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 #if defined(CONFIG_SYSVIPC)
33 * ipc_init - initialise IPC subsystem
35 * The various system5 IPC resources (semaphores, messages and shared
36 * memory are initialised
39 void __init
ipc_init (void)
48 * ipc_init_ids - initialise IPC identifiers
49 * @ids: Identifier set
50 * @size: Number of identifiers
52 * Given a size for the ipc identifier range (limited below IPCMNI)
53 * set up the sequence range to use then allocate and initialise the
57 void __init
ipc_init_ids(struct ipc_ids
* ids
, int size
)
60 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 ipc_id
)*size
);
78 if(ids
->entries
== NULL
) {
79 printk(KERN_ERR
"ipc_init_ids() failed, ipc service disabled.\n");
82 for(i
=0;i
<ids
->size
;i
++)
83 ids
->entries
[i
].p
= NULL
;
87 * ipc_findkey - find a key in an ipc identifier set
88 * @ids: Identifier set
89 * @key: The key to find
91 * Requires ipc_ids.sem locked.
92 * Returns the identifier if found or -1 if not.
95 int ipc_findkey(struct ipc_ids
* ids
, key_t key
)
98 struct kern_ipc_perm
* p
;
99 int max_id
= ids
->max_id
;
102 * read_barrier_depends is not needed here
103 * since ipc_ids.sem is held
105 for (id
= 0; id
<= max_id
; id
++) {
106 p
= ids
->entries
[id
].p
;
116 * Requires ipc_ids.sem locked
118 static int grow_ary(struct ipc_ids
* ids
, int newsize
)
126 if(newsize
<= ids
->size
)
129 new = ipc_rcu_alloc(sizeof(struct ipc_id
)*newsize
);
132 memcpy(new, ids
->entries
, sizeof(struct ipc_id
)*ids
->size
);
133 for(i
=ids
->size
;i
<newsize
;i
++) {
140 * before setting the ids->entries to the new array, there must be a
141 * smp_wmb() to make sure the memcpyed contents of the new array are
142 * visible before the new array becomes visible.
144 smp_wmb(); /* prevent seeing new array uninitialized. */
146 smp_wmb(); /* prevent indexing into old array based on new size. */
149 ipc_rcu_free(old
, sizeof(struct ipc_id
)*i
);
154 * ipc_addid - add an IPC identifier
155 * @ids: IPC identifier set
156 * @new: new IPC permission set
157 * @size: new size limit for the id array
159 * Add an entry 'new' to the IPC arrays. The permissions object is
160 * initialised and the first free entry is set up and the id assigned
161 * is returned. The list is returned in a locked state on success.
162 * On failure the list is not locked and -1 is returned.
164 * Called with ipc_ids.sem held.
167 int ipc_addid(struct ipc_ids
* ids
, struct kern_ipc_perm
* new, int size
)
171 size
= grow_ary(ids
,size
);
174 * read_barrier_depends() is not needed here since
175 * ipc_ids.sem is held
177 for (id
= 0; id
< size
; id
++) {
178 if(ids
->entries
[id
].p
== NULL
)
184 if (id
> ids
->max_id
)
187 new->cuid
= new->uid
= current
->euid
;
188 new->gid
= new->cgid
= current
->egid
;
190 new->seq
= ids
->seq
++;
191 if(ids
->seq
> ids
->seq_max
)
194 new->lock
= SPIN_LOCK_UNLOCKED
;
197 spin_lock(&new->lock
);
198 ids
->entries
[id
].p
= new;
203 * ipc_rmid - remove an IPC identifier
204 * @ids: identifier set
205 * @id: Identifier to remove
207 * The identifier must be valid, and in use. The kernel will panic if
208 * fed an invalid identifier. The entry is removed and internal
209 * variables recomputed. The object associated with the identifier
211 * ipc_ids.sem and the spinlock for this ID is hold before this function
212 * is called, and remain locked on the exit.
215 struct kern_ipc_perm
* ipc_rmid(struct ipc_ids
* ids
, int id
)
217 struct kern_ipc_perm
* p
;
218 int lid
= id
% SEQ_MULTIPLIER
;
223 * do not need a read_barrier_depends() here to force ordering
224 * on Alpha, since the ipc_ids.sem is held.
226 p
= ids
->entries
[lid
].p
;
227 ids
->entries
[lid
].p
= NULL
;
232 if (lid
== ids
->max_id
) {
237 } while (ids
->entries
[lid
].p
== NULL
);
245 * ipc_alloc - allocate ipc space
246 * @size: size desired
248 * Allocate memory from the appropriate pools and return a pointer to it.
