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
17 * Pavel Emelianov <xemul@openvz.org>
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/notifier.h>
27 #include <linux/capability.h>
28 #include <linux/highuid.h>
29 #include <linux/security.h>
30 #include <linux/rcupdate.h>
31 #include <linux/workqueue.h>
32 #include <linux/seq_file.h>
33 #include <linux/proc_fs.h>
34 #include <linux/audit.h>
35 #include <linux/nsproxy.h>
36 #include <linux/rwsem.h>
37 #include <linux/memory.h>
38 #include <linux/ipc_namespace.h>
40 #include <asm/unistd.h>
44 struct ipc_proc_iface
{
48 int (*show
)(struct seq_file
*, void *);
51 static void ipc_memory_notifier(struct work_struct
*work
)
53 ipcns_notify(IPCNS_MEMCHANGED
);
56 static int ipc_memory_callback(struct notifier_block
*self
,
57 unsigned long action
, void *arg
)
59 static DECLARE_WORK(ipc_memory_wq
, ipc_memory_notifier
);
62 case MEM_ONLINE
: /* memory successfully brought online */
63 case MEM_OFFLINE
: /* or offline: it's time to recompute msgmni */
65 * This is done by invoking the ipcns notifier chain with the
66 * IPC_MEMCHANGED event.
67 * In order not to keep the lock on the hotplug memory chain
68 * for too long, queue a work item that will, when waken up,
69 * activate the ipcns notification chain.
70 * No need to keep several ipc work items on the queue.
72 if (!work_pending(&ipc_memory_wq
))
73 schedule_work(&ipc_memory_wq
);
75 case MEM_GOING_ONLINE
:
76 case MEM_GOING_OFFLINE
:
77 case MEM_CANCEL_ONLINE
:
78 case MEM_CANCEL_OFFLINE
:
86 static struct notifier_block ipc_memory_nb
= {
87 .notifier_call
= ipc_memory_callback
,
88 .priority
= IPC_CALLBACK_PRI
,
92 * ipc_init - initialise IPC subsystem
94 * The various system5 IPC resources (semaphores, messages and shared
95 * memory) are initialised
96 * A callback routine is registered into the memory hotplug notifier
97 * chain: since msgmni scales to lowmem this callback routine will be
98 * called upon successful memory add / remove to recompute msmgni.
101 static int __init
ipc_init(void)
106 register_hotmemory_notifier(&ipc_memory_nb
);
107 register_ipcns_notifier(&init_ipc_ns
);
110 __initcall(ipc_init
);
113 * ipc_init_ids - initialise IPC identifiers
114 * @ids: Identifier set
116 * Set up the sequence range to use for the ipc identifier range (limited
117 * below IPCMNI) then initialise the ids idr.
120 void ipc_init_ids(struct ipc_ids
*ids
)
122 init_rwsem(&ids
->rw_mutex
);
128 int seq_limit
= INT_MAX
/SEQ_MULTIPLIER
;
129 if (seq_limit
> USHRT_MAX
)
130 ids
->seq_max
= USHRT_MAX
;
132 ids
->seq_max
= seq_limit
;
135 idr_init(&ids
->ipcs_idr
);
138 #ifdef CONFIG_PROC_FS
139 static const struct file_operations sysvipc_proc_fops
;
141 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
142 * @path: Path in procfs
143 * @header: Banner to be printed at the beginning of the file.
144 * @ids: ipc id table to iterate.
145 * @show: show routine.
147 void __init
ipc_init_proc_interface(const char *path
, const char *header
,
148 int ids
, int (*show
)(struct seq_file
*, void *))
150 struct proc_dir_entry
*pde
;
151 struct ipc_proc_iface
*iface
;
153 iface
= kmalloc(sizeof(*iface
), GFP_KERNEL
);
157 iface
->header
= header
;
161 pde
= proc_create_data(path
,
162 S_IRUGO
, /* world readable */
163 NULL
, /* parent dir */
173 * ipc_findkey - find a key in an ipc identifier set
174 * @ids: Identifier set
175 * @key: The key to find
177 * Requires ipc_ids.rw_mutex locked.
