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/smp_lock.h>
25 #include <linux/vmalloc.h>
26 #include <linux/slab.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>
37 #include <asm/unistd.h>
41 struct ipc_proc_iface
{
45 int (*show
)(struct seq_file
*, void *);
48 struct ipc_namespace init_ipc_ns
= {
50 .refcount
= ATOMIC_INIT(2),
55 static struct ipc_namespace
*clone_ipc_ns(struct ipc_namespace
*old_ns
)
58 struct ipc_namespace
*ns
;
61 ns
= kmalloc(sizeof(struct ipc_namespace
), GFP_KERNEL
);
65 err
= sem_init_ns(ns
);
68 err
= msg_init_ns(ns
);
71 err
= shm_init_ns(ns
);
88 struct ipc_namespace
*copy_ipcs(unsigned long flags
, struct ipc_namespace
*ns
)
90 struct ipc_namespace
*new_ns
;
95 if (!(flags
& CLONE_NEWIPC
))
98 new_ns
= clone_ipc_ns(ns
);
104 void free_ipc_ns(struct kref
*kref
)
106 struct ipc_namespace
*ns
;
108 ns
= container_of(kref
, struct ipc_namespace
, kref
);
115 struct ipc_namespace
*copy_ipcs(unsigned long flags
, struct ipc_namespace
*ns
)
117 if (flags
& CLONE_NEWIPC
)
118 return ERR_PTR(-EINVAL
);
124 * ipc_init - initialise IPC subsystem
126 * The various system5 IPC resources (semaphores, messages and shared
127 * memory) are initialised
130 static int __init
ipc_init(void)
137 __initcall(ipc_init
);
140 * ipc_init_ids - initialise IPC identifiers
141 * @ids: Identifier set
142 * @size: Number of identifiers
144 * Given a size for the ipc identifier range (limited below IPCMNI)
145 * set up the sequence range to use then allocate and initialise the
149 void __ipc_init
ipc_init_ids(struct ipc_ids
* ids
, int size
)
153 mutex_init(&ids
->mutex
);
161 int seq_limit
= INT_MAX
/SEQ_MULTIPLIER
;
162 if(seq_limit
> USHRT_MAX
)
163 ids
->seq_max
= USHRT_MAX
;
165 ids
->seq_max
= seq_limit
;
168 ids
->entries
= ipc_rcu_alloc(sizeof(struct kern_ipc_perm
*)*size
+
169 sizeof(struct ipc_id_ary
));
171 if(ids
->entries
== NULL
) {
172 printk(KERN_ERR
"ipc_init_ids() failed, ipc service disabled.\n");
174 ids
->entries
= &ids
->nullentry
;
176 ids
->entries
->size
= size
;
178 ids
->entries
->p
[i
] = NULL
;
181 #ifdef CONFIG_PROC_FS
182 static const struct file_operations sysvipc_proc_fops
;
184 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
185 * @path: Path in procfs
186 * @header: Banner to be printed at the beginning of the file.
187 * @ids: ipc id table to iterate.
188 * @show: show routine.
190 void __init
ipc_init_proc_interface(const char *path
, const char *header
,
191 int ids
, int (*show
)(struct seq_file
*, void *))
193 struct proc_dir_entry
*pde
;
194 struct ipc_proc_iface
*iface
;
196 iface
= kmalloc(sizeof(*iface
), GFP_KERNEL
);
200 iface
->header
= header
;
204 pde
= create_proc_entry(path
,
205 S_IRUGO
, /* world readable */
206 NULL
/* parent dir */);
209 pde
->proc_fops
= &sysvipc_proc_fops
;
217 * ipc_findkey - find a key in an ipc identifier set
218 * @ids: Identifier set
219 * @key: The key to find
221 * Requires ipc_ids.mutex locked.
222 * Returns the identifier if found or -1 if not.
