
242
                return IPCMNI - 1;
243
 
244
        /* Look for the last assigned id */
245
        total = 0;
246
        for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
247
                ipc = idr_find(&ids->ipcs_idr, id);
248
                if (ipc != NULL) {
249
                        max_id = id;
250
                        total++;
251
                }
252
        }
253
        return max_id;
254
}
255
 
256
/**
257
 *      ipc_addid       -       add an IPC identifier
258
 *      @ids: IPC identifier set
259
 *      @new: new IPC permission set
260
 *      @size: limit for the number of used ids
261
 *
262
 *      Add an entry 'new' to the IPC ids idr. The permissions object is
263
 *      initialised and the first free entry is set up and the id assigned
264
 *      is returned. The 'new' entry is returned in a locked state on success.
265
 *      On failure the entry is not locked and a negative err-code is returned.
266
 *
267
 *      Called with ipc_ids.rw_mutex held as a writer.
268
 */
269
 
270
int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
271
{
272
        int id, err;
273
 
274
        if (size > IPCMNI)
275
                size = IPCMNI;
276
 
277
        if (ids->in_use >= size)
278
                return -ENOSPC;
279
 
280
        err = idr_get_new(&ids->ipcs_idr, new, &id);
281
        if (err)
282
                return err;
283
 
284
        ids->in_use++;
285
 
286
        new->cuid = new->uid = current->euid;
287
        new->gid = new->cgid = current->egid;
288
 
289
        new->seq = ids->seq++;
290
        if(ids->seq > ids->seq_max)
291
                ids->seq = 0;
292
 
293
        spin_lock_init(&new->lock);
294
        new->deleted = 0;
295
        rcu_read_lock();
296
        spin_lock(&new->lock);
297
        return id;
298
}
299
 
300
/**
301
 *      ipcget_new      -       create a new ipc object
302
 *      @ns: namespace
303
 *      @ids: IPC identifer set
304
 *      @ops: the actual creation routine to call
305
 *      @params: its parameters
306
 *
307
 *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
308
 *      when the key is IPC_PRIVATE.
309
 */
310
int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
311
                struct ipc_ops *ops, struct ipc_params *params)
312
{
313
        int err;
314
retry:
315
        err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
316
 
317
        if (!err)
318
                return -ENOMEM;
319
 
320
        down_write(&ids->rw_mutex);
321
        err = ops->getnew(ns, params);
322
        up_write(&ids->rw_mutex);
323
 
324
        if (err == -EAGAIN)
325
                goto retry;
326
 
327
        return err;
328
}
329
 
330
/**
331
 *      ipc_check_perms -       check security and permissions for an IPC
332
 *      @ipcp: ipc permission set
333
 *      @ops: the actual security routine to call
334
 *      @params: its parameters
335
 *
336
 *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
337
 *      when the key is not IPC_PRIVATE and that key already exists in the
338
 *      ids IDR.
339
 *
340
 *      On success, the IPC id is returned.
341
 *
342
 *      It is called with ipc_ids.rw_mutex and ipcp->lock held.
343
 */
344
static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
345
                        struct ipc_params *params)
346
{
347
        int err;
348
 
349
        if (ipcperms(ipcp, params->flg))
350
                err = -EACCES;
351
        else {
352
                err = ops->associate(ipcp, params->flg);
353
                if (!err)
354
                        err = ipcp->id;
355
        }
356
 
357
        return err;
358
}
359
 
360
/**
361
 *      ipcget_public   -       get an ipc object or create a new one
362
 *      @ns: namespace
363
 *      @ids: IPC identifer set
364
 *      @ops: the actual creation routine to call
365
 *      @params: its parameters
366
 *
367
 *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
368
 *      when the key is not IPC_PRIVATE.
369
 *      It adds a new entry if the key is not found and does some permission
370
 *      / security checkings if the key is found.
371
 *
372
 *      On success, the ipc id is returned.
373
 */
374
int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
375
                struct ipc_ops *ops, struct ipc_params *params)
376
{
377
        struct kern_ipc_perm *ipcp;
378
        int flg = params->flg;
379
        int err;
380
retry:
381
        err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
382
 