178 * Returns the LOCKED pointer to the ipc structure if found or NULL
180 * If key is found ipc points to the owning ipc structure
183 static struct kern_ipc_perm
*ipc_findkey(struct ipc_ids
*ids
, key_t key
)
185 struct kern_ipc_perm
*ipc
;
189 for (total
= 0, next_id
= 0; total
< ids
->in_use
; next_id
++) {
190 ipc
= idr_find(&ids
->ipcs_idr
, next_id
);
195 if (ipc
->key
!= key
) {
200 ipc_lock_by_ptr(ipc
);
208 * ipc_get_maxid - get the last assigned id
209 * @ids: IPC identifier set
211 * Called with ipc_ids.rw_mutex held.
214 int ipc_get_maxid(struct ipc_ids
*ids
)
216 struct kern_ipc_perm
*ipc
;
220 if (ids
->in_use
== 0)
223 if (ids
->in_use
== IPCMNI
)
226 /* Look for the last assigned id */
228 for (id
= 0; id
< IPCMNI
&& total
< ids
->in_use
; id
++) {
229 ipc
= idr_find(&ids
->ipcs_idr
, id
);
239 * ipc_addid - add an IPC identifier
240 * @ids: IPC identifier set
241 * @new: new IPC permission set
242 * @size: limit for the number of used ids
244 * Add an entry 'new' to the IPC ids idr. The permissions object is
245 * initialised and the first free entry is set up and the id assigned
246 * is returned. The 'new' entry is returned in a locked state on success.
247 * On failure the entry is not locked and a negative err-code is returned.
249 * Called with ipc_ids.rw_mutex held as a writer.
252 int ipc_addid(struct ipc_ids
* ids
, struct kern_ipc_perm
* new, int size
)
257 int next_id
= ids
->next_id
;
262 if (ids
->in_use
>= size
)
265 idr_preload(GFP_KERNEL
);
267 spin_lock_init(&new->lock
);
270 spin_lock(&new->lock
);
272 id
= idr_alloc(&ids
->ipcs_idr
, new,
273 (next_id
< 0) ? 0 : ipcid_to_idx(next_id
), 0,
277 spin_unlock(&new->lock
);
284 current_euid_egid(&euid
, &egid
);
285 new->cuid
= new->uid
= euid
;
286 new->gid
= new->cgid
= egid
;
289 new->seq
= ids
->seq
++;
290 if (ids
->seq
> ids
->seq_max
)
293 new->seq
= ipcid_to_seqx(next_id
);
297 new->id
= ipc_buildid(id
, new->seq
);
302 * ipcget_new - create a new ipc object
304 * @ids: IPC identifer set
305 * @ops: the actual creation routine to call
306 * @params: its parameters
308 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
309 * when the key is IPC_PRIVATE.
311 static int ipcget_new(struct ipc_namespace
*ns
, struct ipc_ids
*ids
,
312 struct ipc_ops
*ops
, struct ipc_params
*params
)
316 down_write(&ids
->rw_mutex
);
317 err
= ops
->getnew(ns
, params
);
318 up_write(&ids
->rw_mutex
);
323 * ipc_check_perms - check security and permissions for an IPC
325 * @ipcp: ipc permission set
326 * @ops: the actual security routine to call
327 * @params: its parameters
329 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
330 * when the key is not IPC_PRIVATE and that key already exists in the
333 * On success, the IPC id is returned.
335 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
337 static int ipc_check_perms(struct ipc_namespace
*ns
,
338 struct kern_ipc_perm
*ipcp
,
340 struct ipc_params
*params
)
344 if (ipcperms(ns
, ipcp
, params
->flg
))
347 err
= ops
->associate(ipcp
, params
->flg
);
356 * ipcget_public - get an ipc object or create a new one
358 * @ids: IPC identifer set
359 * @ops: the actual creation routine to call
360 * @params: its parameters
362 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
363 * when the key is not IPC_PRIVATE.
364 * It adds a new entry if the key is not found and does some permission
365 * / security checkings if the key is found.
367 * On success, the ipc id is returned.