249 * NULL is returned if the allocation fails
252 void* ipc_alloc(int size
)
258 out
= kmalloc(size
, GFP_KERNEL
);
263 * ipc_free - free ipc space
264 * @ptr: pointer returned by ipc_alloc
265 * @size: size of block
267 * Free a block created with ipc_alloc. The caller must know the size
268 * used in the allocation call.
271 void ipc_free(void* ptr
, int size
)
279 struct ipc_rcu_kmalloc
282 /* "void *" makes sure alignment of following data is sane. */
286 struct ipc_rcu_vmalloc
289 struct work_struct work
;
290 /* "void *" makes sure alignment of following data is sane. */
294 static inline int rcu_use_vmalloc(int size
)
296 /* Too big for a single page? */
297 if (sizeof(struct ipc_rcu_kmalloc
) + size
> PAGE_SIZE
)
303 * ipc_rcu_alloc - allocate ipc and rcu space
304 * @size: size desired
306 * Allocate memory for the rcu header structure + the object.
307 * Returns the pointer to the object.
308 * NULL is returned if the allocation fails.
311 void* ipc_rcu_alloc(int size
)
315 * We prepend the allocation with the rcu struct, and
316 * workqueue if necessary (for vmalloc).
318 if (rcu_use_vmalloc(size
)) {
319 out
= vmalloc(sizeof(struct ipc_rcu_vmalloc
) + size
);
320 if (out
) out
+= sizeof(struct ipc_rcu_vmalloc
);
322 out
= kmalloc(sizeof(struct ipc_rcu_kmalloc
)+size
, GFP_KERNEL
);
323 if (out
) out
+= sizeof(struct ipc_rcu_kmalloc
);
330 * ipc_schedule_free - free ipc + rcu space
332 * Since RCU callback function is called in bh,
333 * we need to defer the vfree to schedule_work
335 static void ipc_schedule_free(void* arg
)
337 struct ipc_rcu_vmalloc
*free
= arg
;
339 INIT_WORK(&free
->work
, vfree
, free
);
340 schedule_work(&free
->work
);
343 void ipc_rcu_free(void* ptr
, int size
)
345 if (rcu_use_vmalloc(size
)) {
346 struct ipc_rcu_vmalloc
*free
;
347 free
= ptr
- sizeof(*free
);
348 call_rcu(&free
->rcu
, ipc_schedule_free
, free
);
350 struct ipc_rcu_kmalloc
*free
;
351 free
= ptr
- sizeof(*free
);
352 /* kfree takes a "const void *" so gcc warns. So we cast. */
353 call_rcu(&free
->rcu
, (void (*)(void *))kfree
, free
);
359 * ipcperms - check IPC permissions
360 * @ipcp: IPC permission set
361 * @flag: desired permission set.
363 * Check user, group, other permissions for access
364 * to ipc resources. return 0 if allowed
367 int ipcperms (struct kern_ipc_perm
*ipcp
, short flag
)
368 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
369 int requested_mode
, granted_mode
;
371 requested_mode
= (flag
>> 6) | (flag
>> 3) | flag
;
372 granted_mode
= ipcp
->mode
;
373 if (current
->euid
== ipcp
->cuid
|| current
->euid
== ipcp
->uid
)
375 else if (in_group_p(ipcp
->cgid
) || in_group_p(ipcp
->gid
))
377 /* is there some bit set in requested_mode but not in granted_mode? */
378 if ((requested_mode
& ~granted_mode
& 0007) &&
379 !capable(CAP_IPC_OWNER
))
382 return security_ipc_permission(ipcp
, flag
);
386 * Functions to convert between the kern_ipc_perm structure and the
387 * old/new ipc_perm structures
391 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
392 * @in: kernel permissions
393 * @out: new style IPC permissions
395 * Turn the kernel object 'in' into a set of permissions descriptions
396 * for returning to userspace (out).
400 void kernel_to_ipc64_perm (struct kern_ipc_perm
*in
, struct ipc64_perm
*out
)
405 out
->cuid
= in
->cuid
;
406 out
->cgid
= in
->cgid
;
407 out
->mode
= in
->mode
;
412 * ipc64_perm_to_ipc_perm - convert old ipc permissions to new
413 * @in: new style IPC permissions
414 * @out: old style IPC permissions
416 * Turn the new style permissions object in into a compatibility
417 * object and store it into the 'out' pointer.