383
        /*
384
         * Take the lock as a writer since we are potentially going to add
385
         * a new entry + read locks are not "upgradable"
386
         */
387
        down_write(&ids->rw_mutex);
388
        ipcp = ipc_findkey(ids, params->key);
389
        if (ipcp == NULL) {
390
                /* key not used */
391
                if (!(flg & IPC_CREAT))
392
                        err = -ENOENT;
393
                else if (!err)
394
                        err = -ENOMEM;
395
                else
396
                        err = ops->getnew(ns, params);
397
        } else {
398
                /* ipc object has been locked by ipc_findkey() */
399
 
400
                if (flg & IPC_CREAT && flg & IPC_EXCL)
401
                        err = -EEXIST;
402
                else {
403
                        err = 0;
404
                        if (ops->more_checks)
405
                                err = ops->more_checks(ipcp, params);
406
                        if (!err)
407
                                /*
408
                                 * ipc_check_perms returns the IPC id on
409
                                 * success
410
                                 */
411
                                err = ipc_check_perms(ipcp, ops, params);
412
                }
413
                ipc_unlock(ipcp);
414
        }
415
        up_write(&ids->rw_mutex);
416
 
417
        if (err == -EAGAIN)
418
                goto retry;
419
 
420
        return err;
421
}
422
 
423
 
424
/**
425
 *      ipc_rmid        -       remove an IPC identifier
426
 *      @ids: IPC identifier set
427
 *      @ipcp: ipc perm structure containing the identifier to remove
428
 *
429
 *      ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
430
 *      before this function is called, and remain locked on the exit.
431
 */
432
 
433
void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
434
{
435
        int lid = ipcid_to_idx(ipcp->id);
436
 
437
        idr_remove(&ids->ipcs_idr, lid);
438
 
439
        ids->in_use--;
440
 
441
        ipcp->deleted = 1;
442
 
443
        return;
444
}
445
 
446
/**
447
 *      ipc_alloc       -       allocate ipc space
448
 *      @size: size desired
449
 *
450
 *      Allocate memory from the appropriate pools and return a pointer to it.
451
 *      NULL is returned if the allocation fails
452
 */
453
 
454
void* ipc_alloc(int size)
455
{
456
        void* out;
457
        if(size > PAGE_SIZE)
458
                out = vmalloc(size);
459
        else
460
                out = kmalloc(size, GFP_KERNEL);
461
        return out;
462
}
463
 
464
/**
465
 *      ipc_free        -       free ipc space
466
 *      @ptr: pointer returned by ipc_alloc
467
 *      @size: size of block
468
 *
469
 *      Free a block created with ipc_alloc(). The caller must know the size
470
 *      used in the allocation call.
471
 */
472
 
473
void ipc_free(void* ptr, int size)
474
{
475
        if(size > PAGE_SIZE)
476
                vfree(ptr);
477
        else
478
                kfree(ptr);
479
}
480
 
481
/*
482
 * rcu allocations:
483
 * There are three headers that are prepended to the actual allocation:
484
 * - during use: ipc_rcu_hdr.
485
 * - during the rcu grace period: ipc_rcu_grace.
486
 * - [only if vmalloc]: ipc_rcu_sched.
487
 * Their lifetime doesn't overlap, thus the headers share the same memory.
488
 * Unlike a normal union, they are right-aligned, thus some container_of
489
 * forward/backward casting is necessary:
490
 */
491
struct ipc_rcu_hdr
492
{
493
        int refcount;
494
        int is_vmalloc;
495
        void *data[0];
496
};
497
 
498
 
499
struct ipc_rcu_grace
500
{
501
        struct rcu_head rcu;
502
        /* "void *" makes sure alignment of following data is sane. */
503
        void *data[0];
504
};
505
 
506
struct ipc_rcu_sched
507
{
508
        struct work_struct work;
509
        /* "void *" makes sure alignment of following data is sane. */
510
        void *data[0];
511
};
512
 
513
#define HDRLEN_KMALLOC          (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
514
                                        sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
515
#define HDRLEN_VMALLOC          (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
516
                                        sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
517
 
518
static inline int rcu_use_vmalloc(int size)
519
{
520
        /* Too big for a single page? */
521
        if (HDRLEN_KMALLOC + size > PAGE_SIZE)
522
                return 1;
523
        return 0;
524
}
525
 
526
/**
527
 *      ipc_rcu_alloc   -       allocate ipc and rcu space
528
 *      @size: size desired
529
 *
530
 *      Allocate memory for the rcu header structure +  the object.
531
 *      Returns the pointer to the object.
532
 *      NULL is returned if the allocation fails.
533
 */
534
 
