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 <manfreds@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>
15 #include <linux/config.h>
17 #include <linux/shm.h>
18 #include <linux/init.h>
19 #include <linux/msg.h>
20 #include <linux/smp_lock.h>
21 #include <linux/vmalloc.h>
22 #include <linux/slab.h>
23 #include <linux/highuid.h>
24 #include <linux/security.h>
25 #include <linux/rcupdate.h>
26 #include <linux/workqueue.h>
28 #include <asm/unistd.h>
33 * ipc_init - initialise IPC subsystem
35 * The various system5 IPC resources (semaphores, messages and shared
36 * memory are initialised
39 static int __init
ipc_init(void)
49 * ipc_init_ids - initialise IPC identifiers
50 * @ids: Identifier set
51 * @size: Number of identifiers
53 * Given a size for the ipc identifier range (limited below IPCMNI)
54 * set up the sequence range to use then allocate and initialise the
58 void __init
ipc_init_ids(struct ipc_ids
* ids
, int size
)
61 sema_init(&ids
->sem
,1);
69 int seq_limit
= INT_MAX
/SEQ_MULTIPLIER
;
70 if(seq_limit
> USHRT_MAX
)
71 ids
->seq_max
= USHRT_MAX
;
73 ids
->seq_max
= seq_limit
;
76 ids
->entries
= ipc_rcu_alloc(sizeof(struct kern_ipc_perm
*)*size
+
77 sizeof(struct ipc_id_ary
));
79 if(ids
->entries
== NULL
) {
80 printk(KERN_ERR
"ipc_init_ids() failed, ipc service disabled.\n");
82 ids
->entries
= &ids
->nullentry
;
84 ids
->entries
->size
= size
;
86 ids
->entries
->p
[i
] = NULL
;
90 * ipc_findkey - find a key in an ipc identifier set
91 * @ids: Identifier set
92 * @key: The key to find
94 * Requires ipc_ids.sem locked.
95 * Returns the identifier if found or -1 if not.
98 int ipc_findkey(struct ipc_ids
* ids
, key_t key
)
101 struct kern_ipc_perm
* p
;
102 int max_id
= ids
->max_id
;
105 * rcu_dereference() is not needed here
106 * since ipc_ids.sem is held
108 for (id
= 0; id
<= max_id
; id
++) {
109 p
= ids
->entries
->p
[id
];
119 * Requires ipc_ids.sem locked
121 static int grow_ary(struct ipc_ids
* ids
, int newsize
)
123 struct ipc_id_ary
* new;
124 struct ipc_id_ary
* old
;
126 int size
= ids
->entries
->size
;
133 new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm
*)*newsize
+
134 sizeof(struct ipc_id_ary
));
138 memcpy(new->p
, ids
->entries
->p
, sizeof(struct kern_ipc_perm
*)*size
+
139 sizeof(struct ipc_id_ary
));
140 for(i
=size
;i
<newsize
;i
++) {
146 * Use rcu_assign_pointer() to make sure the memcpyed contents
147 * of the new array are visible before the new array becomes visible.
149 rcu_assign_pointer(ids
->entries
, new);
156 * ipc_addid - add an IPC identifier
157 * @ids: IPC identifier set
158 * @new: new IPC permission set
159 * @size: new size limit for the id array
161 * Add an entry 'new' to the IPC arrays. The permissions object is
162 * initialised and the first free entry is set up and the id assigned
163 * is returned. The list is returned in a locked state on success.
164 * On failure the list is not locked and -1 is returned.
166 * Called with ipc_ids.sem held.
169 int ipc_addid(struct ipc_ids
* ids
, struct kern_ipc_perm
* new, int size
)
173 size
= grow_ary(ids
,size
);
176 * rcu_dereference()() is not needed here since
177 * ipc_ids.sem is held
179 for (id
= 0; id
< size
; id
++) {
180 if(ids
->entries
->p
[id
] == NULL
)
186 if (id
> ids
->max_id
)
189 new->cuid
= new->uid
= current
->euid
;
190 new->gid
= new->cgid
= current
->egid
;
192 new->seq
= ids
->seq
++;
193 if(ids
->seq
> ids
->seq_max
)
196 spin_lock_init(&new->lock
);
199 spin_lock(&new->lock
);
200 ids
->entries
->p
[id
] = new;
205 * ipc_rmid - remove an IPC identifier
206 * @ids: identifier set
207 * @id: Identifier to remove
209 * The identifier must be valid, and in use. The kernel will panic if
210 * fed an invalid identifier. The entry is removed and internal
211 * variables recomputed. The object associated with the identifier
213 * ipc_ids.sem and the spinlock for this ID is hold before this function
214 * is called, and remain locked on the exit.
217 struct kern_ipc_perm
* ipc_rmid(struct ipc_ids
* ids
, int id
)
219 struct kern_ipc_perm
* p
;
220 int lid
= id
% SEQ_MULTIPLIER
;
221 if(lid
>= ids
->entries
->size
)
225 * do not need a rcu_dereference()() here to force ordering
226 * on Alpha, since the ipc_ids.sem is held.
228 p
= ids
->entries
->p
[lid
];
229 ids
->entries
->p
[lid
] = NULL
;
234 if (lid
== ids
->max_id
) {
239 } while (ids
->entries
->p
[lid
] == NULL
);
247 * ipc_alloc - allocate ipc space
248 * @size: size desired
250 * Allocate memory from the appropriate pools and return a pointer to it.
251 * NULL is returned if the allocation fails
254 void* ipc_alloc(int size
)
260 out
= kmalloc(size
, GFP_KERNEL
);
265 * ipc_free - free ipc space
266 * @ptr: pointer returned by ipc_alloc
267 * @size: size of block
269 * Free a block created with ipc_alloc. The caller must know the size
270 * used in the allocation call.
273 void ipc_free(void* ptr
, int size
)
283 * There are three headers that are prepended to the actual allocation:
284 * - during use: ipc_rcu_hdr.
285 * - during the rcu grace period: ipc_rcu_grace.
286 * - [only if vmalloc]: ipc_rcu_sched.
287 * Their lifetime doesn't overlap, thus the headers share the same memory.
288 * Unlike a normal union, they are right-aligned, thus some container_of
289 * forward/backward casting is necessary:
302 /* "void *" makes sure alignment of following data is sane. */
308 struct work_struct work
;
309 /* "void *" makes sure alignment of following data is sane. */
313 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
314 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
315 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
316 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
318 static inline int rcu_use_vmalloc(int size
)
320 /* Too big for a single page? */
321 if (HDRLEN_KMALLOC
+ size
> PAGE_SIZE
)
327 * ipc_rcu_alloc - allocate ipc and rcu space
328 * @size: size desired
330 * Allocate memory for the rcu header structure + the object.
331 * Returns the pointer to the object.
332 * NULL is returned if the allocation fails.
335 void* ipc_rcu_alloc(int size
)
339 * We prepend the allocation with the rcu struct, and
340 * workqueue if necessary (for vmalloc).
342 if (rcu_use_vmalloc(size
)) {
343 out
= vmalloc(HDRLEN_VMALLOC
+ size
);
345 out
+= HDRLEN_VMALLOC
;
346 container_of(out
, struct ipc_rcu_hdr
, data
)->is_vmalloc
= 1;
347 container_of(out
, struct ipc_rcu_hdr
, data
)->refcount
= 1;
350 out
= kmalloc(HDRLEN_KMALLOC
+ size
, GFP_KERNEL
);
352 out
+= HDRLEN_KMALLOC
;
353 container_of(out
, struct ipc_rcu_hdr
, data
)->is_vmalloc
= 0;
354 container_of(out
, struct ipc_rcu_hdr
, data
)->refcount
= 1;
361 void ipc_rcu_getref(void *ptr
)
363 container_of(ptr
, struct ipc_rcu_hdr
, data
)->refcount
++;
367 * ipc_schedule_free - free ipc + rcu space
369 * Since RCU callback function is called in bh,
370 * we need to defer the vfree to schedule_work
372 static void ipc_schedule_free(struct rcu_head
*head
)
374 struct ipc_rcu_grace
*grace
=
375 container_of(head
, struct ipc_rcu_grace
, rcu
);
376 struct ipc_rcu_sched
*sched
=
377 container_of(&(grace
->data
[0]), struct ipc_rcu_sched
, data
[0]);
379 INIT_WORK(&sched
->work
, vfree
, sched
);
380 schedule_work(&sched
->work
);
384 * ipc_immediate_free - free ipc + rcu space
386 * Free from the RCU callback context
389 static void ipc_immediate_free(struct rcu_head
*head
)
391 struct ipc_rcu_grace
*free
=
392 container_of(head
, struct ipc_rcu_grace
, rcu
);
396 void ipc_rcu_putref(void *ptr
)
398 if (--container_of(ptr
, struct ipc_rcu_hdr
, data
)->refcount
> 0)
401 if (container_of(ptr
, struct ipc_rcu_hdr
, data
)->is_vmalloc
) {
402 call_rcu(&container_of(ptr
, struct ipc_rcu_grace
, data
)->rcu
,
405 call_rcu(&container_of(ptr
, struct ipc_rcu_grace
, data
)->rcu
,
411 * ipcperms - check IPC permissions
412 * @ipcp: IPC permission set
413 * @flag: desired permission set.
415 * Check user, group, other permissions for access
416 * to ipc resources. return 0 if allowed
419 int ipcperms (struct kern_ipc_perm
*ipcp
, short flag
)
420 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
421 int requested_mode
, granted_mode
;
423 requested_mode
= (flag
>> 6) | (flag
>> 3) | flag
;
424 granted_mode
= ipcp
->mode
;
425 if (current
->euid
== ipcp
->cuid
|| current
->euid
== ipcp
->uid
)
427 else if (in_group_p(ipcp
->cgid
) || in_group_p(ipcp
->gid
))
429 /* is there some bit set in requested_mode but not in granted_mode? */
430 if ((requested_mode
& ~granted_mode
& 0007) &&
431 !capable(CAP_IPC_OWNER
))
434 return security_ipc_permission(ipcp
, flag
);
438 * Functions to convert between the kern_ipc_perm structure and the
439 * old/new ipc_perm structures
443 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
444 * @in: kernel permissions
445 * @out: new style IPC permissions
447 * Turn the kernel object 'in' into a set of permissions descriptions
448 * for returning to userspace (out).
452 void kernel_to_ipc64_perm (struct kern_ipc_perm
*in
, struct ipc64_perm
*out
)
457 out
->cuid
= in
->cuid
;
458 out
->cgid
= in
->cgid
;
459 out
->mode
= in
->mode
;
464 * ipc64_perm_to_ipc_perm - convert old ipc permissions to new
465 * @in: new style IPC permissions
466 * @out: old style IPC permissions
468 * Turn the new style permissions object in into a compatibility
469 * object and store it into the 'out' pointer.
472 void ipc64_perm_to_ipc_perm (struct ipc64_perm
*in
, struct ipc_perm
*out
)
475 SET_UID(out
->uid
, in
->uid
);
476 SET_GID(out
->gid
, in
->gid
);
477 SET_UID(out
->cuid
, in
->cuid
);
478 SET_GID(out
->cgid
, in
->cgid
);
479 out
->mode
= in
->mode
;
484 * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
485 * is called with shm_ids.sem locked. Since grow_ary() is also called with
486 * shm_ids.sem down(for Shared Memory), there is no need to add read
487 * barriers here to gurantee the writes in grow_ary() are seen in order
490 * However ipc_get() itself does not necessary require ipc_ids.sem down. So
491 * if in the future ipc_get() is used by other places without ipc_ids.sem
492 * down, then ipc_get() needs read memery barriers as ipc_lock() does.
494 struct kern_ipc_perm
* ipc_get(struct ipc_ids
* ids
, int id
)
496 struct kern_ipc_perm
* out
;
497 int lid
= id
% SEQ_MULTIPLIER
;
498 if(lid
>= ids
->entries
->size
)
500 out
= ids
->entries
->p
[lid
];
504 struct kern_ipc_perm
* ipc_lock(struct ipc_ids
* ids
, int id
)
506 struct kern_ipc_perm
* out
;
507 int lid
= id
% SEQ_MULTIPLIER
;
508 struct ipc_id_ary
* entries
;
511 entries
= rcu_dereference(ids
->entries
);
512 if(lid
>= entries
->size
) {
516 out
= entries
->p
[lid
];
521 spin_lock(&out
->lock
);
523 /* ipc_rmid() may have already freed the ID while ipc_lock
524 * was spinning: here verify that the structure is still valid
527 spin_unlock(&out
->lock
);
534 void ipc_lock_by_ptr(struct kern_ipc_perm
*perm
)
537 spin_lock(&perm
->lock
);
540 void ipc_unlock(struct kern_ipc_perm
* perm
)
542 spin_unlock(&perm
->lock
);
546 int ipc_buildid(struct ipc_ids
* ids
, int id
, int seq
)
548 return SEQ_MULTIPLIER
*seq
+ id
;
551 int ipc_checkid(struct ipc_ids
* ids
, struct kern_ipc_perm
* ipcp
, int uid
)
553 if(uid
/SEQ_MULTIPLIER
!= ipcp
->seq
)
558 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
562 * ipc_parse_version - IPC call version
563 * @cmd: pointer to command
565 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
566 * The cmd value is turned from an encoding command and version into
567 * just the command code.
570 int ipc_parse_version (int *cmd
)
580 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
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