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1 /*
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 * General sysv ipc locking scheme:
20 * rcu_read_lock()
21 * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
22 * tree.
23 * - perform initial checks (capabilities, auditing and permission,
24 * etc).
25 * - perform read-only operations, such as STAT, INFO commands.
26 * acquire the ipc lock (kern_ipc_perm.lock) through
27 * ipc_lock_object()
28 * - perform data updates, such as SET, RMID commands and
29 * mechanism-specific operations (semop/semtimedop,
30 * msgsnd/msgrcv, shmat/shmdt).
31 * drop the ipc lock, through ipc_unlock_object().
32 * rcu_read_unlock()
33 *
34 * The ids->rwsem must be taken when:
35 * - creating, removing and iterating the existing entries in ipc
36 * identifier sets.
37 * - iterating through files under /proc/sysvipc/
38 *
39 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
40 * see sem_lock().
41 */
42
43 #include <linux/mm.h>
44 #include <linux/shm.h>
45 #include <linux/init.h>
46 #include <linux/msg.h>
47 #include <linux/vmalloc.h>
48 #include <linux/slab.h>
49 #include <linux/notifier.h>
50 #include <linux/capability.h>
51 #include <linux/highuid.h>
52 #include <linux/security.h>
53 #include <linux/rcupdate.h>
54 #include <linux/workqueue.h>
55 #include <linux/seq_file.h>
56 #include <linux/proc_fs.h>
57 #include <linux/audit.h>
58 #include <linux/nsproxy.h>
59 #include <linux/rwsem.h>
60 #include <linux/memory.h>
61 #include <linux/ipc_namespace.h>
62
63 #include <asm/unistd.h>
64
65 #include "util.h"
66
67 struct ipc_proc_iface {
68 const char *path;
69 const char *header;
70 int ids;
71 int (*show)(struct seq_file *, void *);
72 };
73
74 /**
75 * ipc_init - initialise ipc subsystem
76 *
77 * The various sysv ipc resources (semaphores, messages and shared
78 * memory) are initialised.
79 *
80 * A callback routine is registered into the memory hotplug notifier
81 * chain: since msgmni scales to lowmem this callback routine will be
82 * called upon successful memory add / remove to recompute msmgni.
83 */
84 static int __init ipc_init(void)
85 {
86 sem_init();
87 msg_init();
88 shm_init();
89 return 0;
90 }
91 device_initcall(ipc_init);
92
93 /**
94 * ipc_init_ids - initialise ipc identifiers
95 * @ids: ipc identifier set
96 *
97 * Set up the sequence range to use for the ipc identifier range (limited
98 * below IPCMNI) then initialise the ids idr.
99 */
100 void ipc_init_ids(struct ipc_ids *ids)
101 {
102 ids->in_use = 0;
103 ids->seq = 0;
104 ids->next_id = -1;
105 init_rwsem(&ids->rwsem);
106 idr_init(&ids->ipcs_idr);
107 }
108
109 #ifdef CONFIG_PROC_FS
110 static const struct file_operations sysvipc_proc_fops;
111 /**
112 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
113 * @path: Path in procfs
114 * @header: Banner to be printed at the beginning of the file.
115 * @ids: ipc id table to iterate.
116 * @show: show routine.
117 */
118 void __init ipc_init_proc_interface(const char *path, const char *header,
119 int ids, int (*show)(struct seq_file *, void *))
120 {
121 struct proc_dir_entry *pde;
122 struct ipc_proc_iface *iface;
123
124 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
125 if (!iface)
126 return;
127 iface->path = path;
128 iface->header = header;
129 iface->ids = ids;
130 iface->show = show;
131
132 pde = proc_create_data(path,
133 S_IRUGO, /* world readable */
134 NULL, /* parent dir */
135 &sysvipc_proc_fops,
136 iface);
137 if (!pde)
138 kfree(iface);
139 }
140 #endif
141
142 /**
143 * ipc_findkey - find a key in an ipc identifier set
144 * @ids: ipc identifier set
145 * @key: key to find
146 *
147 * Returns the locked pointer to the ipc structure if found or NULL
148 * otherwise. If key is found ipc points to the owning ipc structure
149 *
150 * Called with ipc_ids.rwsem held.