535
void* ipc_rcu_alloc(int size)
536
{
537
        void* out;
538
        /*
539
         * We prepend the allocation with the rcu struct, and
540
         * workqueue if necessary (for vmalloc).
541
         */
542
        if (rcu_use_vmalloc(size)) {
543
                out = vmalloc(HDRLEN_VMALLOC + size);
544
                if (out) {
545
                        out += HDRLEN_VMALLOC;
546
                        container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
547
                        container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
548
                }
549
        } else {
550
                out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
551
                if (out) {
552
                        out += HDRLEN_KMALLOC;
553
                        container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
554
                        container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
555
                }
556
        }
557
 
558
        return out;
559
}
560
 
561
void ipc_rcu_getref(void *ptr)
562
{
563
        container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
564
}
565
 
566
static void ipc_do_vfree(struct work_struct *work)
567
{
568
        vfree(container_of(work, struct ipc_rcu_sched, work));
569
}
570
 
571
/**
572
 * ipc_schedule_free - free ipc + rcu space
573
 * @head: RCU callback structure for queued work
574
 *
575
 * Since RCU callback function is called in bh,
576
 * we need to defer the vfree to schedule_work().
577
 */
578
static void ipc_schedule_free(struct rcu_head *head)
579
{
580
        struct ipc_rcu_grace *grace;
581
        struct ipc_rcu_sched *sched;
582
 
583
        grace = container_of(head, struct ipc_rcu_grace, rcu);
584
        sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
585
                                data[0]);
586
 
587
        INIT_WORK(&sched->work, ipc_do_vfree);
588
        schedule_work(&sched->work);
589
}
590
 
591
/**
592
 * ipc_immediate_free - free ipc + rcu space
593
 * @head: RCU callback structure that contains pointer to be freed
594
 *
595
 * Free from the RCU callback context.
596
 */
597
static void ipc_immediate_free(struct rcu_head *head)
598
{
599
        struct ipc_rcu_grace *free =
600
                container_of(head, struct ipc_rcu_grace, rcu);
601
        kfree(free);
602
}
603
 
604
void ipc_rcu_putref(void *ptr)
605
{
606
        if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
607
                return;
608
 
609
        if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
610
                call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
611
                                ipc_schedule_free);
612
        } else {
613
                call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
614
                                ipc_immediate_free);
615
        }
616
}
617
 
618
/**
619
 *      ipcperms        -       check IPC permissions
620
 *      @ipcp: IPC permission set
621
 *      @flag: desired permission set.
622
 *
623
 *      Check user, group, other permissions for access
624
 *      to ipc resources. return 0 if allowed
625
 */
626
 
627
int ipcperms (struct kern_ipc_perm *ipcp, short flag)
628
{       /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
629
        int requested_mode, granted_mode, err;
630
 
631
        if (unlikely((err = audit_ipc_obj(ipcp))))
632
                return err;
633
        requested_mode = (flag >> 6) | (flag >> 3) | flag;
634
        granted_mode = ipcp->mode;
635
        if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
636
                granted_mode >>= 6;
637
        else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
638
                granted_mode >>= 3;
639
        /* is there some bit set in requested_mode but not in granted_mode? */
640
        if ((requested_mode & ~granted_mode & 0007) &&
641
            !capable(CAP_IPC_OWNER))
642
                return -1;
643
 
644
        return security_ipc_permission(ipcp, flag);
645
}
646
 
647
/*
648
 * Functions to convert between the kern_ipc_perm structure and the
649
 * old/new ipc_perm structures
650
 */
651
 
652
/**
653
 *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
654
 *      @in: kernel permissions
655
 *      @out: new style IPC permissions
656
 *
657
 *      Turn the kernel object @in into a set of permissions descriptions
658
 *      for returning to userspace (@out).
659
 */
660
 
661
 
662
void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
663
{
664
        out->key        = in->key;
665
        out->uid        = in->uid;
666
        out->gid        = in->gid;
667
        out->cuid       = in->cuid;
668
        out->cgid       = in->cgid;
669
        out->mode       = in->mode;
670
        out->seq        = in->seq;
671
}
672
 
673
/**
674
 *      ipc64_perm_to_ipc_perm  -       convert new ipc permissions to old
675
 *      @in: new style IPC permissions
676
 *      @out: old style IPC permissions
677
 *
678
 *      Turn the new style permissions object @in into a compatibility
679
 *      object and store it into the @out pointer.
680
 */
681
 