369 static int ipcget_public(struct ipc_namespace
*ns
, struct ipc_ids
*ids
,
370 struct ipc_ops
*ops
, struct ipc_params
*params
)
372 struct kern_ipc_perm
*ipcp
;
373 int flg
= params
->flg
;
377 * Take the lock as a writer since we are potentially going to add
378 * a new entry + read locks are not "upgradable"
380 down_write(&ids
->rw_mutex
);
381 ipcp
= ipc_findkey(ids
, params
->key
);
384 if (!(flg
& IPC_CREAT
))
387 err
= ops
->getnew(ns
, params
);
389 /* ipc object has been locked by ipc_findkey() */
391 if (flg
& IPC_CREAT
&& flg
& IPC_EXCL
)
395 if (ops
->more_checks
)
396 err
= ops
->more_checks(ipcp
, params
);
399 * ipc_check_perms returns the IPC id on
402 err
= ipc_check_perms(ns
, ipcp
, ops
, params
);
406 up_write(&ids
->rw_mutex
);
413 * ipc_rmid - remove an IPC identifier
414 * @ids: IPC identifier set
415 * @ipcp: ipc perm structure containing the identifier to remove
417 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
418 * before this function is called, and remain locked on the exit.
421 void ipc_rmid(struct ipc_ids
*ids
, struct kern_ipc_perm
*ipcp
)
423 int lid
= ipcid_to_idx(ipcp
->id
);
425 idr_remove(&ids
->ipcs_idr
, lid
);
435 * ipc_alloc - allocate ipc space
436 * @size: size desired
438 * Allocate memory from the appropriate pools and return a pointer to it.
439 * NULL is returned if the allocation fails
442 void *ipc_alloc(int size
)
448 out
= kmalloc(size
, GFP_KERNEL
);
453 * ipc_free - free ipc space
454 * @ptr: pointer returned by ipc_alloc
455 * @size: size of block
457 * Free a block created with ipc_alloc(). The caller must know the size
458 * used in the allocation call.
461 void ipc_free(void* ptr
, int size
)
471 * There are three headers that are prepended to the actual allocation:
472 * - during use: ipc_rcu_hdr.
473 * - during the rcu grace period: ipc_rcu_grace.
474 * - [only if vmalloc]: ipc_rcu_sched.
475 * Their lifetime doesn't overlap, thus the headers share the same memory.
476 * Unlike a normal union, they are right-aligned, thus some container_of
477 * forward/backward casting is necessary:
490 /* "void *" makes sure alignment of following data is sane. */
496 struct work_struct work
;
497 /* "void *" makes sure alignment of following data is sane. */
501 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
502 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
503 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
504 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
506 static inline int rcu_use_vmalloc(int size
)
508 /* Too big for a single page? */
509 if (HDRLEN_KMALLOC
+ size
> PAGE_SIZE
)
515 * ipc_rcu_alloc - allocate ipc and rcu space
516 * @size: size desired
518 * Allocate memory for the rcu header structure + the object.
519 * Returns the pointer to the object or NULL upon failure.
521 void *ipc_rcu_alloc(int size
)
526 * We prepend the allocation with the rcu struct, and
527 * workqueue if necessary (for vmalloc).
529 if (rcu_use_vmalloc(size
)) {
530 out
= vmalloc(HDRLEN_VMALLOC
+ size
);
534 out
+= HDRLEN_VMALLOC
;
535 container_of(out
, struct ipc_rcu_hdr
, data
)->is_vmalloc
= 1;
537 out
= kmalloc(HDRLEN_KMALLOC
+ size
, GFP_KERNEL
);
541 out
+= HDRLEN_KMALLOC
;
542 container_of(out
, struct ipc_rcu_hdr
, data
)->is_vmalloc
= 0;
545 /* set reference counter no matter what kind of allocation was done */
546 atomic_set(&container_of(out
, struct ipc_rcu_hdr
, data
)->refcount
, 1);
551 int ipc_rcu_getref(void *ptr
)
553 return atomic_inc_not_zero(&container_of(ptr
, struct ipc_rcu_hdr
, data
)->refcount
);
556 static void ipc_do_vfree(struct work_struct
*work
)
558 vfree(container_of(work
, struct ipc_rcu_sched
, work
));
562 * ipc_schedule_free - free ipc + rcu space
563 * @head: RCU callback structure for queued work
565 * Since RCU callback function is called in bh,
566 * we need to defer the vfree to schedule_work().
568 static void ipc_schedule_free(struct rcu_head
*head
)
570 struct ipc_rcu_grace
*grace
;
571 struct ipc_rcu_sched
*sched
;
573 grace
= container_of(head
, struct ipc_rcu_grace
, rcu
);
574 sched
= container_of(&(grace
->data
[0]), struct ipc_rcu_sched
,
577 INIT_WORK(&sched
->work
, ipc_do_vfree
);
578 schedule_work(&sched
->work
);
581 void ipc_rcu_putref(void *ptr
)
583 if (!atomic_dec_and_test(&container_of(ptr
, struct ipc_rcu_hdr
, data
)->refcount
))
586 if (container_of(ptr
, struct ipc_rcu_hdr
, data
)->is_vmalloc
) {
587 call_rcu(&container_of(ptr
, struct ipc_rcu_grace
, data
)->rcu
,
590 kfree_rcu(container_of(ptr
, struct ipc_rcu_grace
, data
), rcu
);
595 * ipcperms - check IPC permissions
597 * @ipcp: IPC permission set
598 * @flag: desired permission set.
600 * Check user, group, other permissions for access
601 * to ipc resources. return 0 if allowed
603 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
606 int ipcperms(struct ipc_namespace
*ns
, struct kern_ipc_perm
*ipcp
, short flag
)
608 kuid_t euid
= current_euid();
609 int requested_mode
, granted_mode
;
612 requested_mode
= (flag
>> 6) | (flag
>> 3) | flag
;
613 granted_mode
= ipcp
->mode
;
614 if (uid_eq(euid
, ipcp
->cuid
) ||
615 uid_eq(euid
, ipcp
->uid
))
617 else if (in_group_p(ipcp
->cgid
) || in_group_p(ipcp
->gid
))
619 /* is there some bit set in requested_mode but not in granted_mode? */
620 if ((requested_mode
& ~granted_mode
& 0007) &&
621 !ns_capable(ns
->user_ns
, CAP_IPC_OWNER
))
624 return security_ipc_permission(ipcp
, flag
);
628 * Functions to convert between the kern_ipc_perm structure and the
629 * old/new ipc_perm structures
633 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
634 * @in: kernel permissions
635 * @out: new style IPC permissions
637 * Turn the kernel object @in into a set of permissions descriptions
638 * for returning to userspace (@out).
642 void kernel_to_ipc64_perm (struct kern_ipc_perm
*in
, struct ipc64_perm
*out
)
645 out
->uid
= from_kuid_munged(current_user_ns(), in
->uid
);
646 out
->gid
= from_kgid_munged(current_user_ns(), in
->gid
);
647 out
->cuid
= from_kuid_munged(current_user_ns(), in
->cuid
);
648 out
->cgid
= from_kgid_munged(current_user_ns(), in
->cgid
);
649 out
->mode
= in
->mode
;
654 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
655 * @in: new style IPC permissions
656 * @out: old style IPC permissions
658 * Turn the new style permissions object @in into a compatibility
659 * object and store it into the @out pointer.
662 void ipc64_perm_to_ipc_perm (struct ipc64_perm
*in
, struct ipc_perm
*out
)
665 SET_UID(out
->uid
, in
->uid
);
666 SET_GID(out
->gid
, in
->gid
);
667 SET_UID(out
->cuid
, in
->cuid
);
668 SET_GID(out
->cgid
, in
->cgid
);
669 out
->mode
= in
->mode
;
675 * @ids: ipc identifier set
676 * @id: ipc id to look for
678 * Look for an id in the ipc ids idr and return associated ipc object.
680 * Call inside the RCU critical section.
681 * The ipc object is *not* locked on exit.
683 struct kern_ipc_perm
*ipc_obtain_object(struct ipc_ids
*ids
, int id
)
685 struct kern_ipc_perm
*out
;
686 int lid
= ipcid_to_idx(id
);
688 out
= idr_find(&ids
->ipcs_idr
, lid
);
690 return ERR_PTR(-EINVAL
);
696 * ipc_lock - Lock an ipc structure without rw_mutex held
697 * @ids: IPC identifier set
698 * @id: ipc id to look for
700 * Look for an id in the ipc ids idr and lock the associated ipc object.
702 * The ipc object is locked on successful exit.
704 struct kern_ipc_perm
*ipc_lock(struct ipc_ids
*ids
, int id
)
706 struct kern_ipc_perm
*out
;
709 out
= ipc_obtain_object(ids
, id
);
713 spin_lock(&out
->lock
);
715 /* ipc_rmid() may have already freed the ID while ipc_lock
716 * was spinning: here verify that the structure is still valid
721 spin_unlock(&out
->lock
);
722 out
= ERR_PTR(-EINVAL
);
729 * ipc_obtain_object_check
730 * @ids: ipc identifier set
731 * @id: ipc id to look for
733 * Similar to ipc_obtain_object() but also checks
734 * the ipc object reference counter.
736 * Call inside the RCU critical section.
737 * The ipc object is *not* locked on exit.
739 struct kern_ipc_perm
*ipc_obtain_object_check(struct ipc_ids
*ids
, int id
)
741 struct kern_ipc_perm
*out
= ipc_obtain_object(ids
, id
);
746 if (ipc_checkid(out
, id
))
747 return ERR_PTR(-EIDRM
);
752 struct kern_ipc_perm
*ipc_lock_check(struct ipc_ids
*ids
, int id
)
754 struct kern_ipc_perm
*out
;
756 out
= ipc_lock(ids
, id
);
760 if (ipc_checkid(out
, id
)) {
762 return ERR_PTR(-EIDRM
);
769 * ipcget - Common sys_*get() code
771 * @ids : IPC identifier set
772 * @ops : operations to be called on ipc object creation, permission checks
774 * @params : the parameters needed by the previous operations.
776 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
778 int ipcget(struct ipc_namespace
*ns
, struct ipc_ids
*ids
,
779 struct ipc_ops
*ops
, struct ipc_params
*params
)
781 if (params
->key
== IPC_PRIVATE
)
782 return ipcget_new(ns
, ids
, ops
, params
);
784 return ipcget_public(ns
, ids
, ops
, params
);
788 * ipc_update_perm - update the permissions of an IPC.
789 * @in: the permission given as input.
790 * @out: the permission of the ipc to set.
792 int ipc_update_perm(struct ipc64_perm
*in
, struct kern_ipc_perm
*out
)
794 kuid_t uid
= make_kuid(current_user_ns(), in
->uid
);
795 kgid_t gid
= make_kgid(current_user_ns(), in
->gid
);
796 if (!uid_valid(uid
) || !gid_valid(gid
))
801 out
->mode
= (out
->mode
& ~S_IRWXUGO
)
802 | (in
->mode
& S_IRWXUGO
);
808 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
809 * @ns: the ipc namespace
810 * @ids: the table of ids where to look for the ipc
811 * @id: the id of the ipc to retrieve
812 * @cmd: the cmd to check
813 * @perm: the permission to set
814 * @extra_perm: one extra permission parameter used by msq
816 * This function does some common audit and permissions check for some IPC_XXX
817 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
818 * It must be called without any lock held and
819 * - retrieves the ipc with the given id in the given table.
820 * - performs some audit and permission check, depending on the given cmd
821 * - returns the ipc with both ipc and rw_mutex locks held in case of success
822 * or an err-code without any lock held otherwise.
824 struct kern_ipc_perm
*ipcctl_pre_down(struct ipc_namespace
*ns
,
825 struct ipc_ids
*ids
, int id
, int cmd
,
826 struct ipc64_perm
*perm
, int extra_perm
)
828 struct kern_ipc_perm
*ipcp
;
830 ipcp
= ipcctl_pre_down_nolock(ns
, ids
, id
, cmd
, perm
, extra_perm
);
834 spin_lock(&ipcp
->lock
);
839 struct kern_ipc_perm
*ipcctl_pre_down_nolock(struct ipc_namespace
*ns
,
840 struct ipc_ids
*ids
, int id
, int cmd
,
841 struct ipc64_perm
*perm
, int extra_perm
)
845 struct kern_ipc_perm
*ipcp
;
847 down_write(&ids
->rw_mutex
);
850 ipcp
= ipc_obtain_object_check(ids
, id
);
858 audit_ipc_set_perm(extra_perm
, perm
->uid
,
859 perm
->gid
, perm
->mode
);
861 euid
= current_euid();
862 if (uid_eq(euid
, ipcp
->cuid
) || uid_eq(euid
, ipcp
->uid
) ||
863 ns_capable(ns
->user_ns
, CAP_SYS_ADMIN
))
868 * Unsuccessful lookup, unlock and return
869 * the corresponding error.
872 up_write(&ids
->rw_mutex
);
877 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
881 * ipc_parse_version - IPC call version
882 * @cmd: pointer to command
884 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
885 * The @cmd value is turned from an encoding command and version into
886 * just the command code.
889 int ipc_parse_version (int *cmd
)
899 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
901 #ifdef CONFIG_PROC_FS
902 struct ipc_proc_iter
{
903 struct ipc_namespace
*ns
;
904 struct ipc_proc_iface
*iface
;
908 * This routine locks the ipc structure found at least at position pos.
910 static struct kern_ipc_perm
*sysvipc_find_ipc(struct ipc_ids
*ids
, loff_t pos
,
913 struct kern_ipc_perm
*ipc
;
917 for (id
= 0; id
< pos
&& total
< ids
->in_use
; id
++) {
918 ipc
= idr_find(&ids
->ipcs_idr
, id
);
923 if (total
>= ids
->in_use
)
926 for ( ; pos
< IPCMNI
; pos
++) {
927 ipc
= idr_find(&ids
->ipcs_idr
, pos
);
930 ipc_lock_by_ptr(ipc
);
935 /* Out of range - return NULL to terminate iteration */
939 static void *sysvipc_proc_next(struct seq_file
*s
, void *it
, loff_t
*pos
)
941 struct ipc_proc_iter
*iter
= s
->private;
942 struct ipc_proc_iface
*iface
= iter
->iface
;
943 struct kern_ipc_perm
*ipc
= it
;
945 /* If we had an ipc id locked before, unlock it */
946 if (ipc
&& ipc
!= SEQ_START_TOKEN
)
949 return sysvipc_find_ipc(&iter
->ns
->ids
[iface
->ids
], *pos
, pos
);
953 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
954 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
956 static void *sysvipc_proc_start(struct seq_file
*s
, loff_t
*pos
)
958 struct ipc_proc_iter
*iter
= s
->private;
959 struct ipc_proc_iface
*iface
= iter
->iface
;
962 ids
= &iter
->ns
->ids
[iface
->ids
];
965 * Take the lock - this will be released by the corresponding
968 down_read(&ids
->rw_mutex
);
970 /* pos < 0 is invalid */
974 /* pos == 0 means header */
976 return SEQ_START_TOKEN
;
978 /* Find the (pos-1)th ipc */
979 return sysvipc_find_ipc(ids
, *pos
- 1, pos
);
982 static void sysvipc_proc_stop(struct seq_file
*s
, void *it
)
984 struct kern_ipc_perm
*ipc
= it
;
985 struct ipc_proc_iter
*iter
= s
->private;
986 struct ipc_proc_iface
*iface
= iter
->iface
;
989 /* If we had a locked structure, release it */
990 if (ipc
&& ipc
!= SEQ_START_TOKEN
)
993 ids
= &iter
->ns
->ids
[iface
->ids
];
994 /* Release the lock we took in start() */
995 up_read(&ids
->rw_mutex
);
998 static int sysvipc_proc_show(struct seq_file
*s
, void *it
)
1000 struct ipc_proc_iter
*iter
= s
->private;
1001 struct ipc_proc_iface
*iface
= iter
->iface
;
1003 if (it
== SEQ_START_TOKEN
)
1004 return seq_puts(s
, iface
->header
);
1006 return iface
->show(s
, it
);
1009 static const struct seq_operations sysvipc_proc_seqops
= {
1010 .start
= sysvipc_proc_start
,
1011 .stop
= sysvipc_proc_stop
,
1012 .next
= sysvipc_proc_next
,
1013 .show
= sysvipc_proc_show
,
1016 static int sysvipc_proc_open(struct inode
*inode
, struct file
*file
)
1019 struct seq_file
*seq
;
1020 struct ipc_proc_iter
*iter
;
1023 iter
= kmalloc(sizeof(*iter
), GFP_KERNEL
);
1027 ret
= seq_open(file
, &sysvipc_proc_seqops
);
1031 seq
= file
->private_data
;
1032 seq
->private = iter
;
1034 iter
->iface
= PDE(inode
)->data
;
1035 iter
->ns
= get_ipc_ns(current
->nsproxy
->ipc_ns
);
1043 static int sysvipc_proc_release(struct inode
*inode
, struct file
*file
)
1045 struct seq_file
*seq
= file
->private_data
;
1046 struct ipc_proc_iter
*iter
= seq
->private;
1047 put_ipc_ns(iter
->ns
);
1048 return seq_release_private(inode
, file
);
1051 static const struct file_operations sysvipc_proc_fops
= {
1052 .open
= sysvipc_proc_open
,
1054 .llseek
= seq_lseek
,
1055 .release
= sysvipc_proc_release
,
1057 #endif /* CONFIG_PROC_FS */