151 */
152 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
153 {
154 struct kern_ipc_perm *ipc;
155 int next_id;
156 int total;
157
158 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
159 ipc = idr_find(&ids->ipcs_idr, next_id);
160
161 if (ipc == NULL)
162 continue;
163
164 if (ipc->key != key) {
165 total++;
166 continue;
167 }
168
169 rcu_read_lock();
170 ipc_lock_object(ipc);
171 return ipc;
172 }
173
174 return NULL;
175 }
176
177 /**
178 * ipc_get_maxid - get the last assigned id
179 * @ids: ipc identifier set
180 *
181 * Called with ipc_ids.rwsem held.
182 */
183 int ipc_get_maxid(struct ipc_ids *ids)
184 {
185 struct kern_ipc_perm *ipc;
186 int max_id = -1;
187 int total, id;
188
189 if (ids->in_use == 0)
190 return -1;
191
192 if (ids->in_use == IPCMNI)
193 return IPCMNI - 1;
194
195 /* Look for the last assigned id */
196 total = 0;
197 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
198 ipc = idr_find(&ids->ipcs_idr, id);
199 if (ipc != NULL) {
200 max_id = id;
201 total++;
202 }
203 }
204 return max_id;
205 }
206
207 /**
208 * ipc_addid - add an ipc identifier
209 * @ids: ipc identifier set
210 * @new: new ipc permission set
211 * @size: limit for the number of used ids
212 *
213 * Add an entry 'new' to the ipc ids idr. The permissions object is
214 * initialised and the first free entry is set up and the id assigned
215 * is returned. The 'new' entry is returned in a locked state on success.
216 * On failure the entry is not locked and a negative err-code is returned.
217 *
218 * Called with writer ipc_ids.rwsem held.
219 */
220 int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
221 {
222 kuid_t euid;
223 kgid_t egid;
224 int id;
225 int next_id = ids->next_id;
226
227 if (size > IPCMNI)
228 size = IPCMNI;
229
230 if (ids->in_use >= size)
231 return -ENOSPC;
232
233 idr_preload(GFP_KERNEL);
234
235 atomic_set(&new->refcount, 1);
236 spin_lock_init(&new->lock);
237 new->deleted = false;
238 rcu_read_lock();
239 spin_lock(&new->lock);
240
241 current_euid_egid(&euid, &egid);
242 new->cuid = new->uid = euid;
243 new->gid = new->cgid = egid;
244
245 id = idr_alloc(&ids->ipcs_idr, new,
246 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
247 GFP_NOWAIT);
248 idr_preload_end();
249 if (id < 0) {
250 spin_unlock(&new->lock);
251 rcu_read_unlock();
252 return id;
253 }
254
255 ids->in_use++;
256
257 if (next_id < 0) {
258 new->seq = ids->seq++;
259 if (ids->seq > IPCID_SEQ_MAX)
260 ids->seq = 0;
261 } else {
262 new->seq = ipcid_to_seqx(next_id);
263 ids->next_id = -1;
264 }
265
266 new->id = ipc_buildid(id, new->seq);
267 return id;
268 }
269
270 /**
271 * ipcget_new - create a new ipc object
272 * @ns: ipc namespace
273 * @ids: ipc identifier set
274 * @ops: the actual creation routine to call
275 * @params: its parameters
276 *
277 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
278 * when the key is IPC_PRIVATE.
279 */
280 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
281 const struct ipc_ops *ops, struct ipc_params *params)
282 {
283 int err;
284
285 down_write(&ids->rwsem);
286 err = ops->getnew(ns, params);
287 up_write(&ids->rwsem);
288 return err;
289 }
290
291 /**
292 * ipc_check_perms - check security and permissions for an ipc object
293 * @ns: ipc namespace
294 * @ipcp: ipc permission set
295 * @ops: the actual security routine to call
296 * @params: its parameters
297 *
298 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
299 * when the key is not IPC_PRIVATE and that key already exists in the
300 * ds IDR.
301 *
302 * On success, the ipc id is returned.
303 *
304 * It is called with ipc_ids.rwsem and ipcp->lock held.
305 */
306 static int ipc_check_perms(struct ipc_namespace *ns,
307 struct kern_ipc_perm *ipcp,
308 const struct ipc_ops *ops,
309 struct ipc_params *params)
310 {
311 int err;
312
313 if (ipcperms(ns, ipcp, params->flg))
314 err = -EACCES;
315 else {
316 err = ops->associate(ipcp, params->flg);
317 if (!err)
318 err = ipcp->id;
319 }
320
321 return err;
322 }
323
324 /**
325 * ipcget_public - get an ipc object or create a new one
326 * @ns: ipc namespace
327 * @ids: ipc identifier set
328 * @ops: the actual creation routine to call
329 * @params: its parameters
330 *
331 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
332 * when the key is not IPC_PRIVATE.
333 * It adds a new entry if the key is not found and does some permission
334 * / security checkings if the key is found.
335 *
336 * On success, the ipc id is returned.
337 */
338 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
339 const struct ipc_ops *ops, struct ipc_params *params)
340 {
341 struct kern_ipc_perm *ipcp;
342 int flg = params->flg;
343 int err;
344
345 /*
346 * Take the lock as a writer since we are potentially going to add
347 * a new entry + read locks are not "upgradable"
348 */
349 down_write(&ids->rwsem);
350 ipcp = ipc_findkey(ids, params->key);
351 if (ipcp == NULL) {
352 /* key not used */
353 if (!(flg & IPC_CREAT))
354 err = -ENOENT;
355 else
356 err = ops->getnew(ns, params);
357 } else {
358 /* ipc object has been locked by ipc_findkey() */
359
360 if (flg & IPC_CREAT && flg & IPC_EXCL)
361 err = -EEXIST;
362 else {
363 err = 0;
364 if (ops->more_checks)
365 err = ops->more_checks(ipcp, params);
366 if (!err)
367 /*
368 * ipc_check_perms returns the IPC id on
369 * success
370 */
371 err = ipc_check_perms(ns, ipcp, ops, params);
372 }
373 ipc_unlock(ipcp);
374 }
375 up_write(&ids->rwsem);
376
377 return err;
378 }
379
380
381 /**
382 * ipc_rmid - remove an ipc identifier
383 * @ids: ipc identifier set
384 * @ipcp: ipc perm structure containing the identifier to remove
385 *
386 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
387 * before this function is called, and remain locked on the exit.
