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>
27 #include <linux/vs_base.h>
29 #include <asm/unistd.h>
31 #include <asm/unistd.h>
36 * ipc_init - initialise IPC subsystem
38 * The various system5 IPC resources (semaphores, messages and shared
39 * memory are initialised
42 static int __init ipc_init(void)
52 * ipc_init_ids - initialise IPC identifiers
53 * @ids: Identifier set
54 * @size: Number of identifiers
56 * Given a size for the ipc identifier range (limited below IPCMNI)
57 * set up the sequence range to use then allocate and initialise the
61 void __init ipc_init_ids(struct ipc_ids* ids, int size)
64 sema_init(&ids->sem,1);
73 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
74 if(seq_limit > USHRT_MAX)
75 ids->seq_max = USHRT_MAX;
77 ids->seq_max = seq_limit;
80 ids->entries = ipc_rcu_alloc(sizeof(struct ipc_id)*size);
82 if(ids->entries == NULL) {
83 printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
86 for(i=0;i<ids->size;i++)
87 ids->entries[i].p = NULL;
91 * ipc_findkey - find a key in an ipc identifier set
92 * @ids: Identifier set
93 * @key: The key to find
95 * Requires ipc_ids.sem locked.
96 * Returns the identifier if found or -1 if not.
99 int ipc_findkey(struct ipc_ids* ids, key_t key)
102 struct kern_ipc_perm* p;
103 int max_id = ids->max_id;
106 * read_barrier_depends is not needed here
107 * since ipc_ids.sem is held
109 for (id = 0; id <= max_id; id++) {
110 p = ids->entries[id].p;
113 if (!vx_check(p->xid, VX_IDENT))
122 * Requires ipc_ids.sem locked
124 static int grow_ary(struct ipc_ids* ids, int newsize)
132 if(newsize <= ids->size)
135 new = ipc_rcu_alloc(sizeof(struct ipc_id)*newsize);
138 memcpy(new, ids->entries, sizeof(struct ipc_id)*ids->size);
139 for(i=ids->size;i<newsize;i++) {
146 * before setting the ids->entries to the new array, there must be a
147 * smp_wmb() to make sure the memcpyed contents of the new array are
148 * visible before the new array becomes visible.
150 smp_wmb(); /* prevent seeing new array uninitialized. */
152 smp_wmb(); /* prevent indexing into old array based on new size. */
155 ipc_rcu_free(old, sizeof(struct ipc_id)*i);
160 * ipc_addid - add an IPC identifier
161 * @ids: IPC identifier set
162 * @new: new IPC permission set
163 * @size: new size limit for the id array
165 * Add an entry 'new' to the IPC arrays. The permissions object is
166 * initialised and the first free entry is set up and the id assigned
167 * is returned. The list is returned in a locked state on success.
168 * On failure the list is not locked and -1 is returned.
170 * Called with ipc_ids.sem held.
173 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
177 size = grow_ary(ids,size);
180 * read_barrier_depends() is not needed here since
181 * ipc_ids.sem is held
183 for (id = 0; id < size; id++) {
184 if(ids->entries[id].p == NULL)
190 if (id > ids->max_id)
193 new->cuid = new->uid = current->euid;
194 new->gid = new->cgid = current->egid;
196 new->seq = ids->seq++;
197 if(ids->seq > ids->seq_max)
200 new->lock = SPIN_LOCK_UNLOCKED;
203 spin_lock(&new->lock);
204 ids->entries[id].p = new;
209 * ipc_rmid - remove an IPC identifier
210 * @ids: identifier set
211 * @id: Identifier to remove
213 * The identifier must be valid, and in use. The kernel will panic if
214 * fed an invalid identifier. The entry is removed and internal
215 * variables recomputed. The object associated with the identifier
217 * ipc_ids.sem and the spinlock for this ID is hold before this function
218 * is called, and remain locked on the exit.
221 struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
223 struct kern_ipc_perm* p;
224 int lid = id % SEQ_MULTIPLIER;
229 * do not need a read_barrier_depends() here to force ordering
230 * on Alpha, since the ipc_ids.sem is held.
232 p = ids->entries[lid].p;
233 ids->entries[lid].p = NULL;
238 if (lid == ids->max_id) {
243 } while (ids->entries[lid].p == NULL);
251 * ipc_alloc - allocate ipc space
252 * @size: size desired
254 * Allocate memory from the appropriate pools and return a pointer to it.
255 * NULL is returned if the allocation fails
258 void* ipc_alloc(int size)
264 out = kmalloc(size, GFP_KERNEL);
269 * ipc_free - free ipc space
270 * @ptr: pointer returned by ipc_alloc
271 * @size: size of block
273 * Free a block created with ipc_alloc. The caller must know the size
274 * used in the allocation call.
277 void ipc_free(void* ptr, int size)
285 struct ipc_rcu_kmalloc
288 /* "void *" makes sure alignment of following data is sane. */
292 struct ipc_rcu_vmalloc
295 struct work_struct work;
296 /* "void *" makes sure alignment of following data is sane. */
300 static inline int rcu_use_vmalloc(int size)
302 /* Too big for a single page? */
303 if (sizeof(struct ipc_rcu_kmalloc) + size > PAGE_SIZE)
309 * ipc_rcu_alloc - allocate ipc and rcu space
310 * @size: size desired
312 * Allocate memory for the rcu header structure + the object.
313 * Returns the pointer to the object.
314 * NULL is returned if the allocation fails.