225 int ipc_findkey(struct ipc_ids
* ids
, key_t key
)
228 struct kern_ipc_perm
* p
;
229 int max_id
= ids
->max_id
;
232 * rcu_dereference() is not needed here
233 * since ipc_ids.mutex is held
235 for (id
= 0; id
<= max_id
; id
++) {
236 p
= ids
->entries
->p
[id
];
246 * Requires ipc_ids.mutex locked
248 static int grow_ary(struct ipc_ids
* ids
, int newsize
)
250 struct ipc_id_ary
* new;
251 struct ipc_id_ary
* old
;
253 int size
= ids
->entries
->size
;
260 new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm
*)*newsize
+
261 sizeof(struct ipc_id_ary
));
265 memcpy(new->p
, ids
->entries
->p
, sizeof(struct kern_ipc_perm
*)*size
);
266 for(i
=size
;i
<newsize
;i
++) {
272 * Use rcu_assign_pointer() to make sure the memcpyed contents
273 * of the new array are visible before the new array becomes visible.
275 rcu_assign_pointer(ids
->entries
, new);
277 __ipc_fini_ids(ids
, old
);
282 * ipc_addid - add an IPC identifier
283 * @ids: IPC identifier set
284 * @new: new IPC permission set
285 * @size: new size limit for the id array
287 * Add an entry 'new' to the IPC arrays. The permissions object is
288 * initialised and the first free entry is set up and the id assigned
289 * is returned. The list is returned in a locked state on success.
290 * On failure the list is not locked and -1 is returned.
292 * Called with ipc_ids.mutex held.
295 int ipc_addid(struct ipc_ids
* ids
, struct kern_ipc_perm
* new, int size
)
299 size
= grow_ary(ids
,size
);
302 * rcu_dereference()() is not needed here since
303 * ipc_ids.mutex is held
305 for (id
= 0; id
< size
; id
++) {
306 if(ids
->entries
->p
[id
] == NULL
)
312 if (id
> ids
->max_id
)
315 new->cuid
= new->uid
= current
->euid
;
316 new->gid
= new->cgid
= current
->egid
;
318 new->seq
= ids
->seq
++;
319 if(ids
->seq
> ids
->seq_max
)
322 spin_lock_init(&new->lock
);
325 spin_lock(&new->lock
);
326 ids
->entries
->p
[id
] = new;
331 * ipc_rmid - remove an IPC identifier
332 * @ids: identifier set
333 * @id: Identifier to remove
335 * The identifier must be valid, and in use. The kernel will panic if
336 * fed an invalid identifier. The entry is removed and internal
337 * variables recomputed. The object associated with the identifier
339 * ipc_ids.mutex and the spinlock for this ID is hold before this function
340 * is called, and remain locked on the exit.
343 struct kern_ipc_perm
* ipc_rmid(struct ipc_ids
* ids
, int id
)
345 struct kern_ipc_perm
* p
;
346 int lid
= id
% SEQ_MULTIPLIER
;
347 BUG_ON(lid
>= ids
->entries
->size
);
350 * do not need a rcu_dereference()() here to force ordering
351 * on Alpha, since the ipc_ids.mutex is held.
353 p
= ids
->entries
->p
[lid
];
354 ids
->entries
->p
[lid
] = NULL
;
358 if (lid
== ids
->max_id
) {
363 } while (ids
->entries
->p
[lid
] == NULL
);
371 * ipc_alloc - allocate ipc space
372 * @size: size desired
374 * Allocate memory from the appropriate pools and return a pointer to it.
375 * NULL is returned if the allocation fails
378 void* ipc_alloc(int size
)
384 out
= kmalloc(size
, GFP_KERNEL
);
389 * ipc_free - free ipc space
390 * @ptr: pointer returned by ipc_alloc
391 * @size: size of block
393 * Free a block created with ipc_alloc(). The caller must know the size
394 * used in the allocation call.
397 void ipc_free(void* ptr
, int size
)
407 * There are three headers that are prepended to the actual allocation:
408 * - during use: ipc_rcu_hdr.
409 * - during the rcu grace period: ipc_rcu_grace.
410 * - [only if vmalloc]: ipc_rcu_sched.