388 */
389 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
390 {
391 int lid = ipcid_to_idx(ipcp->id);
392
393 idr_remove(&ids->ipcs_idr, lid);
394 ids->in_use--;
395 ipcp->deleted = true;
396 }
397
398 int ipc_rcu_getref(struct kern_ipc_perm *ptr)
399 {
400 return atomic_inc_not_zero(&ptr->refcount);
401 }
402
403 void ipc_rcu_putref(struct kern_ipc_perm *ptr,
404 void (*func)(struct rcu_head *head))
405 {
406 if (!atomic_dec_and_test(&ptr->refcount))
407 return;
408
409 call_rcu(&ptr->rcu, func);
410 }
411
412 /**
413 * ipcperms - check ipc permissions
414 * @ns: ipc namespace
415 * @ipcp: ipc permission set
416 * @flag: desired permission set
417 *
418 * Check user, group, other permissions for access
419 * to ipc resources. return 0 if allowed
420 *
421 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
422 */
423 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
424 {
425 kuid_t euid = current_euid();
426 int requested_mode, granted_mode;
427
428 audit_ipc_obj(ipcp);
429 requested_mode = (flag >> 6) | (flag >> 3) | flag;
430 granted_mode = ipcp->mode;
431 if (uid_eq(euid, ipcp->cuid) ||
432 uid_eq(euid, ipcp->uid))
433 granted_mode >>= 6;
434 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
435 granted_mode >>= 3;
436 /* is there some bit set in requested_mode but not in granted_mode? */
437 if ((requested_mode & ~granted_mode & 0007) &&
438 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
439 return -1;
440
441 return security_ipc_permission(ipcp, flag);
442 }
443
444 /*
445 * Functions to convert between the kern_ipc_perm structure and the
446 * old/new ipc_perm structures
447 */
448
449 /**
450 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
451 * @in: kernel permissions
452 * @out: new style ipc permissions
453 *
454 * Turn the kernel object @in into a set of permissions descriptions
455 * for returning to userspace (@out).
456 */
457 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
458 {
459 out->key = in->key;
460 out->uid = from_kuid_munged(current_user_ns(), in->uid);
461 out->gid = from_kgid_munged(current_user_ns(), in->gid);
462 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
463 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
464 out->mode = in->mode;
465 out->seq = in->seq;
466 }
467
468 /**
469 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
470 * @in: new style ipc permissions
471 * @out: old style ipc permissions
472 *
473 * Turn the new style permissions object @in into a compatibility
474 * object and store it into the @out pointer.
475 */
476 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
477 {
478 out->key = in->key;
479 SET_UID(out->uid, in->uid);
480 SET_GID(out->gid, in->gid);
481 SET_UID(out->cuid, in->cuid);
482 SET_GID(out->cgid, in->cgid);
483 out->mode = in->mode;
484 out->seq = in->seq;
485 }
486
487 /**
488 * ipc_obtain_object
489 * @ids: ipc identifier set
490 * @id: ipc id to look for
491 *
492 * Look for an id in the ipc ids idr and return associated ipc object.
493 *
494 * Call inside the RCU critical section.
495 * The ipc object is *not* locked on exit.
496 */
497 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
498 {
499 struct kern_ipc_perm *out;
500 int lid = ipcid_to_idx(id);
501
502 out = idr_find(&ids->ipcs_idr, lid);
503 if (!out)
504 return ERR_PTR(-EINVAL);
505
506 return out;
507 }
508
509 /**
510 * ipc_lock - lock an ipc structure without rwsem held
511 * @ids: ipc identifier set
512 * @id: ipc id to look for
513 *
514 * Look for an id in the ipc ids idr and lock the associated ipc object.
515 *
516 * The ipc object is locked on successful exit.
517 */
518 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
519 {
520 struct kern_ipc_perm *out;
521
522 rcu_read_lock();
523 out = ipc_obtain_object_idr(ids, id);
524 if (IS_ERR(out))
525 goto err;
526
527 spin_lock(&out->lock);
528
529 /*
530 * ipc_rmid() may have already freed the ID while ipc_lock()
531 * was spinning: here verify that the structure is still valid.
532 * Upon races with RMID, return -EIDRM, thus indicating that
533 * the ID points to a removed identifier.
534 */
535 if (ipc_valid_object(out))
536 return out;
537
538 spin_unlock(&out->lock);
539 out = ERR_PTR(-EIDRM);
540 err:
541 rcu_read_unlock();
542 return out;
543 }
544
545 /**
546 * ipc_obtain_object_check
547 * @ids: ipc identifier set
548 * @id: ipc id to look for
549 *
550 * Similar to ipc_obtain_object_idr() but also checks
551 * the ipc object reference counter.
552 *
553 * Call inside the RCU critical section.
554 * The ipc object is *not* locked on exit.
555 */
556 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
557 {
558 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
559
560 if (IS_ERR(out))
561 goto out;
562
563 if (ipc_checkid(out, id))
564 return ERR_PTR(-EINVAL);
565 out:
566 return out;
567 }
568
569 /**
570 * ipcget - Common sys_*get() code
571 * @ns: namespace
572 * @ids: ipc identifier set
573 * @ops: operations to be called on ipc object creation, permission checks
574 * and further checks
575 * @params: the parameters needed by the previous operations.
576 *
577 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
578 */
579 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
580 const struct ipc_ops *ops, struct ipc_params *params)
581 {
582 if (params->key == IPC_PRIVATE)
583 return ipcget_new(ns, ids, ops, params);
584 else
585 return ipcget_public(ns, ids, ops, params);
586 }
587
588 /**
589 * ipc_update_perm - update the permissions of an ipc object
590 * @in: the permission given as input.
591 * @out: the permission of the ipc to set.
592 */
593 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
594 {
595 kuid_t uid = make_kuid(current_user_ns(), in->uid);
596 kgid_t gid = make_kgid(current_user_ns(), in->gid);
597 if (!uid_valid(uid) || !gid_valid(gid))
598 return -EINVAL;
599
600 out->uid = uid;
601 out->gid = gid;
602 out->mode = (out->mode & ~S_IRWXUGO)
603 | (in->mode & S_IRWXUGO);
604
605 return 0;
606 }
607
608 /**
609 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
610 * @ns: ipc namespace
611 * @ids: the table of ids where to look for the ipc
612 * @id: the id of the ipc to retrieve
613 * @cmd: the cmd to check
614 * @perm: the permission to set
615 * @extra_perm: one extra permission parameter used by msq
616 *
617 * This function does some common audit and permissions check for some IPC_XXX
618 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
619 * It must be called without any lock held and:
620 *
621 * - retrieves the ipc with the given id in the given table.
622 * - performs some audit and permission check, depending on the given cmd
623 * - returns a pointer to the ipc object or otherwise, the corresponding
624 * error.
625 *
626 * Call holding the both the rwsem and the rcu read lock.
627 */
628 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
629 struct ipc_ids *ids, int id, int cmd,
630 struct ipc64_perm *perm, int extra_perm)
631 {
632 kuid_t euid;
633 int err = -EPERM;
634 struct kern_ipc_perm *ipcp;
635
636 ipcp = ipc_obtain_object_check(ids, id);
637 if (IS_ERR(ipcp)) {
638 err = PTR_ERR(ipcp);
639 goto err;
640 }
641
642 audit_ipc_obj(ipcp);
643 if (cmd == IPC_SET)
644 audit_ipc_set_perm(extra_perm, perm->uid,
645 perm->gid, perm->mode);
646
647 euid = current_euid();
648 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
649 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
650 return ipcp; /* successful lookup */
651 err:
652 return ERR_PTR(err);
653 }
654
655 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
656
657
658 /**
659 * ipc_parse_version - ipc call version
660 * @cmd: pointer to command
661 *
662 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
663 * The @cmd value is turned from an encoding command and version into
664 * just the command code.
665 */
666 int ipc_parse_version(int *cmd)
667 {
668 if (*cmd & IPC_64) {
669 *cmd ^= IPC_64;
670 return IPC_64;
671 } else {
672 return IPC_OLD;
673 }
674 }
675
676 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
677
678 #ifdef CONFIG_PROC_FS
679 struct ipc_proc_iter {
680 struct ipc_namespace *ns;
681 struct ipc_proc_iface *iface;
682 };
683
684 /*
685 * This routine locks the ipc structure found at least at position pos.
