blk: rq_data_dir() should not return a boolean
[cris-mirror.git] / ipc / util.c
blobbe4230020a1f718c31b02012554600c710b928b9
1 /*
2 * linux/ipc/util.c
3 * Copyright (C) 1992 Krishna Balasubramanian
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>
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()
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/
39 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
40 * see sem_lock().
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>
63 #include <asm/unistd.h>
65 #include "util.h"
67 struct ipc_proc_iface {
68 const char *path;
69 const char *header;
70 int ids;
71 int (*show)(struct seq_file *, void *);
74 /**
75 * ipc_init - initialise ipc subsystem
77 * The various sysv ipc resources (semaphores, messages and shared
78 * memory) are initialised.
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.
84 static int __init ipc_init(void)
86 sem_init();
87 msg_init();
88 shm_init();
89 return 0;
91 device_initcall(ipc_init);
93 /**
94 * ipc_init_ids - initialise ipc identifiers
95 * @ids: ipc identifier set
97 * Set up the sequence range to use for the ipc identifier range (limited
98 * below IPCMNI) then initialise the ids idr.
100 void ipc_init_ids(struct ipc_ids *ids)
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);
109 #ifdef CONFIG_PROC_FS
110 static const struct file_operations sysvipc_proc_fops;
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.
118 void __init ipc_init_proc_interface(const char *path, const char *header,
119 int ids, int (*show)(struct seq_file *, void *))
121 struct proc_dir_entry *pde;
122 struct ipc_proc_iface *iface;
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;
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);
140 #endif
143 * ipc_findkey - find a key in an ipc identifier set
144 * @ids: ipc identifier set
145 * @key: key to find
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
150 * Called with ipc_ids.rwsem held.
152 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
154 struct kern_ipc_perm *ipc;
155 int next_id;
156 int total;
158 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
159 ipc = idr_find(&ids->ipcs_idr, next_id);
161 if (ipc == NULL)
162 continue;
164 if (ipc->key != key) {
165 total++;
166 continue;
169 rcu_read_lock();
170 ipc_lock_object(ipc);
171 return ipc;
174 return NULL;
178 * ipc_get_maxid - get the last assigned id
179 * @ids: ipc identifier set
181 * Called with ipc_ids.rwsem held.
183 int ipc_get_maxid(struct ipc_ids *ids)
185 struct kern_ipc_perm *ipc;
186 int max_id = -1;
187 int total, id;
189 if (ids->in_use == 0)
190 return -1;
192 if (ids->in_use == IPCMNI)
193 return IPCMNI - 1;
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++;
204 return max_id;
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
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.
218 * Called with writer ipc_ids.rwsem held.
220 int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
222 kuid_t euid;
223 kgid_t egid;
224 int id;
225 int next_id = ids->next_id;
227 if (size > IPCMNI)
228 size = IPCMNI;
230 if (ids->in_use >= size)
231 return -ENOSPC;
233 idr_preload(GFP_KERNEL);
235 spin_lock_init(&new->lock);
236 new->deleted = false;
237 rcu_read_lock();
238 spin_lock(&new->lock);
240 id = idr_alloc(&ids->ipcs_idr, new,
241 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
242 GFP_NOWAIT);
243 idr_preload_end();
244 if (id < 0) {
245 spin_unlock(&new->lock);
246 rcu_read_unlock();
247 return id;
250 ids->in_use++;
252 current_euid_egid(&euid, &egid);
253 new->cuid = new->uid = euid;
254 new->gid = new->cgid = egid;
256 if (next_id < 0) {
257 new->seq = ids->seq++;
258 if (ids->seq > IPCID_SEQ_MAX)
259 ids->seq = 0;
260 } else {
261 new->seq = ipcid_to_seqx(next_id);
262 ids->next_id = -1;
265 new->id = ipc_buildid(id, new->seq);
266 return id;
270 * ipcget_new - create a new ipc object
271 * @ns: ipc namespace
272 * @ids: ipc identifier set
273 * @ops: the actual creation routine to call
274 * @params: its parameters
276 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
277 * when the key is IPC_PRIVATE.
279 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
280 const struct ipc_ops *ops, struct ipc_params *params)
282 int err;
284 down_write(&ids->rwsem);
285 err = ops->getnew(ns, params);
286 up_write(&ids->rwsem);
287 return err;
291 * ipc_check_perms - check security and permissions for an ipc object
292 * @ns: ipc namespace
293 * @ipcp: ipc permission set
294 * @ops: the actual security routine to call
295 * @params: its parameters
297 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
298 * when the key is not IPC_PRIVATE and that key already exists in the
299 * ds IDR.
301 * On success, the ipc id is returned.
303 * It is called with ipc_ids.rwsem and ipcp->lock held.
305 static int ipc_check_perms(struct ipc_namespace *ns,
306 struct kern_ipc_perm *ipcp,
307 const struct ipc_ops *ops,
308 struct ipc_params *params)
310 int err;
312 if (ipcperms(ns, ipcp, params->flg))
313 err = -EACCES;
314 else {
315 err = ops->associate(ipcp, params->flg);
316 if (!err)
317 err = ipcp->id;
320 return err;
324 * ipcget_public - get an ipc object or create a new one
325 * @ns: ipc namespace
326 * @ids: ipc identifier set
327 * @ops: the actual creation routine to call
328 * @params: its parameters
330 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
331 * when the key is not IPC_PRIVATE.
332 * It adds a new entry if the key is not found and does some permission
333 * / security checkings if the key is found.
335 * On success, the ipc id is returned.
337 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
338 const struct ipc_ops *ops, struct ipc_params *params)
340 struct kern_ipc_perm *ipcp;
341 int flg = params->flg;
342 int err;
345 * Take the lock as a writer since we are potentially going to add
346 * a new entry + read locks are not "upgradable"
348 down_write(&ids->rwsem);
349 ipcp = ipc_findkey(ids, params->key);
350 if (ipcp == NULL) {
351 /* key not used */
352 if (!(flg & IPC_CREAT))
353 err = -ENOENT;
354 else
355 err = ops->getnew(ns, params);
356 } else {
357 /* ipc object has been locked by ipc_findkey() */
359 if (flg & IPC_CREAT && flg & IPC_EXCL)
360 err = -EEXIST;
361 else {
362 err = 0;
363 if (ops->more_checks)
364 err = ops->more_checks(ipcp, params);
365 if (!err)
367 * ipc_check_perms returns the IPC id on
368 * success
370 err = ipc_check_perms(ns, ipcp, ops, params);
372 ipc_unlock(ipcp);
374 up_write(&ids->rwsem);
376 return err;
381 * ipc_rmid - remove an ipc identifier
382 * @ids: ipc identifier set
383 * @ipcp: ipc perm structure containing the identifier to remove
385 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
386 * before this function is called, and remain locked on the exit.
388 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
390 int lid = ipcid_to_idx(ipcp->id);
392 idr_remove(&ids->ipcs_idr, lid);
393 ids->in_use--;
394 ipcp->deleted = true;
398 * ipc_alloc - allocate ipc space
399 * @size: size desired
401 * Allocate memory from the appropriate pools and return a pointer to it.
402 * NULL is returned if the allocation fails
404 void *ipc_alloc(int size)
406 void *out;
407 if (size > PAGE_SIZE)
408 out = vmalloc(size);
409 else
410 out = kmalloc(size, GFP_KERNEL);
411 return out;
415 * ipc_free - free ipc space
416 * @ptr: pointer returned by ipc_alloc
417 * @size: size of block
419 * Free a block created with ipc_alloc(). The caller must know the size
420 * used in the allocation call.
422 void ipc_free(void *ptr, int size)
424 if (size > PAGE_SIZE)
425 vfree(ptr);
426 else
427 kfree(ptr);
431 * ipc_rcu_alloc - allocate ipc and rcu space
432 * @size: size desired
434 * Allocate memory for the rcu header structure + the object.
435 * Returns the pointer to the object or NULL upon failure.
437 void *ipc_rcu_alloc(int size)
440 * We prepend the allocation with the rcu struct
442 struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
443 if (unlikely(!out))
444 return NULL;
445 atomic_set(&out->refcount, 1);
446 return out + 1;
449 int ipc_rcu_getref(void *ptr)
451 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
453 return atomic_inc_not_zero(&p->refcount);
456 void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
458 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
460 if (!atomic_dec_and_test(&p->refcount))
461 return;
463 call_rcu(&p->rcu, func);
466 void ipc_rcu_free(struct rcu_head *head)
468 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
470 kvfree(p);
474 * ipcperms - check ipc permissions
475 * @ns: ipc namespace
476 * @ipcp: ipc permission set
477 * @flag: desired permission set
479 * Check user, group, other permissions for access
480 * to ipc resources. return 0 if allowed
482 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
484 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
486 kuid_t euid = current_euid();
487 int requested_mode, granted_mode;
489 audit_ipc_obj(ipcp);
490 requested_mode = (flag >> 6) | (flag >> 3) | flag;
491 granted_mode = ipcp->mode;
492 if (uid_eq(euid, ipcp->cuid) ||
493 uid_eq(euid, ipcp->uid))
494 granted_mode >>= 6;
495 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
496 granted_mode >>= 3;
497 /* is there some bit set in requested_mode but not in granted_mode? */
498 if ((requested_mode & ~granted_mode & 0007) &&
499 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
500 return -1;
502 return security_ipc_permission(ipcp, flag);
506 * Functions to convert between the kern_ipc_perm structure and the
507 * old/new ipc_perm structures
511 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
512 * @in: kernel permissions
513 * @out: new style ipc permissions
515 * Turn the kernel object @in into a set of permissions descriptions
516 * for returning to userspace (@out).
518 void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
520 out->key = in->key;
521 out->uid = from_kuid_munged(current_user_ns(), in->uid);
522 out->gid = from_kgid_munged(current_user_ns(), in->gid);
523 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
524 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
525 out->mode = in->mode;
526 out->seq = in->seq;
530 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
531 * @in: new style ipc permissions
532 * @out: old style ipc permissions
534 * Turn the new style permissions object @in into a compatibility
535 * object and store it into the @out pointer.
537 void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
539 out->key = in->key;
540 SET_UID(out->uid, in->uid);
541 SET_GID(out->gid, in->gid);
542 SET_UID(out->cuid, in->cuid);
543 SET_GID(out->cgid, in->cgid);
544 out->mode = in->mode;
545 out->seq = in->seq;
549 * ipc_obtain_object
550 * @ids: ipc identifier set
551 * @id: ipc id to look for
553 * Look for an id in the ipc ids idr and return associated ipc object.
555 * Call inside the RCU critical section.
556 * The ipc object is *not* locked on exit.
558 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
560 struct kern_ipc_perm *out;
561 int lid = ipcid_to_idx(id);
563 out = idr_find(&ids->ipcs_idr, lid);
564 if (!out)
565 return ERR_PTR(-EINVAL);
567 return out;
571 * ipc_lock - lock an ipc structure without rwsem held
572 * @ids: ipc identifier set
573 * @id: ipc id to look for
575 * Look for an id in the ipc ids idr and lock the associated ipc object.
577 * The ipc object is locked on successful exit.
579 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
581 struct kern_ipc_perm *out;
583 rcu_read_lock();
584 out = ipc_obtain_object_idr(ids, id);
585 if (IS_ERR(out))
586 goto err;
588 spin_lock(&out->lock);
591 * ipc_rmid() may have already freed the ID while ipc_lock()
592 * was spinning: here verify that the structure is still valid.
593 * Upon races with RMID, return -EIDRM, thus indicating that
594 * the ID points to a removed identifier.
596 if (ipc_valid_object(out))
597 return out;
599 spin_unlock(&out->lock);
600 out = ERR_PTR(-EIDRM);
601 err:
602 rcu_read_unlock();
603 return out;
607 * ipc_obtain_object_check
608 * @ids: ipc identifier set
609 * @id: ipc id to look for
611 * Similar to ipc_obtain_object_idr() but also checks
612 * the ipc object reference counter.
614 * Call inside the RCU critical section.
615 * The ipc object is *not* locked on exit.
617 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
619 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
621 if (IS_ERR(out))
622 goto out;
624 if (ipc_checkid(out, id))
625 return ERR_PTR(-EINVAL);
626 out:
627 return out;
631 * ipcget - Common sys_*get() code
632 * @ns: namespace
633 * @ids: ipc identifier set
634 * @ops: operations to be called on ipc object creation, permission checks
635 * and further checks
636 * @params: the parameters needed by the previous operations.
638 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
640 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
641 const struct ipc_ops *ops, struct ipc_params *params)
643 if (params->key == IPC_PRIVATE)
644 return ipcget_new(ns, ids, ops, params);
645 else
646 return ipcget_public(ns, ids, ops, params);
650 * ipc_update_perm - update the permissions of an ipc object
651 * @in: the permission given as input.
652 * @out: the permission of the ipc to set.
654 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
656 kuid_t uid = make_kuid(current_user_ns(), in->uid);
657 kgid_t gid = make_kgid(current_user_ns(), in->gid);
658 if (!uid_valid(uid) || !gid_valid(gid))
659 return -EINVAL;
661 out->uid = uid;
662 out->gid = gid;
663 out->mode = (out->mode & ~S_IRWXUGO)
664 | (in->mode & S_IRWXUGO);
666 return 0;
670 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
671 * @ns: ipc namespace
672 * @ids: the table of ids where to look for the ipc
673 * @id: the id of the ipc to retrieve
674 * @cmd: the cmd to check
675 * @perm: the permission to set
676 * @extra_perm: one extra permission parameter used by msq
678 * This function does some common audit and permissions check for some IPC_XXX
679 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
680 * It must be called without any lock held and
681 * - retrieves the ipc with the given id in the given table.
682 * - performs some audit and permission check, depending on the given cmd
683 * - returns a pointer to the ipc object or otherwise, the corresponding error.
685 * Call holding the both the rwsem and the rcu read lock.
687 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
688 struct ipc_ids *ids, int id, int cmd,
689 struct ipc64_perm *perm, int extra_perm)
691 kuid_t euid;
692 int err = -EPERM;
693 struct kern_ipc_perm *ipcp;
695 ipcp = ipc_obtain_object_check(ids, id);
696 if (IS_ERR(ipcp)) {
697 err = PTR_ERR(ipcp);
698 goto err;
701 audit_ipc_obj(ipcp);
702 if (cmd == IPC_SET)
703 audit_ipc_set_perm(extra_perm, perm->uid,
704 perm->gid, perm->mode);
706 euid = current_euid();
707 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
708 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
709 return ipcp; /* successful lookup */
710 err:
711 return ERR_PTR(err);
714 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
718 * ipc_parse_version - ipc call version
719 * @cmd: pointer to command
721 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
722 * The @cmd value is turned from an encoding command and version into
723 * just the command code.
725 int ipc_parse_version(int *cmd)
727 if (*cmd & IPC_64) {
728 *cmd ^= IPC_64;
729 return IPC_64;
730 } else {
731 return IPC_OLD;
735 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
737 #ifdef CONFIG_PROC_FS
738 struct ipc_proc_iter {
739 struct ipc_namespace *ns;
740 struct ipc_proc_iface *iface;
744 * This routine locks the ipc structure found at least at position pos.
746 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
747 loff_t *new_pos)
749 struct kern_ipc_perm *ipc;
750 int total, id;
752 total = 0;
753 for (id = 0; id < pos && total < ids->in_use; id++) {
754 ipc = idr_find(&ids->ipcs_idr, id);
755 if (ipc != NULL)
756 total++;
759 if (total >= ids->in_use)
760 return NULL;
762 for (; pos < IPCMNI; pos++) {
763 ipc = idr_find(&ids->ipcs_idr, pos);
764 if (ipc != NULL) {
765 *new_pos = pos + 1;
766 rcu_read_lock();
767 ipc_lock_object(ipc);
768 return ipc;
772 /* Out of range - return NULL to terminate iteration */
773 return NULL;
776 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
778 struct ipc_proc_iter *iter = s->private;
779 struct ipc_proc_iface *iface = iter->iface;
780 struct kern_ipc_perm *ipc = it;
782 /* If we had an ipc id locked before, unlock it */
783 if (ipc && ipc != SEQ_START_TOKEN)
784 ipc_unlock(ipc);
786 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
790 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
791 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
793 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
795 struct ipc_proc_iter *iter = s->private;
796 struct ipc_proc_iface *iface = iter->iface;
797 struct ipc_ids *ids;
799 ids = &iter->ns->ids[iface->ids];
802 * Take the lock - this will be released by the corresponding
803 * call to stop().
805 down_read(&ids->rwsem);
807 /* pos < 0 is invalid */
808 if (*pos < 0)
809 return NULL;
811 /* pos == 0 means header */
812 if (*pos == 0)
813 return SEQ_START_TOKEN;
815 /* Find the (pos-1)th ipc */
816 return sysvipc_find_ipc(ids, *pos - 1, pos);
819 static void sysvipc_proc_stop(struct seq_file *s, void *it)
821 struct kern_ipc_perm *ipc = it;
822 struct ipc_proc_iter *iter = s->private;
823 struct ipc_proc_iface *iface = iter->iface;
824 struct ipc_ids *ids;
826 /* If we had a locked structure, release it */
827 if (ipc && ipc != SEQ_START_TOKEN)
828 ipc_unlock(ipc);
830 ids = &iter->ns->ids[iface->ids];
831 /* Release the lock we took in start() */
832 up_read(&ids->rwsem);
835 static int sysvipc_proc_show(struct seq_file *s, void *it)
837 struct ipc_proc_iter *iter = s->private;
838 struct ipc_proc_iface *iface = iter->iface;
840 if (it == SEQ_START_TOKEN) {
841 seq_puts(s, iface->header);
842 return 0;
845 return iface->show(s, it);
848 static const struct seq_operations sysvipc_proc_seqops = {
849 .start = sysvipc_proc_start,
850 .stop = sysvipc_proc_stop,
851 .next = sysvipc_proc_next,
852 .show = sysvipc_proc_show,
855 static int sysvipc_proc_open(struct inode *inode, struct file *file)
857 struct ipc_proc_iter *iter;
859 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
860 if (!iter)
861 return -ENOMEM;
863 iter->iface = PDE_DATA(inode);
864 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
866 return 0;
869 static int sysvipc_proc_release(struct inode *inode, struct file *file)
871 struct seq_file *seq = file->private_data;
872 struct ipc_proc_iter *iter = seq->private;
873 put_ipc_ns(iter->ns);
874 return seq_release_private(inode, file);
877 static const struct file_operations sysvipc_proc_fops = {
878 .open = sysvipc_proc_open,
879 .read = seq_read,
880 .llseek = seq_lseek,
881 .release = sysvipc_proc_release,
883 #endif /* CONFIG_PROC_FS */