420 void ipc64_perm_to_ipc_perm (struct ipc64_perm
*in
, struct ipc_perm
*out
)
423 out
->uid
= NEW_TO_OLD_UID(in
->uid
);
424 out
->gid
= NEW_TO_OLD_GID(in
->gid
);
425 out
->cuid
= NEW_TO_OLD_UID(in
->cuid
);
426 out
->cgid
= NEW_TO_OLD_GID(in
->cgid
);
427 out
->mode
= in
->mode
;
432 * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
433 * is called with shm_ids.sem locked. Since grow_ary() is also called with
434 * shm_ids.sem down(for Shared Memory), there is no need to add read
435 * barriers here to gurantee the writes in grow_ary() are seen in order
438 * However ipc_get() itself does not necessary require ipc_ids.sem down. So
439 * if in the future ipc_get() is used by other places without ipc_ids.sem
440 * down, then ipc_get() needs read memery barriers as ipc_lock() does.
442 struct kern_ipc_perm
* ipc_get(struct ipc_ids
* ids
, int id
)
444 struct kern_ipc_perm
* out
;
445 int lid
= id
% SEQ_MULTIPLIER
;
448 out
= ids
->entries
[lid
].p
;
452 struct kern_ipc_perm
* ipc_lock(struct ipc_ids
* ids
, int id
)
454 struct kern_ipc_perm
* out
;
455 int lid
= id
% SEQ_MULTIPLIER
;
456 struct ipc_id
* entries
;
459 if(lid
>= ids
->size
) {
465 * Note: The following two read barriers are corresponding
466 * to the two write barriers in grow_ary(). They guarantee
467 * the writes are seen in the same order on the read side.
468 * smp_rmb() has effect on all CPUs. read_barrier_depends()
469 * is used if there are data dependency between two reads, and
470 * has effect only on Alpha.
472 smp_rmb(); /* prevent indexing old array with new size */
473 entries
= ids
->entries
;
474 read_barrier_depends(); /*prevent seeing new array unitialized */
475 out
= entries
[lid
].p
;
480 spin_lock(&out
->lock
);
482 /* ipc_rmid() may have already freed the ID while ipc_lock
483 * was spinning: here verify that the structure is still valid
486 spin_unlock(&out
->lock
);
493 void ipc_unlock(struct kern_ipc_perm
* perm
)
495 spin_unlock(&perm
->lock
);
499 int ipc_buildid(struct ipc_ids
* ids
, int id
, int seq
)
501 return SEQ_MULTIPLIER
*seq
+ id
;
504 int ipc_checkid(struct ipc_ids
* ids
, struct kern_ipc_perm
* ipcp
, int uid
)
506 if(uid
/SEQ_MULTIPLIER
!= ipcp
->seq
)
511 #if !defined(__ia64__) && !defined(__x86_64__)
514 * ipc_parse_version - IPC call version
515 * @cmd: pointer to command
517 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
518 * The cmd value is turned from an encoding command and version into
519 * just the command code.
522 int ipc_parse_version (int *cmd
)
532 #endif /* __ia64__ */
536 * Dummy functions when SYSV IPC isn't configured
539 int copy_semundo(unsigned long clone_flags
, struct task_struct
*tsk
)
544 void exit_sem(struct task_struct
*tsk
)
549 asmlinkage
long sys_semget (key_t key
, int nsems
, int semflg
)
554 asmlinkage
long sys_semop (int semid
, struct sembuf
*sops
, unsigned nsops
)
559 asmlinkage
long sys_semtimedop(int semid
, struct sembuf
*sops
, unsigned nsops
,
560 const struct timespec
*timeout
)
566 asmlinkage
long sys_semctl (int semid
, int semnum
, int cmd
, union semun arg
)
571 asmlinkage
long sys_msgget (key_t key
, int msgflg
)
576 asmlinkage
long sys_msgsnd (int msqid
, struct msgbuf
*msgp
, size_t msgsz
, int msgflg
)
581 asmlinkage
long sys_msgrcv (int msqid
, struct msgbuf
*msgp
, size_t msgsz
, long msgtyp
,
587 asmlinkage
long sys_msgctl (int msqid
, int cmd
, struct msqid_ds
*buf
)
592 asmlinkage
long sys_shmget (key_t key
, size_t size
, int shmflag
)
597 asmlinkage
long sys_shmat (int shmid
, char *shmaddr
, int shmflg
, ulong
*addr
)
602 asmlinkage
long sys_shmdt (char *shmaddr
)
607 asmlinkage
long sys_shmctl (int shmid
, int cmd
, struct shmid_ds
*buf
)
612 #endif /* CONFIG_SYSVIPC */