411 * Their lifetime doesn't overlap, thus the headers share the same memory.
412 * Unlike a normal union, they are right-aligned, thus some container_of
413 * forward/backward casting is necessary:
426 /* "void *" makes sure alignment of following data is sane. */
432 struct work_struct work
;
433 /* "void *" makes sure alignment of following data is sane. */
437 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
438 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
439 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
440 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
442 static inline int rcu_use_vmalloc(int size
)
444 /* Too big for a single page? */
445 if (HDRLEN_KMALLOC
+ size
> PAGE_SIZE
)
451 * ipc_rcu_alloc - allocate ipc and rcu space
452 * @size: size desired
454 * Allocate memory for the rcu header structure + the object.
455 * Returns the pointer to the object.
456 * NULL is returned if the allocation fails.
459 void* ipc_rcu_alloc(int size
)
463 * We prepend the allocation with the rcu struct, and
464 * workqueue if necessary (for vmalloc).
466 if (rcu_use_vmalloc(size
)) {
467 out
= vmalloc(HDRLEN_VMALLOC
+ size
);
469 out
+= HDRLEN_VMALLOC
;
470 container_of(out
, struct ipc_rcu_hdr
, data
)->is_vmalloc
= 1;
471 container_of(out
, struct ipc_rcu_hdr
, data
)->refcount
= 1;
474 out
= kmalloc(HDRLEN_KMALLOC
+ size
, GFP_KERNEL
);
476 out
+= HDRLEN_KMALLOC
;
477 container_of(out
, struct ipc_rcu_hdr
, data
)->is_vmalloc
= 0;
478 container_of(out
, struct ipc_rcu_hdr
, data
)->refcount
= 1;
485 void ipc_rcu_getref(void *ptr
)
487 container_of(ptr
, struct ipc_rcu_hdr
, data
)->refcount
++;
490 static void ipc_do_vfree(struct work_struct
*work
)
492 vfree(container_of(work
, struct ipc_rcu_sched
, work
));
496 * ipc_schedule_free - free ipc + rcu space
497 * @head: RCU callback structure for queued work
499 * Since RCU callback function is called in bh,
500 * we need to defer the vfree to schedule_work().
502 static void ipc_schedule_free(struct rcu_head
*head
)
504 struct ipc_rcu_grace
*grace
=
505 container_of(head
, struct ipc_rcu_grace
, rcu
);
506 struct ipc_rcu_sched
*sched
=
507 container_of(&(grace
->data
[0]), struct ipc_rcu_sched
, data
[0]);
509 INIT_WORK(&sched
->work
, ipc_do_vfree
);
510 schedule_work(&sched
->work
);
514 * ipc_immediate_free - free ipc + rcu space
515 * @head: RCU callback structure that contains pointer to be freed
517 * Free from the RCU callback context.
519 static void ipc_immediate_free(struct rcu_head
*head
)
521 struct ipc_rcu_grace
*free
=
522 container_of(head
, struct ipc_rcu_grace
, rcu
);
526 void ipc_rcu_putref(void *ptr
)
528 if (--container_of(ptr
, struct ipc_rcu_hdr
, data
)->refcount
> 0)
531 if (container_of(ptr
, struct ipc_rcu_hdr
, data
)->is_vmalloc
) {
532 call_rcu(&container_of(ptr
, struct ipc_rcu_grace
, data
)->rcu
,
535 call_rcu(&container_of(ptr
, struct ipc_rcu_grace
, data
)->rcu
,
541 * ipcperms - check IPC permissions
542 * @ipcp: IPC permission set
543 * @flag: desired permission set.
