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1 /*
2 * linux/ipc/util.c
3 * Copyright (C) 1992 Krishna Balasubramanian
4 *
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
16 * OpenVZ, SWsoft Inc.
17 * Pavel Emelianov <xemul@openvz.org>
18 */
19
20 #include <linux/mm.h>
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/capability.h>
27 #include <linux/highuid.h>
28 #include <linux/security.h>
29 #include <linux/rcupdate.h>
30 #include <linux/workqueue.h>
31 #include <linux/seq_file.h>
32 #include <linux/proc_fs.h>
33 #include <linux/audit.h>
34 #include <linux/nsproxy.h>
35 #include <linux/rwsem.h>
36 #include <linux/memory.h>
37 #include <linux/ipc_namespace.h>
38
39 #include <asm/unistd.h>
40
41 #include "util.h"
42
43 struct ipc_proc_iface {
44 const char *path;
45 const char *header;
46 int ids;
47 int (*show)(struct seq_file *, void *);
48 };
49
50 #ifdef CONFIG_MEMORY_HOTPLUG
51
52 static void ipc_memory_notifier(struct work_struct *work)
53 {
54 ipcns_notify(IPCNS_MEMCHANGED);
55 }
56
57 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
58
59
60 static int ipc_memory_callback(struct notifier_block *self,
61 unsigned long action, void *arg)
62 {
63 switch (action) {
64 case MEM_ONLINE: /* memory successfully brought online */
65 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
66 /*
67 * This is done by invoking the ipcns notifier chain with the
68 * IPC_MEMCHANGED event.
69 * In order not to keep the lock on the hotplug memory chain
70 * for too long, queue a work item that will, when waken up,
71 * activate the ipcns notification chain.
72 * No need to keep several ipc work items on the queue.
73 */
74 if (!work_pending(&ipc_memory_wq))
75 schedule_work(&ipc_memory_wq);
76 break;
77 case MEM_GOING_ONLINE:
78 case MEM_GOING_OFFLINE:
79 case MEM_CANCEL_ONLINE:
80 case MEM_CANCEL_OFFLINE:
81 default:
82 break;
83 }
84
85 return NOTIFY_OK;
86 }
87
88 #endif /* CONFIG_MEMORY_HOTPLUG */
89
90 /**
91 * ipc_init - initialise IPC subsystem
92 *
93 * The various system5 IPC resources (semaphores, messages and shared
94 * memory) are initialised
95 * A callback routine is registered into the memory hotplug notifier
96 * chain: since msgmni scales to lowmem this callback routine will be
97 * called upon successful memory add / remove to recompute msmgni.
98 */
99
100 static int __init ipc_init(void)
101 {
102 sem_init();
103 msg_init();
104 shm_init();
105 hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
106 register_ipcns_notifier(&init_ipc_ns);
107 return 0;
108 }
109 __initcall(ipc_init);
110
111 /**
112 * ipc_init_ids - initialise IPC identifiers
113 * @ids: Identifier set
114 *
115 * Set up the sequence range to use for the ipc identifier range (limited
116 * below IPCMNI) then initialise the ids idr.
117 */
118
119 void ipc_init_ids(struct ipc_ids *ids)
120 {
121 init_rwsem(&ids->rw_mutex);
122
123 ids->in_use = 0;
124 ids->seq = 0;
125 {
126 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
127 if (seq_limit > USHRT_MAX)
128 ids->seq_max = USHRT_MAX;
129 else
130 ids->seq_max = seq_limit;
131 }
132
133 idr_init(&ids->ipcs_idr);
134 }
135
136 #ifdef CONFIG_PROC_FS
137 static const struct file_operations sysvipc_proc_fops;
138 /**
139 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
140 * @path: Path in procfs
141 * @header: Banner to be printed at the beginning of the file.
142 * @ids: ipc id table to iterate.
143 * @show: show routine.
144 */
145 void __init ipc_init_proc_interface(const char *path, const char *header,
146 int ids, int (*show)(struct seq_file *, void *))
147 {
148 struct proc_dir_entry *pde;
149 struct ipc_proc_iface *iface;
150
151 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
152 if (!iface)
153 return;
154 iface->path = path;
155 iface->header = header;
156 iface->ids = ids;
157 iface->show = show;
158
159 pde = proc_create_data(path,
160 S_IRUGO, /* world readable */
161 NULL, /* parent dir */
162 &sysvipc_proc_fops,
163 iface);
164 if (!pde) {
165 kfree(iface);
166 }
167 }
168 #endif
169
170 /**
171 * ipc_findkey - find a key in an ipc identifier set
172 * @ids: Identifier set
173 * @key: The key to find
174 *
175 * Requires ipc_ids.rw_mutex locked.
176 * Returns the LOCKED pointer to the ipc structure if found or NULL
177 * if not.
178 * If key is found ipc points to the owning ipc structure
179 */
180
181 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
182 {
183 struct kern_ipc_perm *ipc;
184 int next_id;
185 int total;
186
187 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
188 ipc = idr_find(&ids->ipcs_idr, next_id);
189
190 if (ipc == NULL)
191 continue;
192
193 if (ipc->key != key) {
194 total++;
195 continue;
196 }
197
198 ipc_lock_by_ptr(ipc);
199 return ipc;
200 }
201
202 return NULL;
203 }
204
205 /**
206 * ipc_get_maxid - get the last assigned id
207 * @ids: IPC identifier set
208 *
209 * Called with ipc_ids.rw_mutex held.
210 */
211
212 int ipc_get_maxid(struct ipc_ids *ids)
213 {
214 struct kern_ipc_perm *ipc;
215 int max_id = -1;
216 int total, id;
217
218 if (ids->in_use == 0)
219 return -1;
220
221 if (ids->in_use == IPCMNI)
222 return IPCMNI - 1;
223
224 /* Look for the last assigned id */
225 total = 0;
226 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
227 ipc = idr_find(&ids->ipcs_idr, id);
228 if (ipc != NULL) {
229 max_id = id;
230 total++;
231 }
232 }
233 return max_id;
234 }
235
236 /**
237 * ipc_addid - add an IPC identifier
238 * @ids: IPC identifier set
239 * @new: new IPC permission set
240 * @size: limit for the number of used ids
241 *
242 * Add an entry 'new' to the IPC ids idr. The permissions object is
243 * initialised and the first free entry is set up and the id assigned
244 * is returned. The 'new' entry is returned in a locked state on success.
245 * On failure the entry is not locked and a negative err-code is returned.
246 *
247 * Called with ipc_ids.rw_mutex held as a writer.
248 */
249
250 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
251 {
252 uid_t euid;
253 gid_t egid;
254 int id, err;
255
256 if (size > IPCMNI)
257 size = IPCMNI;
258
259 if (ids->in_use >= size)
260 return -ENOSPC;
261
262 spin_lock_init(&new->lock);
263 new->deleted = 0;
264 rcu_read_lock();
265 spin_lock(&new->lock);
266
267 err = idr_get_new(&ids->ipcs_idr, new, &id);
268 if (err) {
269 spin_unlock(&new->lock);
270 rcu_read_unlock();
271 return err;
272 }
273
274 ids->in_use++;
275
276 current_euid_egid(&euid, &egid);
277 new->cuid = new->uid = euid;
278 new->gid = new->cgid = egid;
279
280 new->seq = ids->seq++;
281 if(ids->seq > ids->seq_max)
282 ids->seq = 0;
283
284 new->id = ipc_buildid(id, new->seq);
285 return id;
286 }
287
288 /**
289 * ipcget_new - create a new ipc object
290 * @ns: namespace
291 * @ids: IPC identifer set
292 * @ops: the actual creation routine to call
293 * @params: its parameters
294 *
295 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
296 * when the key is IPC_PRIVATE.
297 */
298 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
299 struct ipc_ops *ops, struct ipc_params *params)
300 {
301 int err;
302 retry:
303 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
304
305 if (!err)
306 return -ENOMEM;
307
308 down_write(&ids->rw_mutex);
309 err = ops->getnew(ns, params);
310 up_write(&ids->rw_mutex);
311
312 if (err == -EAGAIN)
313 goto retry;
314
315 return err;
316 }
317
318 /**
319 * ipc_check_perms - check security and permissions for an IPC
320 * @ipcp: ipc permission set
321 * @ops: the actual security routine to call
322 * @params: its parameters
323 *
324 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
325 * when the key is not IPC_PRIVATE and that key already exists in the
326 * ids IDR.
327 *
328 * On success, the IPC id is returned.
329 *
330 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
331 */
332 static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
333 struct ipc_params *params)
334 {
335 int err;
336
337 if (ipcperms(ipcp, params->flg))
338 err = -EACCES;
339 else {
340 err = ops->associate(ipcp, params->flg);
341 if (!err)
342 err = ipcp->id;
343 }
344
345 return err;
346 }
347
348 /**
349 * ipcget_public - get an ipc object or create a new one
350 * @ns: namespace
351 * @ids: IPC identifer set
352 * @ops: the actual creation routine to call
353 * @params: its parameters
354 *
355 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
356 * when the key is not IPC_PRIVATE.
357 * It adds a new entry if the key is not found and does some permission
358 * / security checkings if the key is found.
359 *
360 * On success, the ipc id is returned.
361 */
362 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
363 struct ipc_ops *ops, struct ipc_params *params)
364 {
365 struct kern_ipc_perm *ipcp;
366 int flg = params->flg;
367 int err;
368 retry:
369 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
370
371 /*
372 * Take the lock as a writer since we are potentially going to add
373 * a new entry + read locks are not "upgradable"
374 */
375 down_write(&ids->rw_mutex);
376 ipcp = ipc_findkey(ids, params->key);
377 if (ipcp == NULL) {
378 /* key not used */
379 if (!(flg & IPC_CREAT))
380 err = -ENOENT;
381 else if (!err)
382 err = -ENOMEM;
383 else
384 err = ops->getnew(ns, params);
385 } else {
386 /* ipc object has been locked by ipc_findkey() */
387
388 if (flg & IPC_CREAT && flg & IPC_EXCL)
389 err = -EEXIST;
390 else {
391 err = 0;
392 if (ops->more_checks)
393 err = ops->more_checks(ipcp, params);
394 if (!err)
395 /*
396 * ipc_check_perms returns the IPC id on
397 * success
398 */
399 err = ipc_check_perms(ipcp, ops, params);
400 }
401 ipc_unlock(ipcp);
402 }
403 up_write(&ids->rw_mutex);
404
405 if (err == -EAGAIN)
406 goto retry;
407
408 return err;
409 }
410
411
412 /**
413 * ipc_rmid - remove an IPC identifier
414 * @ids: IPC identifier set
415 * @ipcp: ipc perm structure containing the identifier to remove
416 *
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.
419 */
420
421 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
422 {
423 int lid = ipcid_to_idx(ipcp->id);
424
425 idr_remove(&ids->ipcs_idr, lid);
426
427 ids->in_use--;
428
429 ipcp->deleted = 1;
430
431 return;
432 }
433
434 /**
435 * ipc_alloc - allocate ipc space
436 * @size: size desired
437 *
438 * Allocate memory from the appropriate pools and return a pointer to it.
439 * NULL is returned if the allocation fails
440 */
441
442 void* ipc_alloc(int size)
443 {
444 void* out;
445 if(size > PAGE_SIZE)
446 out = vmalloc(size);
447 else
448 out = kmalloc(size, GFP_KERNEL);
449 return out;
450 }
451
452 /**
453 * ipc_free - free ipc space
454 * @ptr: pointer returned by ipc_alloc
455 * @size: size of block
456 *
457 * Free a block created with ipc_alloc(). The caller must know the size
458 * used in the allocation call.
459 */
460
461 void ipc_free(void* ptr, int size)
462 {
463 if(size > PAGE_SIZE)
464 vfree(ptr);
465 else
466 kfree(ptr);
467 }
468
469 /*
470 * rcu allocations:
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:
478 */
479 struct ipc_rcu_hdr
480 {
481 int refcount;
482 int is_vmalloc;
483 void *data[0];
484 };
485
486
487 struct ipc_rcu_grace
488 {
489 struct rcu_head rcu;
490 /* "void *" makes sure alignment of following data is sane. */
491 void *data[0];
492 };
493
494 struct ipc_rcu_sched
495 {
496 struct work_struct work;
497 /* "void *" makes sure alignment of following data is sane. */
498 void *data[0];
499 };
500
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)
505
506 static inline int rcu_use_vmalloc(int size)
507 {
508 /* Too big for a single page? */
509 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
510 return 1;
511 return 0;
512 }
513
514 /**
515 * ipc_rcu_alloc - allocate ipc and rcu space
516 * @size: size desired
517 *
518 * Allocate memory for the rcu header structure + the object.
519 * Returns the pointer to the object.
520 * NULL is returned if the allocation fails.
521 */
522
523 void* ipc_rcu_alloc(int size)
524 {
525 void* out;
526 /*
527 * We prepend the allocation with the rcu struct, and
528 * workqueue if necessary (for vmalloc).
529 */
530 if (rcu_use_vmalloc(size)) {
531 out = vmalloc(HDRLEN_VMALLOC + size);
532 if (out) {
533 out += HDRLEN_VMALLOC;
534 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
535 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
536 }
537 } else {
538 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
539 if (out) {
540 out += HDRLEN_KMALLOC;
541 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
542 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
543 }
544 }
545
546 return out;
547 }
548
549 void ipc_rcu_getref(void *ptr)
550 {
551 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
552 }
553
554 static void ipc_do_vfree(struct work_struct *work)
555 {
556 vfree(container_of(work, struct ipc_rcu_sched, work));
557 }
558
559 /**
560 * ipc_schedule_free - free ipc + rcu space
561 * @head: RCU callback structure for queued work
562 *
563 * Since RCU callback function is called in bh,
564 * we need to defer the vfree to schedule_work().
565 */
566 static void ipc_schedule_free(struct rcu_head *head)
567 {
568 struct ipc_rcu_grace *grace;
569 struct ipc_rcu_sched *sched;
570
571 grace = container_of(head, struct ipc_rcu_grace, rcu);
572 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
573 data[0]);
574
575 INIT_WORK(&sched->work, ipc_do_vfree);
576 schedule_work(&sched->work);
577 }
578
579 /**
580 * ipc_immediate_free - free ipc + rcu space
581 * @head: RCU callback structure that contains pointer to be freed
582 *
583 * Free from the RCU callback context.
584 */
585 static void ipc_immediate_free(struct rcu_head *head)
586 {
587 struct ipc_rcu_grace *free =
588 container_of(head, struct ipc_rcu_grace, rcu);
589 kfree(free);
590 }
591
592 void ipc_rcu_putref(void *ptr)
593 {
594 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
595 return;
596
597 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
598 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
599 ipc_schedule_free);
600 } else {
601 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
602 ipc_immediate_free);
603 }
604 }
605
606 /**
607 * ipcperms - check IPC permissions
608 * @ipcp: IPC permission set
609 * @flag: desired permission set.
610 *
611 * Check user, group, other permissions for access
612 * to ipc resources. return 0 if allowed
613 */
614
615 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
616 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
617 uid_t euid = current_euid();
618 int requested_mode, granted_mode;
619
620 audit_ipc_obj(ipcp);
621 requested_mode = (flag >> 6) | (flag >> 3) | flag;
622 granted_mode = ipcp->mode;
623 if (euid == ipcp->cuid ||
624 euid == ipcp->uid)
625 granted_mode >>= 6;
626 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
627 granted_mode >>= 3;
628 /* is there some bit set in requested_mode but not in granted_mode? */
629 if ((requested_mode & ~granted_mode & 0007) &&
630 !capable(CAP_IPC_OWNER))
631 return -1;
632
633 return security_ipc_permission(ipcp, flag);
634 }
635
636 /*
637 * Functions to convert between the kern_ipc_perm structure and the
638 * old/new ipc_perm structures
639 */
640
641 /**
642 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
643 * @in: kernel permissions
644 * @out: new style IPC permissions
645 *
646 * Turn the kernel object @in into a set of permissions descriptions
647 * for returning to userspace (@out).
648 */
649
650
651 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
652 {
653 out->key = in->key;
654 out->uid = in->uid;
655 out->gid = in->gid;
656 out->cuid = in->cuid;
657 out->cgid = in->cgid;
658 out->mode = in->mode;
659 out->seq = in->seq;
660 }
661
662 /**
663 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
664 * @in: new style IPC permissions
665 * @out: old style IPC permissions
666 *
667 * Turn the new style permissions object @in into a compatibility
668 * object and store it into the @out pointer.
669 */
670
671 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
672 {
673 out->key = in->key;
674 SET_UID(out->uid, in->uid);
675 SET_GID(out->gid, in->gid);
676 SET_UID(out->cuid, in->cuid);
677 SET_GID(out->cgid, in->cgid);
678 out->mode = in->mode;
679 out->seq = in->seq;
680 }
681
682 /**
683 * ipc_lock - Lock an ipc structure without rw_mutex held
684 * @ids: IPC identifier set
685 * @id: ipc id to look for
686 *
687 * Look for an id in the ipc ids idr and lock the associated ipc object.
688 *
689 * The ipc object is locked on exit.
690 */
691
692 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
693 {
694 struct kern_ipc_perm *out;
695 int lid = ipcid_to_idx(id);
696
697 rcu_read_lock();
698 out = idr_find(&ids->ipcs_idr, lid);
699 if (out == NULL) {
700 rcu_read_unlock();
701 return ERR_PTR(-EINVAL);
702 }
703
704 spin_lock(&out->lock);
705
706 /* ipc_rmid() may have already freed the ID while ipc_lock
707 * was spinning: here verify that the structure is still valid
708 */
709 if (out->deleted) {
710 spin_unlock(&out->lock);
711 rcu_read_unlock();
712 return ERR_PTR(-EINVAL);
713 }
714
715 return out;
716 }
717
718 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
719 {
720 struct kern_ipc_perm *out;
721
722 out = ipc_lock(ids, id);
723 if (IS_ERR(out))
724 return out;
725
726 if (ipc_checkid(out, id)) {
727 ipc_unlock(out);
728 return ERR_PTR(-EIDRM);
729 }
730
731 return out;
732 }
733
734 /**
735 * ipcget - Common sys_*get() code
736 * @ns : namsepace
737 * @ids : IPC identifier set
738 * @ops : operations to be called on ipc object creation, permission checks
739 * and further checks
740 * @params : the parameters needed by the previous operations.
741 *
742 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
743 */
744 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
745 struct ipc_ops *ops, struct ipc_params *params)
746 {
747 if (params->key == IPC_PRIVATE)
748 return ipcget_new(ns, ids, ops, params);
749 else
750 return ipcget_public(ns, ids, ops, params);
751 }
752
753 /**
754 * ipc_update_perm - update the permissions of an IPC.
755 * @in: the permission given as input.
756 * @out: the permission of the ipc to set.
757 */
758 void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
759 {
760 out->uid = in->uid;
761 out->gid = in->gid;
762 out->mode = (out->mode & ~S_IRWXUGO)
763 | (in->mode & S_IRWXUGO);
764 }
765
766 /**
767 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
768 * @ids: the table of ids where to look for the ipc
769 * @id: the id of the ipc to retrieve
770 * @cmd: the cmd to check
771 * @perm: the permission to set
772 * @extra_perm: one extra permission parameter used by msq
773 *
774 * This function does some common audit and permissions check for some IPC_XXX
775 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
776 * It must be called without any lock held and
777 * - retrieves the ipc with the given id in the given table.
778 * - performs some audit and permission check, depending on the given cmd
779 * - returns the ipc with both ipc and rw_mutex locks held in case of success
780 * or an err-code without any lock held otherwise.
781 */
782 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
783 struct ipc64_perm *perm, int extra_perm)
784 {
785 struct kern_ipc_perm *ipcp;
786 uid_t euid;
787 int err;
788
789 down_write(&ids->rw_mutex);
790 ipcp = ipc_lock_check(ids, id);
791 if (IS_ERR(ipcp)) {
792 err = PTR_ERR(ipcp);
793 goto out_up;
794 }
795
796 audit_ipc_obj(ipcp);
797 if (cmd == IPC_SET)
798 audit_ipc_set_perm(extra_perm, perm->uid,
799 perm->gid, perm->mode);
800
801 euid = current_euid();
802 if (euid == ipcp->cuid ||
803 euid == ipcp->uid || capable(CAP_SYS_ADMIN))
804 return ipcp;
805
806 err = -EPERM;
807 ipc_unlock(ipcp);
808 out_up:
809 up_write(&ids->rw_mutex);
810 return ERR_PTR(err);
811 }
812
813 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
814
815
816 /**
817 * ipc_parse_version - IPC call version
818 * @cmd: pointer to command
819 *
820 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
821 * The @cmd value is turned from an encoding command and version into
822 * just the command code.
823 */
824
825 int ipc_parse_version (int *cmd)
826 {
827 if (*cmd & IPC_64) {
828 *cmd ^= IPC_64;
829 return IPC_64;
830 } else {
831 return IPC_OLD;
832 }
833 }
834
835 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
836
837 #ifdef CONFIG_PROC_FS
838 struct ipc_proc_iter {
839 struct ipc_namespace *ns;
840 struct ipc_proc_iface *iface;
841 };
842
843 /*
844 * This routine locks the ipc structure found at least at position pos.
845 */
846 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
847 loff_t *new_pos)
848 {
849 struct kern_ipc_perm *ipc;
850 int total, id;
851
852 total = 0;
853 for (id = 0; id < pos && total < ids->in_use; id++) {
854 ipc = idr_find(&ids->ipcs_idr, id);
855 if (ipc != NULL)
856 total++;
857 }
858
859 if (total >= ids->in_use)
860 return NULL;
861
862 for ( ; pos < IPCMNI; pos++) {
863 ipc = idr_find(&ids->ipcs_idr, pos);
864 if (ipc != NULL) {
865 *new_pos = pos + 1;
866 ipc_lock_by_ptr(ipc);
867 return ipc;
868 }
869 }
870
871 /* Out of range - return NULL to terminate iteration */
872 return NULL;
873 }
874
875 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
876 {
877 struct ipc_proc_iter *iter = s->private;
878 struct ipc_proc_iface *iface = iter->iface;
879 struct kern_ipc_perm *ipc = it;
880
881 /* If we had an ipc id locked before, unlock it */
882 if (ipc && ipc != SEQ_START_TOKEN)
883 ipc_unlock(ipc);
884
885 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
886 }
887
888 /*
889 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
890 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
891 */
892 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
893 {
894 struct ipc_proc_iter *iter = s->private;
895 struct ipc_proc_iface *iface = iter->iface;
896 struct ipc_ids *ids;
897
898 ids = &iter->ns->ids[iface->ids];
899
900 /*
901 * Take the lock - this will be released by the corresponding
902 * call to stop().
903 */
904 down_read(&ids->rw_mutex);
905
906 /* pos < 0 is invalid */
907 if (*pos < 0)
908 return NULL;
909
910 /* pos == 0 means header */
911 if (*pos == 0)
912 return SEQ_START_TOKEN;
913
914 /* Find the (pos-1)th ipc */
915 return sysvipc_find_ipc(ids, *pos - 1, pos);
916 }
917
918 static void sysvipc_proc_stop(struct seq_file *s, void *it)
919 {
920 struct kern_ipc_perm *ipc = it;
921 struct ipc_proc_iter *iter = s->private;
922 struct ipc_proc_iface *iface = iter->iface;
923 struct ipc_ids *ids;
924
925 /* If we had a locked structure, release it */
926 if (ipc && ipc != SEQ_START_TOKEN)
927 ipc_unlock(ipc);
928
929 ids = &iter->ns->ids[iface->ids];
930 /* Release the lock we took in start() */
931 up_read(&ids->rw_mutex);
932 }
933
934 static int sysvipc_proc_show(struct seq_file *s, void *it)
935 {
936 struct ipc_proc_iter *iter = s->private;
937 struct ipc_proc_iface *iface = iter->iface;
938
939 if (it == SEQ_START_TOKEN)
940 return seq_puts(s, iface->header);
941
942 return iface->show(s, it);
943 }
944
945 static const struct seq_operations sysvipc_proc_seqops = {
946 .start = sysvipc_proc_start,
947 .stop = sysvipc_proc_stop,
948 .next = sysvipc_proc_next,
949 .show = sysvipc_proc_show,
950 };
951
952 static int sysvipc_proc_open(struct inode *inode, struct file *file)
953 {
954 int ret;
955 struct seq_file *seq;
956 struct ipc_proc_iter *iter;
957
958 ret = -ENOMEM;
959 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
960 if (!iter)
961 goto out;
962
963 ret = seq_open(file, &sysvipc_proc_seqops);
964 if (ret)
965 goto out_kfree;
966
967 seq = file->private_data;
968 seq->private = iter;
969
970 iter->iface = PDE(inode)->data;
971 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
972 out:
973 return ret;
974 out_kfree:
975 kfree(iter);
976 goto out;
977 }
978
979 static int sysvipc_proc_release(struct inode *inode, struct file *file)
980 {
981 struct seq_file *seq = file->private_data;
982 struct ipc_proc_iter *iter = seq->private;
983 put_ipc_ns(iter->ns);
984 return seq_release_private(inode, file);
985 }
986
987 static const struct file_operations sysvipc_proc_fops = {
988 .open = sysvipc_proc_open,
989 .read = seq_read,
990 .llseek = seq_lseek,
991 .release = sysvipc_proc_release,
992 };
993 #endif /* CONFIG_PROC_FS */