682
void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
683
{
684
        out->key        = in->key;
685
        SET_UID(out->uid, in->uid);
686
        SET_GID(out->gid, in->gid);
687
        SET_UID(out->cuid, in->cuid);
688
        SET_GID(out->cgid, in->cgid);
689
        out->mode       = in->mode;
690
        out->seq        = in->seq;
691
}
692
 
693
/**
694
 * ipc_lock - Lock an ipc structure without rw_mutex held
695
 * @ids: IPC identifier set
696
 * @id: ipc id to look for
697
 *
698
 * Look for an id in the ipc ids idr and lock the associated ipc object.
699
 *
700
 * The ipc object is locked on exit.
701
 *
702
 * This is the routine that should be called when the rw_mutex is not already
703
 * held, i.e. idr tree not protected: it protects the idr tree in read mode
704
 * during the idr_find().
705
 */
706
 
707
struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
708
{
709
        struct kern_ipc_perm *out;
710
        int lid = ipcid_to_idx(id);
711
 
712
        down_read(&ids->rw_mutex);
713
 
714
        rcu_read_lock();
715
        out = idr_find(&ids->ipcs_idr, lid);
716
        if (out == NULL) {
717
                rcu_read_unlock();
718
                up_read(&ids->rw_mutex);
719
                return ERR_PTR(-EINVAL);
720
        }
721
 
722
        up_read(&ids->rw_mutex);
723
 
724
        spin_lock(&out->lock);
725
 
726
        /* ipc_rmid() may have already freed the ID while ipc_lock
727
         * was spinning: here verify that the structure is still valid
728
         */
729
        if (out->deleted) {
730
                spin_unlock(&out->lock);
731
                rcu_read_unlock();
732
                return ERR_PTR(-EINVAL);
733
        }
734
 
735
        return out;
736
}
737
 
738
/**
739
 * ipc_lock_down - Lock an ipc structure with rw_sem held
740
 * @ids: IPC identifier set
741
 * @id: ipc id to look for
742
 *
743
 * Look for an id in the ipc ids idr and lock the associated ipc object.
744
 *
745
 * The ipc object is locked on exit.
746
 *
747
 * This is the routine that should be called when the rw_mutex is already
748
 * held, i.e. idr tree protected.
749
 */
750
 
751
struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
752
{
753
        struct kern_ipc_perm *out;
754
        int lid = ipcid_to_idx(id);
755
 
756
        rcu_read_lock();
757
        out = idr_find(&ids->ipcs_idr, lid);
758
        if (out == NULL) {
759
                rcu_read_unlock();
760
                return ERR_PTR(-EINVAL);
761
        }
762
 
763
        spin_lock(&out->lock);
764
 
765
        /*
766
         * No need to verify that the structure is still valid since the
767
         * rw_mutex is held.
768
         */
769
        return out;
770
}
771
 
772
#ifdef __ARCH_WANT_IPC_PARSE_VERSION
773
 
774
 
775
/**
776
 *      ipc_parse_version       -       IPC call version
777
 *      @cmd: pointer to command
778
 *
779
 *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
780
 *      The @cmd value is turned from an encoding command and version into
781
 *      just the command code.
782
 */
783
 
784
int ipc_parse_version (int *cmd)
785
{
786
        if (*cmd & IPC_64) {
787
                *cmd ^= IPC_64;
788
                return IPC_64;
789
        } else {
790
                return IPC_OLD;
791
        }
792
}
793
 
794
#endif /* __ARCH_WANT_IPC_PARSE_VERSION */
795
 
796
#ifdef CONFIG_PROC_FS
797
struct ipc_proc_iter {
798
        struct ipc_namespace *ns;
799
        struct ipc_proc_iface *iface;
800
};
801
 
802
/*
803
 * This routine locks the ipc structure found at least at position pos.
804
 */
805
struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
806
                                        loff_t *new_pos)
807
{
808
        struct kern_ipc_perm *ipc;
809
        int total, id;
810
 
811
        total = 0;
812
        for (id = 0; id < pos && total < ids->in_use; id++) {
813
                ipc = idr_find(&ids->ipcs_idr, id);
814
                if (ipc != NULL)
815
                        total++;
816
        }
817
 