545 * Check user, group, other permissions for access
546 * to ipc resources. return 0 if allowed
549 int ipcperms (struct kern_ipc_perm
*ipcp
, short flag
)
550 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
551 int requested_mode
, granted_mode
, err
;
553 if (unlikely((err
= audit_ipc_obj(ipcp
))))
555 requested_mode
= (flag
>> 6) | (flag
>> 3) | flag
;
556 granted_mode
= ipcp
->mode
;
557 if (current
->euid
== ipcp
->cuid
|| current
->euid
== ipcp
->uid
)
559 else if (in_group_p(ipcp
->cgid
) || in_group_p(ipcp
->gid
))
561 /* is there some bit set in requested_mode but not in granted_mode? */
562 if ((requested_mode
& ~granted_mode
& 0007) &&
563 !capable(CAP_IPC_OWNER
))
566 return security_ipc_permission(ipcp
, flag
);
570 * Functions to convert between the kern_ipc_perm structure and the
571 * old/new ipc_perm structures
575 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
576 * @in: kernel permissions
577 * @out: new style IPC permissions
579 * Turn the kernel object @in into a set of permissions descriptions
580 * for returning to userspace (@out).
584 void kernel_to_ipc64_perm (struct kern_ipc_perm
*in
, struct ipc64_perm
*out
)
589 out
->cuid
= in
->cuid
;
590 out
->cgid
= in
->cgid
;
591 out
->mode
= in
->mode
;
596 * ipc64_perm_to_ipc_perm - convert old ipc permissions to new
597 * @in: new style IPC permissions
598 * @out: old style IPC permissions
600 * Turn the new style permissions object @in into a compatibility
601 * object and store it into the @out pointer.
604 void ipc64_perm_to_ipc_perm (struct ipc64_perm
*in
, struct ipc_perm
*out
)
607 SET_UID(out
->uid
, in
->uid
);
608 SET_GID(out
->gid
, in
->gid
);
609 SET_UID(out
->cuid
, in
->cuid
);
610 SET_GID(out
->cgid
, in
->cgid
);
611 out
->mode
= in
->mode
;
616 * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
617 * is called with shm_ids.mutex locked. Since grow_ary() is also called with
618 * shm_ids.mutex down(for Shared Memory), there is no need to add read
619 * barriers here to gurantee the writes in grow_ary() are seen in order
622 * However ipc_get() itself does not necessary require ipc_ids.mutex down. So
623 * if in the future ipc_get() is used by other places without ipc_ids.mutex
624 * down, then ipc_get() needs read memery barriers as ipc_lock() does.
626 struct kern_ipc_perm
* ipc_get(struct ipc_ids
* ids
, int id
)
628 struct kern_ipc_perm
* out
;
629 int lid
= id
% SEQ_MULTIPLIER
;
630 if(lid
>= ids
->entries
->size
)
632 out
= ids
->entries
->p
[lid
];
636 struct kern_ipc_perm
* ipc_lock(struct ipc_ids
* ids
, int id
)
638 struct kern_ipc_perm
* out
;
639 int lid
= id
% SEQ_MULTIPLIER
;
640 struct ipc_id_ary
* entries
;
643 entries
= rcu_dereference(ids
->entries
);
644 if(lid
>= entries
->size
) {
648 out
= entries
->p
[lid
];
653 spin_lock(&out
->lock
);
655 /* ipc_rmid() may have already freed the ID while ipc_lock
656 * was spinning: here verify that the structure is still valid
659 spin_unlock(&out
->lock
);
666 void ipc_lock_by_ptr(struct kern_ipc_perm
*perm
)
669 spin_lock(&perm
->lock
);
672 void ipc_unlock(struct kern_ipc_perm
* perm
)
674 spin_unlock(&perm
->lock
);
678 int ipc_buildid(struct ipc_ids
* ids
, int id
, int seq
)
680 return SEQ_MULTIPLIER
*seq
+ id
;
683 int ipc_checkid(struct ipc_ids
* ids
, struct kern_ipc_perm
* ipcp
, int uid
)
685 if(uid
/SEQ_MULTIPLIER
!= ipcp
->seq
)
690 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
694 * ipc_parse_version - IPC call version
695 * @cmd: pointer to command
697 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
698 * The @cmd value is turned from an encoding command and version into
699 * just the command code.
702 int ipc_parse_version (int *cmd
)
712 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
714 #ifdef CONFIG_PROC_FS
715 struct ipc_proc_iter
{
716 struct ipc_namespace
*ns
;
717 struct ipc_proc_iface
*iface
;
720 static void *sysvipc_proc_next(struct seq_file
*s
, void *it
, loff_t
*pos
)
722 struct ipc_proc_iter
*iter
= s
->private;
723 struct ipc_proc_iface
*iface
= iter
->iface
;
724 struct kern_ipc_perm
*ipc
= it
;
728 ids
= iter
->ns
->ids
[iface
->ids
];
730 /* If we had an ipc id locked before, unlock it */
731 if (ipc
&& ipc
!= SEQ_START_TOKEN
)
735 * p = *pos - 1 (because id 0 starts at position 1)
736 * + 1 (because we increment the position by one)
738 for (p
= *pos
; p
<= ids
->max_id
; p
++) {
739 if ((ipc
= ipc_lock(ids
, p
)) != NULL
) {
745 /* Out of range - return NULL to terminate iteration */
750 * File positions: pos 0 -> header, pos n -> ipc id + 1.
751 * SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.
753 static void *sysvipc_proc_start(struct seq_file
*s
, loff_t
*pos
)
755 struct ipc_proc_iter
*iter
= s
->private;
756 struct ipc_proc_iface
*iface
= iter
->iface
;
757 struct kern_ipc_perm
*ipc
;
761 ids
= iter
->ns
->ids
[iface
->ids
];
764 * Take the lock - this will be released by the corresponding
767 mutex_lock(&ids
->mutex
);
769 /* pos < 0 is invalid */
773 /* pos == 0 means header */
775 return SEQ_START_TOKEN
;
777 /* Find the (pos-1)th ipc */
778 for (p
= *pos
- 1; p
<= ids
->max_id
; p
++) {
779 if ((ipc
= ipc_lock(ids
, p
)) != NULL
) {
787 static void sysvipc_proc_stop(struct seq_file
*s
, void *it
)
789 struct kern_ipc_perm
*ipc
= it
;
790 struct ipc_proc_iter
*iter
= s
->private;
791 struct ipc_proc_iface
*iface
= iter
->iface
;
794 /* If we had a locked segment, release it */
795 if (ipc
&& ipc
!= SEQ_START_TOKEN
)
798 ids
= iter
->ns
->ids
[iface
->ids
];
799 /* Release the lock we took in start() */
800 mutex_unlock(&ids
->mutex
);
803 static int sysvipc_proc_show(struct seq_file
*s
, void *it
)
805 struct ipc_proc_iter
*iter
= s
->private;
806 struct ipc_proc_iface
*iface
= iter
->iface
;
808 if (it
== SEQ_START_TOKEN
)
809 return seq_puts(s
, iface
->header
);
811 return iface
->show(s
, it
);
814 static struct seq_operations sysvipc_proc_seqops
= {
815 .start
= sysvipc_proc_start
,
816 .stop
= sysvipc_proc_stop
,
817 .next
= sysvipc_proc_next
,
818 .show
= sysvipc_proc_show
,
821 static int sysvipc_proc_open(struct inode
*inode
, struct file
*file
)
824 struct seq_file
*seq
;
825 struct ipc_proc_iter
*iter
;
828 iter
= kmalloc(sizeof(*iter
), GFP_KERNEL
);
832 ret
= seq_open(file
, &sysvipc_proc_seqops
);
836 seq
= file
->private_data
;
839 iter
->iface
= PDE(inode
)->data
;
840 iter
->ns
= get_ipc_ns(current
->nsproxy
->ipc_ns
);
848 static int sysvipc_proc_release(struct inode
*inode
, struct file
*file
)
850 struct seq_file
*seq
= file
->private_data
;
851 struct ipc_proc_iter
*iter
= seq
->private;
852 put_ipc_ns(iter
->ns
);
853 return seq_release_private(inode
, file
);
856 static const struct file_operations sysvipc_proc_fops
= {
857 .open
= sysvipc_proc_open
,
860 .release
= sysvipc_proc_release
,
862 #endif /* CONFIG_PROC_FS */