686 */
687 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
688 loff_t *new_pos)
689 {
690 struct kern_ipc_perm *ipc;
691 int total, id;
692
693 total = 0;
694 for (id = 0; id < pos && total < ids->in_use; id++) {
695 ipc = idr_find(&ids->ipcs_idr, id);
696 if (ipc != NULL)
697 total++;
698 }
699
700 if (total >= ids->in_use)
701 return NULL;
702
703 for (; pos < IPCMNI; pos++) {
704 ipc = idr_find(&ids->ipcs_idr, pos);
705 if (ipc != NULL) {
706 *new_pos = pos + 1;
707 rcu_read_lock();
708 ipc_lock_object(ipc);
709 return ipc;
710 }
711 }
712
713 /* Out of range - return NULL to terminate iteration */
714 return NULL;
715 }
716
717 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
718 {
719 struct ipc_proc_iter *iter = s->private;
720 struct ipc_proc_iface *iface = iter->iface;
721 struct kern_ipc_perm *ipc = it;
722
723 /* If we had an ipc id locked before, unlock it */
724 if (ipc && ipc != SEQ_START_TOKEN)
725 ipc_unlock(ipc);
726
727 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
728 }
729
730 /*
731 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
732 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
733 */
734 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
735 {
736 struct ipc_proc_iter *iter = s->private;
737 struct ipc_proc_iface *iface = iter->iface;
738 struct ipc_ids *ids;
739
740 ids = &iter->ns->ids[iface->ids];
741
742 /*
743 * Take the lock - this will be released by the corresponding
744 * call to stop().
745 */
746 down_read(&ids->rwsem);
747
748 /* pos < 0 is invalid */
749 if (*pos < 0)
750 return NULL;
751
752 /* pos == 0 means header */
753 if (*pos == 0)
754 return SEQ_START_TOKEN;
755
756 /* Find the (pos-1)th ipc */
757 return sysvipc_find_ipc(ids, *pos - 1, pos);
758 }
759
760 static void sysvipc_proc_stop(struct seq_file *s, void *it)
761 {
762 struct kern_ipc_perm *ipc = it;
763 struct ipc_proc_iter *iter = s->private;
764 struct ipc_proc_iface *iface = iter->iface;
765 struct ipc_ids *ids;
766
767 /* If we had a locked structure, release it */
768 if (ipc && ipc != SEQ_START_TOKEN)
769 ipc_unlock(ipc);
770
771 ids = &iter->ns->ids[iface->ids];
772 /* Release the lock we took in start() */
773 up_read(&ids->rwsem);
774 }
775
776 static int sysvipc_proc_show(struct seq_file *s, void *it)
777 {
778 struct ipc_proc_iter *iter = s->private;
779 struct ipc_proc_iface *iface = iter->iface;
780
781 if (it == SEQ_START_TOKEN) {
782 seq_puts(s, iface->header);
783 return 0;
784 }
785
786 return iface->show(s, it);
787 }
788
789 static const struct seq_operations sysvipc_proc_seqops = {
790 .start = sysvipc_proc_start,
791 .stop = sysvipc_proc_stop,
792 .next = sysvipc_proc_next,
793 .show = sysvipc_proc_show,
794 };
795
796 static int sysvipc_proc_open(struct inode *inode, struct file *file)
797 {
798 struct ipc_proc_iter *iter;
799
800 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
801 if (!iter)
802 return -ENOMEM;
803
804 iter->iface = PDE_DATA(inode);
805 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
806
807 return 0;
808 }
809
810 static int sysvipc_proc_release(struct inode *inode, struct file *file)
811 {
812 struct seq_file *seq = file->private_data;
813 struct ipc_proc_iter *iter = seq->private;
814 put_ipc_ns(iter->ns);
815 return seq_release_private(inode, file);
816 }
817
818 static const struct file_operations sysvipc_proc_fops = {
819 .open = sysvipc_proc_open,
820 .read = seq_read,
821 .llseek = seq_lseek,
822 .release = sysvipc_proc_release,
823 };
824 #endif /* CONFIG_PROC_FS */