818
        if (total >= ids->in_use)
819
                return NULL;
820
 
821
        for ( ; pos < IPCMNI; pos++) {
822
                ipc = idr_find(&ids->ipcs_idr, pos);
823
                if (ipc != NULL) {
824
                        *new_pos = pos + 1;
825
                        ipc_lock_by_ptr(ipc);
826
                        return ipc;
827
                }
828
        }
829
 
830
        /* Out of range - return NULL to terminate iteration */
831
        return NULL;
832
}
833
 
834
static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
835
{
836
        struct ipc_proc_iter *iter = s->private;
837
        struct ipc_proc_iface *iface = iter->iface;
838
        struct kern_ipc_perm *ipc = it;
839
 
840
        /* If we had an ipc id locked before, unlock it */
841
        if (ipc && ipc != SEQ_START_TOKEN)
842
                ipc_unlock(ipc);
843
 
844
        return sysvipc_find_ipc(iter->ns->ids[iface->ids], *pos, pos);
845
}
846
 
847
/*
848
 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
849
 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
850
 */
851
static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
852
{
853
        struct ipc_proc_iter *iter = s->private;
854
        struct ipc_proc_iface *iface = iter->iface;
855
        struct ipc_ids *ids;
856
 
857
        ids = iter->ns->ids[iface->ids];
858
 
859
        /*
860
         * Take the lock - this will be released by the corresponding
861
         * call to stop().
862
         */
863
        down_read(&ids->rw_mutex);
864
 
865
        /* pos < 0 is invalid */
866
        if (*pos < 0)
867
                return NULL;
868
 
869
        /* pos == 0 means header */
870
        if (*pos == 0)
871
                return SEQ_START_TOKEN;
872
 
873
        /* Find the (pos-1)th ipc */
874
        return sysvipc_find_ipc(ids, *pos - 1, pos);
875
}
876
 
877
static void sysvipc_proc_stop(struct seq_file *s, void *it)
878
{
879
        struct kern_ipc_perm *ipc = it;
880
        struct ipc_proc_iter *iter = s->private;
881
        struct ipc_proc_iface *iface = iter->iface;
882
        struct ipc_ids *ids;
883
 
884
        /* If we had a locked structure, release it */
885
        if (ipc && ipc != SEQ_START_TOKEN)
886
                ipc_unlock(ipc);
887
 
888
        ids = iter->ns->ids[iface->ids];
889
        /* Release the lock we took in start() */
890
        up_read(&ids->rw_mutex);
891
}
892
 
893
static int sysvipc_proc_show(struct seq_file *s, void *it)
894
{
895
        struct ipc_proc_iter *iter = s->private;
896
        struct ipc_proc_iface *iface = iter->iface;
897
 
898
        if (it == SEQ_START_TOKEN)
899
                return seq_puts(s, iface->header);
900
 
901
        return iface->show(s, it);
902
}
903
 
904
static struct seq_operations sysvipc_proc_seqops = {
905
        .start = sysvipc_proc_start,
906
        .stop  = sysvipc_proc_stop,
907
        .next  = sysvipc_proc_next,
908
        .show  = sysvipc_proc_show,
909
};
910
 
911
static int sysvipc_proc_open(struct inode *inode, struct file *file)
912
{
913
        int ret;
914
        struct seq_file *seq;
915
        struct ipc_proc_iter *iter;
916
 
917
        ret = -ENOMEM;
918
        iter = kmalloc(sizeof(*iter), GFP_KERNEL);
919
        if (!iter)
920
                goto out;
921
 
922
        ret = seq_open(file, &sysvipc_proc_seqops);
923
        if (ret)
924
                goto out_kfree;
925
 
926
        seq = file->private_data;
927
        seq->private = iter;
928
 
929
        iter->iface = PDE(inode)->data;
930
        iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
931
out:
932
        return ret;
933
out_kfree:
934
        kfree(iter);
935
        goto out;
936
}
937
 
938
static int sysvipc_proc_release(struct inode *inode, struct file *file)
939
{
940
        struct seq_file *seq = file->private_data;
941
        struct ipc_proc_iter *iter = seq->private;
942
        put_ipc_ns(iter->ns);
943
        return seq_release_private(inode, file);
944
}
945
 
946
static const struct file_operations sysvipc_proc_fops = {
947
        .open    = sysvipc_proc_open,
948
        .read    = seq_read,
949
        .llseek  = seq_lseek,
950
        .release = sysvipc_proc_release,
951
};
952
#endif /* CONFIG_PROC_FS */

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