317 void* ipc_rcu_alloc(int size)
321 * We prepend the allocation with the rcu struct, and
322 * workqueue if necessary (for vmalloc).
324 if (rcu_use_vmalloc(size)) {
325 out = vmalloc(sizeof(struct ipc_rcu_vmalloc) + size);
326 if (out) out += sizeof(struct ipc_rcu_vmalloc);
328 out = kmalloc(sizeof(struct ipc_rcu_kmalloc)+size, GFP_KERNEL);
329 if (out) out += sizeof(struct ipc_rcu_kmalloc);
336 * ipc_schedule_free - free ipc + rcu space
338 * Since RCU callback function is called in bh,
339 * we need to defer the vfree to schedule_work
341 static void ipc_schedule_free(struct rcu_head *head)
343 struct ipc_rcu_vmalloc *free =
344 container_of(head, struct ipc_rcu_vmalloc, rcu);
346 INIT_WORK(&free->work, vfree, free);
347 schedule_work(&free->work);
351 * ipc_immediate_free - free ipc + rcu space
353 * Free from the RCU callback context
356 static void ipc_immediate_free(struct rcu_head *head)
358 struct ipc_rcu_kmalloc *free =
359 container_of(head, struct ipc_rcu_kmalloc, rcu);
365 void ipc_rcu_free(void* ptr, int size)
367 if (rcu_use_vmalloc(size)) {
368 struct ipc_rcu_vmalloc *free;
369 free = ptr - sizeof(*free);
370 call_rcu(&free->rcu, ipc_schedule_free);
372 struct ipc_rcu_kmalloc *free;
373 free = ptr - sizeof(*free);
374 call_rcu(&free->rcu, ipc_immediate_free);
380 * ipcperms - check IPC permissions
381 * @ipcp: IPC permission set
382 * @flag: desired permission set.
384 * Check user, group, other permissions for access
385 * to ipc resources. return 0 if allowed
388 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
389 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
390 int requested_mode, granted_mode;
392 if (!vx_check(ipcp->xid, VX_ADMIN|VX_IDENT)) /* maybe just VX_IDENT? */
394 requested_mode = (flag >> 6) | (flag >> 3) | flag;
395 granted_mode = ipcp->mode;
396 if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
398 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
400 /* is there some bit set in requested_mode but not in granted_mode? */
401 if ((requested_mode & ~granted_mode & 0007) &&
402 !capable(CAP_IPC_OWNER)) {
403 if (!can_do_mlock()) {
408 return security_ipc_permission(ipcp, flag);
412 * Functions to convert between the kern_ipc_perm structure and the
413 * old/new ipc_perm structures
417 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
418 * @in: kernel permissions
419 * @out: new style IPC permissions
421 * Turn the kernel object 'in' into a set of permissions descriptions
422 * for returning to userspace (out).
426 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
431 out->cuid = in->cuid;
432 out->cgid = in->cgid;
433 out->mode = in->mode;
438 * ipc64_perm_to_ipc_perm - convert old ipc permissions to new
439 * @in: new style IPC permissions
440 * @out: old style IPC permissions
442 * Turn the new style permissions object in into a compatibility
443 * object and store it into the 'out' pointer.
446 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
449 SET_UID(out->uid, in->uid);
450 SET_GID(out->gid, in->gid);
451 SET_UID(out->cuid, in->cuid);
452 SET_GID(out->cgid, in->cgid);
453 out->mode = in->mode;
458 * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
459 * is called with shm_ids.sem locked. Since grow_ary() is also called with
460 * shm_ids.sem down(for Shared Memory), there is no need to add read
461 * barriers here to gurantee the writes in grow_ary() are seen in order
464 * However ipc_get() itself does not necessary require ipc_ids.sem down. So
465 * if in the future ipc_get() is used by other places without ipc_ids.sem
466 * down, then ipc_get() needs read memery barriers as ipc_lock() does.
468 struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id)
470 struct kern_ipc_perm* out;
471 int lid = id % SEQ_MULTIPLIER;
474 out = ids->entries[lid].p;
478 struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
480 struct kern_ipc_perm* out;
481 int lid = id % SEQ_MULTIPLIER;
482 struct ipc_id* entries;
485 if(lid >= ids->size) {
491 * Note: The following two read barriers are corresponding
492 * to the two write barriers in grow_ary(). They guarantee
493 * the writes are seen in the same order on the read side.
494 * smp_rmb() has effect on all CPUs. read_barrier_depends()
495 * is used if there are data dependency between two reads, and
496 * has effect only on Alpha.
498 smp_rmb(); /* prevent indexing old array with new size */
499 entries = ids->entries;
500 read_barrier_depends(); /*prevent seeing new array unitialized */
501 out = entries[lid].p;
506 spin_lock(&out->lock);
508 /* ipc_rmid() may have already freed the ID while ipc_lock
509 * was spinning: here verify that the structure is still valid
512 spin_unlock(&out->lock);
519 void ipc_unlock(struct kern_ipc_perm* perm)
521 spin_unlock(&perm->lock);
525 int ipc_buildid(struct ipc_ids* ids, int id, int seq)
527 return SEQ_MULTIPLIER*seq + id;
530 int ipc_checkid(struct ipc_ids* ids, struct kern_ipc_perm* ipcp, int uid)
532 if(uid/SEQ_MULTIPLIER != ipcp->seq)
537 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
541 * ipc_parse_version - IPC call version
542 * @cmd: pointer to command
544 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
545 * The cmd value is turned from an encoding command and version into
546 * just the command code.
549 int ipc_parse_version (int *cmd)
559 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */