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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
43struct 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
52static void ipc_memory_notifier(struct work_struct *work)
53{
54 ipcns_notify(IPCNS_MEMCHANGED);
55}
56
57static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
58
59
60static 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
100static 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
119void 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
137static 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 */
145void __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
181static 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
212int 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
250int 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 */
298static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
299 struct ipc_ops *ops, struct ipc_params *params)
300{
301 int err;
302retry:
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 * @ns: IPC namespace
321 * @ipcp: ipc permission set
322 * @ops: the actual security routine to call
323 * @params: its parameters
324 *
325 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
326 * when the key is not IPC_PRIVATE and that key already exists in the
327 * ids IDR.
328 *
329 * On success, the IPC id is returned.
330 *
331 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
332 */
333static int ipc_check_perms(struct ipc_namespace *ns,
334 struct kern_ipc_perm *ipcp,
335 struct ipc_ops *ops,
336 struct ipc_params *params)
337{
338 int err;
339
340 if (ipcperms(ns, ipcp, params->flg))
341 err = -EACCES;
342 else {
343 err = ops->associate(ipcp, params->flg);
344 if (!err)
345 err = ipcp->id;
346 }
347
348 return err;
349}
350
351/**
352 * ipcget_public - get an ipc object or create a new one
353 * @ns: namespace
354 * @ids: IPC identifer set
355 * @ops: the actual creation routine to call
356 * @params: its parameters
357 *
358 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
359 * when the key is not IPC_PRIVATE.
360 * It adds a new entry if the key is not found and does some permission
361 * / security checkings if the key is found.
362 *
363 * On success, the ipc id is returned.
364 */
365static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
366 struct ipc_ops *ops, struct ipc_params *params)
367{
368 struct kern_ipc_perm *ipcp;
369 int flg = params->flg;
370 int err;
371retry:
372 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
373
374 /*
375 * Take the lock as a writer since we are potentially going to add
376 * a new entry + read locks are not "upgradable"
377 */
378 down_write(&ids->rw_mutex);
379 ipcp = ipc_findkey(ids, params->key);
380 if (ipcp == NULL) {
381 /* key not used */
382 if (!(flg & IPC_CREAT))
383 err = -ENOENT;
384 else if (!err)
385 err = -ENOMEM;
386 else
387 err = ops->getnew(ns, params);
388 } else {
389 /* ipc object has been locked by ipc_findkey() */
390
391 if (flg & IPC_CREAT && flg & IPC_EXCL)
392 err = -EEXIST;
393 else {
394 err = 0;
395 if (ops->more_checks)
396 err = ops->more_checks(ipcp, params);
397 if (!err)
398 /*
399 * ipc_check_perms returns the IPC id on
400 * success
401 */
402 err = ipc_check_perms(ns, ipcp, ops, params);
403 }
404 ipc_unlock(ipcp);
405 }
406 up_write(&ids->rw_mutex);
407
408 if (err == -EAGAIN)
409 goto retry;
410
411 return err;
412}
413
414
415/**
416 * ipc_rmid - remove an IPC identifier
417 * @ids: IPC identifier set
418 * @ipcp: ipc perm structure containing the identifier to remove
419 *
420 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
421 * before this function is called, and remain locked on the exit.
422 */
423
424void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
425{
426 int lid = ipcid_to_idx(ipcp->id);
427
428 idr_remove(&ids->ipcs_idr, lid);
429
430 ids->in_use--;
431
432 ipcp->deleted = 1;
433
434 return;
435}
436
437/**
438 * ipc_alloc - allocate ipc space
439 * @size: size desired
440 *
441 * Allocate memory from the appropriate pools and return a pointer to it.
442 * NULL is returned if the allocation fails
443 */
444
445void* ipc_alloc(int size)
446{
447 void* out;
448 if(size > PAGE_SIZE)
449 out = vmalloc(size);
450 else
451 out = kmalloc(size, GFP_KERNEL);
452 return out;
453}
454
455/**
456 * ipc_free - free ipc space
457 * @ptr: pointer returned by ipc_alloc
458 * @size: size of block
459 *
460 * Free a block created with ipc_alloc(). The caller must know the size
461 * used in the allocation call.
462 */
463
464void ipc_free(void* ptr, int size)
465{
466 if(size > PAGE_SIZE)
467 vfree(ptr);
468 else
469 kfree(ptr);
470}
471
472/*
473 * rcu allocations:
474 * There are three headers that are prepended to the actual allocation:
475 * - during use: ipc_rcu_hdr.
476 * - during the rcu grace period: ipc_rcu_grace.
477 * - [only if vmalloc]: ipc_rcu_sched.
478 * Their lifetime doesn't overlap, thus the headers share the same memory.
479 * Unlike a normal union, they are right-aligned, thus some container_of
480 * forward/backward casting is necessary:
481 */
482struct ipc_rcu_hdr
483{
484 int refcount;
485 int is_vmalloc;
486 void *data[0];
487};
488
489
490struct ipc_rcu_grace
491{
492 struct rcu_head rcu;
493 /* "void *" makes sure alignment of following data is sane. */
494 void *data[0];
495};
496
497struct ipc_rcu_sched
498{
499 struct work_struct work;
500 /* "void *" makes sure alignment of following data is sane. */
501 void *data[0];
502};
503
504#define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
505 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
506#define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
507 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
508
509static inline int rcu_use_vmalloc(int size)
510{
511 /* Too big for a single page? */
512 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
513 return 1;
514 return 0;
515}
516
517/**
518 * ipc_rcu_alloc - allocate ipc and rcu space
519 * @size: size desired
520 *
521 * Allocate memory for the rcu header structure + the object.
522 * Returns the pointer to the object.
523 * NULL is returned if the allocation fails.
524 */
525
526void* ipc_rcu_alloc(int size)
527{
528 void* out;
529 /*
530 * We prepend the allocation with the rcu struct, and
531 * workqueue if necessary (for vmalloc).
532 */
533 if (rcu_use_vmalloc(size)) {
534 out = vmalloc(HDRLEN_VMALLOC + size);
535 if (out) {
536 out += HDRLEN_VMALLOC;
537 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
538 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
539 }
540 } else {
541 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
542 if (out) {
543 out += HDRLEN_KMALLOC;
544 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
545 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
546 }
547 }
548
549 return out;
550}
551
552void ipc_rcu_getref(void *ptr)
553{
554 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
555}
556
557static void ipc_do_vfree(struct work_struct *work)
558{
559 vfree(container_of(work, struct ipc_rcu_sched, work));
560}
561
562/**
563 * ipc_schedule_free - free ipc + rcu space
564 * @head: RCU callback structure for queued work
565 *
566 * Since RCU callback function is called in bh,
567 * we need to defer the vfree to schedule_work().
568 */
569static void ipc_schedule_free(struct rcu_head *head)
570{
571 struct ipc_rcu_grace *grace;
572 struct ipc_rcu_sched *sched;
573
574 grace = container_of(head, struct ipc_rcu_grace, rcu);
575 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
576 data[0]);
577
578 INIT_WORK(&sched->work, ipc_do_vfree);
579 schedule_work(&sched->work);
580}
581
582void ipc_rcu_putref(void *ptr)
583{
584 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
585 return;
586
587 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
588 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
589 ipc_schedule_free);
590 } else {
591 kfree_rcu(container_of(ptr, struct ipc_rcu_grace, data), rcu);
592 }
593}
594
595/**
596 * ipcperms - check IPC permissions
597 * @ns: IPC namespace
598 * @ipcp: IPC permission set
599 * @flag: desired permission set.
600 *
601 * Check user, group, other permissions for access
602 * to ipc resources. return 0 if allowed
603 *
604 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
605 */
606
607int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
608{
609 uid_t euid = current_euid();
610 int requested_mode, granted_mode;
611
612 audit_ipc_obj(ipcp);
613 requested_mode = (flag >> 6) | (flag >> 3) | flag;
614 granted_mode = ipcp->mode;
615 if (euid == ipcp->cuid ||
616 euid == ipcp->uid)
617 granted_mode >>= 6;
618 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
619 granted_mode >>= 3;
620 /* is there some bit set in requested_mode but not in granted_mode? */
621 if ((requested_mode & ~granted_mode & 0007) &&
622 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
623 return -1;
624
625 return security_ipc_permission(ipcp, flag);
626}
627
628/*
629 * Functions to convert between the kern_ipc_perm structure and the
630 * old/new ipc_perm structures
631 */
632
633/**
634 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
635 * @in: kernel permissions
636 * @out: new style IPC permissions
637 *
638 * Turn the kernel object @in into a set of permissions descriptions
639 * for returning to userspace (@out).
640 */
641
642
643void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
644{
645 out->key = in->key;
646 out->uid = in->uid;
647 out->gid = in->gid;
648 out->cuid = in->cuid;
649 out->cgid = in->cgid;
650 out->mode = in->mode;
651 out->seq = in->seq;
652}
653
654/**
655 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
656 * @in: new style IPC permissions
657 * @out: old style IPC permissions
658 *
659 * Turn the new style permissions object @in into a compatibility
660 * object and store it into the @out pointer.
661 */
662
663void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
664{
665 out->key = in->key;
666 SET_UID(out->uid, in->uid);
667 SET_GID(out->gid, in->gid);
668 SET_UID(out->cuid, in->cuid);
669 SET_GID(out->cgid, in->cgid);
670 out->mode = in->mode;
671 out->seq = in->seq;
672}
673
674/**
675 * ipc_lock - Lock an ipc structure without rw_mutex held
676 * @ids: IPC identifier set
677 * @id: ipc id to look for
678 *
679 * Look for an id in the ipc ids idr and lock the associated ipc object.
680 *
681 * The ipc object is locked on exit.
682 */
683
684struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
685{
686 struct kern_ipc_perm *out;
687 int lid = ipcid_to_idx(id);
688
689 rcu_read_lock();
690 out = idr_find(&ids->ipcs_idr, lid);
691 if (out == NULL) {
692 rcu_read_unlock();
693 return ERR_PTR(-EINVAL);
694 }
695
696 spin_lock(&out->lock);
697
698 /* ipc_rmid() may have already freed the ID while ipc_lock
699 * was spinning: here verify that the structure is still valid
700 */
701 if (out->deleted) {
702 spin_unlock(&out->lock);
703 rcu_read_unlock();
704 return ERR_PTR(-EINVAL);
705 }
706
707 return out;
708}
709
710struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
711{
712 struct kern_ipc_perm *out;
713
714 out = ipc_lock(ids, id);
715 if (IS_ERR(out))
716 return out;
717
718 if (ipc_checkid(out, id)) {
719 ipc_unlock(out);
720 return ERR_PTR(-EIDRM);
721 }
722
723 return out;
724}
725
726/**
727 * ipcget - Common sys_*get() code
728 * @ns : namsepace
729 * @ids : IPC identifier set
730 * @ops : operations to be called on ipc object creation, permission checks
731 * and further checks
732 * @params : the parameters needed by the previous operations.
733 *
734 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
735 */
736int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
737 struct ipc_ops *ops, struct ipc_params *params)
738{
739 if (params->key == IPC_PRIVATE)
740 return ipcget_new(ns, ids, ops, params);
741 else
742 return ipcget_public(ns, ids, ops, params);
743}
744
745/**
746 * ipc_update_perm - update the permissions of an IPC.
747 * @in: the permission given as input.
748 * @out: the permission of the ipc to set.
749 */
750void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
751{
752 out->uid = in->uid;
753 out->gid = in->gid;
754 out->mode = (out->mode & ~S_IRWXUGO)
755 | (in->mode & S_IRWXUGO);
756}
757
758/**
759 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
760 * @ns: the ipc namespace
761 * @ids: the table of ids where to look for the ipc
762 * @id: the id of the ipc to retrieve
763 * @cmd: the cmd to check
764 * @perm: the permission to set
765 * @extra_perm: one extra permission parameter used by msq
766 *
767 * This function does some common audit and permissions check for some IPC_XXX
768 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
769 * It must be called without any lock held and
770 * - retrieves the ipc with the given id in the given table.
771 * - performs some audit and permission check, depending on the given cmd
772 * - returns the ipc with both ipc and rw_mutex locks held in case of success
773 * or an err-code without any lock held otherwise.
774 */
775struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
776 struct ipc_ids *ids, int id, int cmd,
777 struct ipc64_perm *perm, int extra_perm)
778{
779 struct kern_ipc_perm *ipcp;
780 uid_t euid;
781 int err;
782
783 down_write(&ids->rw_mutex);
784 ipcp = ipc_lock_check(ids, id);
785 if (IS_ERR(ipcp)) {
786 err = PTR_ERR(ipcp);
787 goto out_up;
788 }
789
790 audit_ipc_obj(ipcp);
791 if (cmd == IPC_SET)
792 audit_ipc_set_perm(extra_perm, perm->uid,
793 perm->gid, perm->mode);
794
795 euid = current_euid();
796 if (euid == ipcp->cuid || euid == ipcp->uid ||
797 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
798 return ipcp;
799
800 err = -EPERM;
801 ipc_unlock(ipcp);
802out_up:
803 up_write(&ids->rw_mutex);
804 return ERR_PTR(err);
805}
806
807#ifdef __ARCH_WANT_IPC_PARSE_VERSION
808
809
810/**
811 * ipc_parse_version - IPC call version
812 * @cmd: pointer to command
813 *
814 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
815 * The @cmd value is turned from an encoding command and version into
816 * just the command code.
817 */
818
819int ipc_parse_version (int *cmd)
820{
821 if (*cmd & IPC_64) {
822 *cmd ^= IPC_64;
823 return IPC_64;
824 } else {
825 return IPC_OLD;
826 }
827}
828
829#endif /* __ARCH_WANT_IPC_PARSE_VERSION */
830
831#ifdef CONFIG_PROC_FS
832struct ipc_proc_iter {
833 struct ipc_namespace *ns;
834 struct ipc_proc_iface *iface;
835};
836
837/*
838 * This routine locks the ipc structure found at least at position pos.
839 */
840static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
841 loff_t *new_pos)
842{
843 struct kern_ipc_perm *ipc;
844 int total, id;
845
846 total = 0;
847 for (id = 0; id < pos && total < ids->in_use; id++) {
848 ipc = idr_find(&ids->ipcs_idr, id);
849 if (ipc != NULL)
850 total++;
851 }
852
853 if (total >= ids->in_use)
854 return NULL;
855
856 for ( ; pos < IPCMNI; pos++) {
857 ipc = idr_find(&ids->ipcs_idr, pos);
858 if (ipc != NULL) {
859 *new_pos = pos + 1;
860 ipc_lock_by_ptr(ipc);
861 return ipc;
862 }
863 }
864
865 /* Out of range - return NULL to terminate iteration */
866 return NULL;
867}
868
869static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
870{
871 struct ipc_proc_iter *iter = s->private;
872 struct ipc_proc_iface *iface = iter->iface;
873 struct kern_ipc_perm *ipc = it;
874
875 /* If we had an ipc id locked before, unlock it */
876 if (ipc && ipc != SEQ_START_TOKEN)
877 ipc_unlock(ipc);
878
879 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
880}
881
882/*
883 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
884 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
885 */
886static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
887{
888 struct ipc_proc_iter *iter = s->private;
889 struct ipc_proc_iface *iface = iter->iface;
890 struct ipc_ids *ids;
891
892 ids = &iter->ns->ids[iface->ids];
893
894 /*
895 * Take the lock - this will be released by the corresponding
896 * call to stop().
897 */
898 down_read(&ids->rw_mutex);
899
900 /* pos < 0 is invalid */
901 if (*pos < 0)
902 return NULL;
903
904 /* pos == 0 means header */
905 if (*pos == 0)
906 return SEQ_START_TOKEN;
907
908 /* Find the (pos-1)th ipc */
909 return sysvipc_find_ipc(ids, *pos - 1, pos);
910}
911
912static void sysvipc_proc_stop(struct seq_file *s, void *it)
913{
914 struct kern_ipc_perm *ipc = it;
915 struct ipc_proc_iter *iter = s->private;
916 struct ipc_proc_iface *iface = iter->iface;
917 struct ipc_ids *ids;
918
919 /* If we had a locked structure, release it */
920 if (ipc && ipc != SEQ_START_TOKEN)
921 ipc_unlock(ipc);
922
923 ids = &iter->ns->ids[iface->ids];
924 /* Release the lock we took in start() */
925 up_read(&ids->rw_mutex);
926}
927
928static int sysvipc_proc_show(struct seq_file *s, void *it)
929{
930 struct ipc_proc_iter *iter = s->private;
931 struct ipc_proc_iface *iface = iter->iface;
932
933 if (it == SEQ_START_TOKEN)
934 return seq_puts(s, iface->header);
935
936 return iface->show(s, it);
937}
938
939static const struct seq_operations sysvipc_proc_seqops = {
940 .start = sysvipc_proc_start,
941 .stop = sysvipc_proc_stop,
942 .next = sysvipc_proc_next,
943 .show = sysvipc_proc_show,
944};
945
946static int sysvipc_proc_open(struct inode *inode, struct file *file)
947{
948 int ret;
949 struct seq_file *seq;
950 struct ipc_proc_iter *iter;
951
952 ret = -ENOMEM;
953 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
954 if (!iter)
955 goto out;
956
957 ret = seq_open(file, &sysvipc_proc_seqops);
958 if (ret)
959 goto out_kfree;
960
961 seq = file->private_data;
962 seq->private = iter;
963
964 iter->iface = PDE(inode)->data;
965 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
966out:
967 return ret;
968out_kfree:
969 kfree(iter);
970 goto out;
971}
972
973static int sysvipc_proc_release(struct inode *inode, struct file *file)
974{
975 struct seq_file *seq = file->private_data;
976 struct ipc_proc_iter *iter = seq->private;
977 put_ipc_ns(iter->ns);
978 return seq_release_private(inode, file);
979}
980
981static const struct file_operations sysvipc_proc_fops = {
982 .open = sysvipc_proc_open,
983 .read = seq_read,
984 .llseek = seq_lseek,
985 .release = sysvipc_proc_release,
986};
987#endif /* CONFIG_PROC_FS */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/util.c
4 * Copyright (C) 1992 Krishna Balasubramanian
5 *
6 * Sep 1997 - Call suser() last after "normal" permission checks so we
7 * get BSD style process accounting right.
8 * Occurs in several places in the IPC code.
9 * Chris Evans, <chris@ferret.lmh.ox.ac.uk>
10 * Nov 1999 - ipc helper functions, unified SMP locking
11 * Manfred Spraul <manfred@colorfullife.com>
12 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
13 * Mingming Cao <cmm@us.ibm.com>
14 * Mar 2006 - support for audit of ipc object properties
15 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
16 * Jun 2006 - namespaces ssupport
17 * OpenVZ, SWsoft Inc.
18 * Pavel Emelianov <xemul@openvz.org>
19 *
20 * General sysv ipc locking scheme:
21 * rcu_read_lock()
22 * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
23 * tree.
24 * - perform initial checks (capabilities, auditing and permission,
25 * etc).
26 * - perform read-only operations, such as INFO command, that
27 * do not demand atomicity
28 * acquire the ipc lock (kern_ipc_perm.lock) through
29 * ipc_lock_object()
30 * - perform read-only operations that demand atomicity,
31 * such as STAT command.
32 * - perform data updates, such as SET, RMID commands and
33 * mechanism-specific operations (semop/semtimedop,
34 * msgsnd/msgrcv, shmat/shmdt).
35 * drop the ipc lock, through ipc_unlock_object().
36 * rcu_read_unlock()
37 *
38 * The ids->rwsem must be taken when:
39 * - creating, removing and iterating the existing entries in ipc
40 * identifier sets.
41 * - iterating through files under /proc/sysvipc/
42 *
43 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
44 * see sem_lock().
45 */
46
47#include <linux/mm.h>
48#include <linux/shm.h>
49#include <linux/init.h>
50#include <linux/msg.h>
51#include <linux/vmalloc.h>
52#include <linux/slab.h>
53#include <linux/notifier.h>
54#include <linux/capability.h>
55#include <linux/highuid.h>
56#include <linux/security.h>
57#include <linux/rcupdate.h>
58#include <linux/workqueue.h>
59#include <linux/seq_file.h>
60#include <linux/proc_fs.h>
61#include <linux/audit.h>
62#include <linux/nsproxy.h>
63#include <linux/rwsem.h>
64#include <linux/memory.h>
65#include <linux/ipc_namespace.h>
66
67#include <asm/unistd.h>
68
69#include "util.h"
70
71struct ipc_proc_iface {
72 const char *path;
73 const char *header;
74 int ids;
75 int (*show)(struct seq_file *, void *);
76};
77
78/**
79 * ipc_init - initialise ipc subsystem
80 *
81 * The various sysv ipc resources (semaphores, messages and shared
82 * memory) are initialised.
83 *
84 * A callback routine is registered into the memory hotplug notifier
85 * chain: since msgmni scales to lowmem this callback routine will be
86 * called upon successful memory add / remove to recompute msmgni.
87 */
88static int __init ipc_init(void)
89{
90 int err_sem, err_msg;
91
92 proc_mkdir("sysvipc", NULL);
93 err_sem = sem_init();
94 WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem);
95 err_msg = msg_init();
96 WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg);
97 shm_init();
98
99 return err_msg ? err_msg : err_sem;
100}
101device_initcall(ipc_init);
102
103static const struct rhashtable_params ipc_kht_params = {
104 .head_offset = offsetof(struct kern_ipc_perm, khtnode),
105 .key_offset = offsetof(struct kern_ipc_perm, key),
106 .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key),
107 .locks_mul = 1,
108 .automatic_shrinking = true,
109};
110
111/**
112 * ipc_init_ids - initialise ipc identifiers
113 * @ids: ipc identifier set
114 *
115 * Set up the sequence range to use for the ipc identifier range (limited
116 * below IPCMNI) then initialise the keys hashtable and ids idr.
117 */
118int ipc_init_ids(struct ipc_ids *ids)
119{
120 int err;
121 ids->in_use = 0;
122 ids->seq = 0;
123 init_rwsem(&ids->rwsem);
124 err = rhashtable_init(&ids->key_ht, &ipc_kht_params);
125 if (err)
126 return err;
127 idr_init(&ids->ipcs_idr);
128 ids->tables_initialized = true;
129 ids->max_id = -1;
130#ifdef CONFIG_CHECKPOINT_RESTORE
131 ids->next_id = -1;
132#endif
133 return 0;
134}
135
136#ifdef CONFIG_PROC_FS
137static 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 */
145void __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#endif
168
169/**
170 * ipc_findkey - find a key in an ipc identifier set
171 * @ids: ipc identifier set
172 * @key: key to find
173 *
174 * Returns the locked pointer to the ipc structure if found or NULL
175 * otherwise. If key is found ipc points to the owning ipc structure
176 *
177 * Called with writer ipc_ids.rwsem held.
178 */
179static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
180{
181 struct kern_ipc_perm *ipcp = NULL;
182
183 if (likely(ids->tables_initialized))
184 ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
185 ipc_kht_params);
186
187 if (ipcp) {
188 rcu_read_lock();
189 ipc_lock_object(ipcp);
190 return ipcp;
191 }
192
193 return NULL;
194}
195
196#ifdef CONFIG_CHECKPOINT_RESTORE
197/*
198 * Specify desired id for next allocated IPC object.
199 */
200#define ipc_idr_alloc(ids, new) \
201 idr_alloc(&(ids)->ipcs_idr, (new), \
202 (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\
203 0, GFP_NOWAIT)
204
205static inline int ipc_buildid(int id, struct ipc_ids *ids,
206 struct kern_ipc_perm *new)
207{
208 if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */
209 new->seq = ids->seq++;
210 if (ids->seq > IPCID_SEQ_MAX)
211 ids->seq = 0;
212 } else {
213 new->seq = ipcid_to_seqx(ids->next_id);
214 ids->next_id = -1;
215 }
216
217 return SEQ_MULTIPLIER * new->seq + id;
218}
219
220#else
221#define ipc_idr_alloc(ids, new) \
222 idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT)
223
224static inline int ipc_buildid(int id, struct ipc_ids *ids,
225 struct kern_ipc_perm *new)
226{
227 new->seq = ids->seq++;
228 if (ids->seq > IPCID_SEQ_MAX)
229 ids->seq = 0;
230
231 return SEQ_MULTIPLIER * new->seq + id;
232}
233
234#endif /* CONFIG_CHECKPOINT_RESTORE */
235
236/**
237 * ipc_addid - add an ipc identifier
238 * @ids: ipc identifier set
239 * @new: new ipc permission set
240 * @limit: 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 writer ipc_ids.rwsem held.
248 */
249int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
250{
251 kuid_t euid;
252 kgid_t egid;
253 int id, err;
254
255 if (limit > IPCMNI)
256 limit = IPCMNI;
257
258 if (!ids->tables_initialized || ids->in_use >= limit)
259 return -ENOSPC;
260
261 idr_preload(GFP_KERNEL);
262
263 refcount_set(&new->refcount, 1);
264 spin_lock_init(&new->lock);
265 new->deleted = false;
266 rcu_read_lock();
267 spin_lock(&new->lock);
268
269 current_euid_egid(&euid, &egid);
270 new->cuid = new->uid = euid;
271 new->gid = new->cgid = egid;
272
273 id = ipc_idr_alloc(ids, new);
274 idr_preload_end();
275
276 if (id >= 0 && new->key != IPC_PRIVATE) {
277 err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
278 ipc_kht_params);
279 if (err < 0) {
280 idr_remove(&ids->ipcs_idr, id);
281 id = err;
282 }
283 }
284 if (id < 0) {
285 spin_unlock(&new->lock);
286 rcu_read_unlock();
287 return id;
288 }
289
290 ids->in_use++;
291 if (id > ids->max_id)
292 ids->max_id = id;
293
294 new->id = ipc_buildid(id, ids, new);
295
296 return id;
297}
298
299/**
300 * ipcget_new - create a new ipc object
301 * @ns: ipc namespace
302 * @ids: ipc identifier set
303 * @ops: the actual creation routine to call
304 * @params: its parameters
305 *
306 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
307 * when the key is IPC_PRIVATE.
308 */
309static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
310 const struct ipc_ops *ops, struct ipc_params *params)
311{
312 int err;
313
314 down_write(&ids->rwsem);
315 err = ops->getnew(ns, params);
316 up_write(&ids->rwsem);
317 return err;
318}
319
320/**
321 * ipc_check_perms - check security and permissions for an ipc object
322 * @ns: ipc namespace
323 * @ipcp: ipc permission set
324 * @ops: the actual security routine to call
325 * @params: its parameters
326 *
327 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
328 * when the key is not IPC_PRIVATE and that key already exists in the
329 * ds IDR.
330 *
331 * On success, the ipc id is returned.
332 *
333 * It is called with ipc_ids.rwsem and ipcp->lock held.
334 */
335static int ipc_check_perms(struct ipc_namespace *ns,
336 struct kern_ipc_perm *ipcp,
337 const struct ipc_ops *ops,
338 struct ipc_params *params)
339{
340 int err;
341
342 if (ipcperms(ns, ipcp, params->flg))
343 err = -EACCES;
344 else {
345 err = ops->associate(ipcp, params->flg);
346 if (!err)
347 err = ipcp->id;
348 }
349
350 return err;
351}
352
353/**
354 * ipcget_public - get an ipc object or create a new one
355 * @ns: ipc namespace
356 * @ids: ipc identifier set
357 * @ops: the actual creation routine to call
358 * @params: its parameters
359 *
360 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
361 * when the key is not IPC_PRIVATE.
362 * It adds a new entry if the key is not found and does some permission
363 * / security checkings if the key is found.
364 *
365 * On success, the ipc id is returned.
366 */
367static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
368 const struct ipc_ops *ops, struct ipc_params *params)
369{
370 struct kern_ipc_perm *ipcp;
371 int flg = params->flg;
372 int err;
373
374 /*
375 * Take the lock as a writer since we are potentially going to add
376 * a new entry + read locks are not "upgradable"
377 */
378 down_write(&ids->rwsem);
379 ipcp = ipc_findkey(ids, params->key);
380 if (ipcp == NULL) {
381 /* key not used */
382 if (!(flg & IPC_CREAT))
383 err = -ENOENT;
384 else
385 err = ops->getnew(ns, params);
386 } else {
387 /* ipc object has been locked by ipc_findkey() */
388
389 if (flg & IPC_CREAT && flg & IPC_EXCL)
390 err = -EEXIST;
391 else {
392 err = 0;
393 if (ops->more_checks)
394 err = ops->more_checks(ipcp, params);
395 if (!err)
396 /*
397 * ipc_check_perms returns the IPC id on
398 * success
399 */
400 err = ipc_check_perms(ns, ipcp, ops, params);
401 }
402 ipc_unlock(ipcp);
403 }
404 up_write(&ids->rwsem);
405
406 return err;
407}
408
409/**
410 * ipc_kht_remove - remove an ipc from the key hashtable
411 * @ids: ipc identifier set
412 * @ipcp: ipc perm structure containing the key to remove
413 *
414 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
415 * before this function is called, and remain locked on the exit.
416 */
417static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
418{
419 if (ipcp->key != IPC_PRIVATE)
420 rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
421 ipc_kht_params);
422}
423
424/**
425 * ipc_rmid - remove an ipc identifier
426 * @ids: ipc identifier set
427 * @ipcp: ipc perm structure containing the identifier to remove
428 *
429 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
430 * before this function is called, and remain locked on the exit.
431 */
432void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
433{
434 int lid = ipcid_to_idx(ipcp->id);
435
436 idr_remove(&ids->ipcs_idr, lid);
437 ipc_kht_remove(ids, ipcp);
438 ids->in_use--;
439 ipcp->deleted = true;
440
441 if (unlikely(lid == ids->max_id)) {
442 do {
443 lid--;
444 if (lid == -1)
445 break;
446 } while (!idr_find(&ids->ipcs_idr, lid));
447 ids->max_id = lid;
448 }
449}
450
451/**
452 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
453 * @ids: ipc identifier set
454 * @ipcp: ipc perm structure containing the key to modify
455 *
456 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
457 * before this function is called, and remain locked on the exit.
458 */
459void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
460{
461 ipc_kht_remove(ids, ipcp);
462 ipcp->key = IPC_PRIVATE;
463}
464
465int ipc_rcu_getref(struct kern_ipc_perm *ptr)
466{
467 return refcount_inc_not_zero(&ptr->refcount);
468}
469
470void ipc_rcu_putref(struct kern_ipc_perm *ptr,
471 void (*func)(struct rcu_head *head))
472{
473 if (!refcount_dec_and_test(&ptr->refcount))
474 return;
475
476 call_rcu(&ptr->rcu, func);
477}
478
479/**
480 * ipcperms - check ipc permissions
481 * @ns: ipc namespace
482 * @ipcp: ipc permission set
483 * @flag: desired permission set
484 *
485 * Check user, group, other permissions for access
486 * to ipc resources. return 0 if allowed
487 *
488 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
489 */
490int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
491{
492 kuid_t euid = current_euid();
493 int requested_mode, granted_mode;
494
495 audit_ipc_obj(ipcp);
496 requested_mode = (flag >> 6) | (flag >> 3) | flag;
497 granted_mode = ipcp->mode;
498 if (uid_eq(euid, ipcp->cuid) ||
499 uid_eq(euid, ipcp->uid))
500 granted_mode >>= 6;
501 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
502 granted_mode >>= 3;
503 /* is there some bit set in requested_mode but not in granted_mode? */
504 if ((requested_mode & ~granted_mode & 0007) &&
505 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
506 return -1;
507
508 return security_ipc_permission(ipcp, flag);
509}
510
511/*
512 * Functions to convert between the kern_ipc_perm structure and the
513 * old/new ipc_perm structures
514 */
515
516/**
517 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
518 * @in: kernel permissions
519 * @out: new style ipc permissions
520 *
521 * Turn the kernel object @in into a set of permissions descriptions
522 * for returning to userspace (@out).
523 */
524void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
525{
526 out->key = in->key;
527 out->uid = from_kuid_munged(current_user_ns(), in->uid);
528 out->gid = from_kgid_munged(current_user_ns(), in->gid);
529 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
530 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
531 out->mode = in->mode;
532 out->seq = in->seq;
533}
534
535/**
536 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
537 * @in: new style ipc permissions
538 * @out: old style ipc permissions
539 *
540 * Turn the new style permissions object @in into a compatibility
541 * object and store it into the @out pointer.
542 */
543void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
544{
545 out->key = in->key;
546 SET_UID(out->uid, in->uid);
547 SET_GID(out->gid, in->gid);
548 SET_UID(out->cuid, in->cuid);
549 SET_GID(out->cgid, in->cgid);
550 out->mode = in->mode;
551 out->seq = in->seq;
552}
553
554/**
555 * ipc_obtain_object_idr
556 * @ids: ipc identifier set
557 * @id: ipc id to look for
558 *
559 * Look for an id in the ipc ids idr and return associated ipc object.
560 *
561 * Call inside the RCU critical section.
562 * The ipc object is *not* locked on exit.
563 */
564struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
565{
566 struct kern_ipc_perm *out;
567 int lid = ipcid_to_idx(id);
568
569 if (unlikely(!ids->tables_initialized))
570 return ERR_PTR(-EINVAL);
571
572 out = idr_find(&ids->ipcs_idr, lid);
573 if (!out)
574 return ERR_PTR(-EINVAL);
575
576 return out;
577}
578
579/**
580 * ipc_lock - lock an ipc structure without rwsem held
581 * @ids: ipc identifier set
582 * @id: ipc id to look for
583 *
584 * Look for an id in the ipc ids idr and lock the associated ipc object.
585 *
586 * The ipc object is locked on successful exit.
587 */
588struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
589{
590 struct kern_ipc_perm *out;
591
592 rcu_read_lock();
593 out = ipc_obtain_object_idr(ids, id);
594 if (IS_ERR(out))
595 goto err;
596
597 spin_lock(&out->lock);
598
599 /*
600 * ipc_rmid() may have already freed the ID while ipc_lock()
601 * was spinning: here verify that the structure is still valid.
602 * Upon races with RMID, return -EIDRM, thus indicating that
603 * the ID points to a removed identifier.
604 */
605 if (ipc_valid_object(out))
606 return out;
607
608 spin_unlock(&out->lock);
609 out = ERR_PTR(-EIDRM);
610err:
611 rcu_read_unlock();
612 return out;
613}
614
615/**
616 * ipc_obtain_object_check
617 * @ids: ipc identifier set
618 * @id: ipc id to look for
619 *
620 * Similar to ipc_obtain_object_idr() but also checks
621 * the ipc object reference counter.
622 *
623 * Call inside the RCU critical section.
624 * The ipc object is *not* locked on exit.
625 */
626struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
627{
628 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
629
630 if (IS_ERR(out))
631 goto out;
632
633 if (ipc_checkid(out, id))
634 return ERR_PTR(-EINVAL);
635out:
636 return out;
637}
638
639/**
640 * ipcget - Common sys_*get() code
641 * @ns: namespace
642 * @ids: ipc identifier set
643 * @ops: operations to be called on ipc object creation, permission checks
644 * and further checks
645 * @params: the parameters needed by the previous operations.
646 *
647 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
648 */
649int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
650 const struct ipc_ops *ops, struct ipc_params *params)
651{
652 if (params->key == IPC_PRIVATE)
653 return ipcget_new(ns, ids, ops, params);
654 else
655 return ipcget_public(ns, ids, ops, params);
656}
657
658/**
659 * ipc_update_perm - update the permissions of an ipc object
660 * @in: the permission given as input.
661 * @out: the permission of the ipc to set.
662 */
663int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
664{
665 kuid_t uid = make_kuid(current_user_ns(), in->uid);
666 kgid_t gid = make_kgid(current_user_ns(), in->gid);
667 if (!uid_valid(uid) || !gid_valid(gid))
668 return -EINVAL;
669
670 out->uid = uid;
671 out->gid = gid;
672 out->mode = (out->mode & ~S_IRWXUGO)
673 | (in->mode & S_IRWXUGO);
674
675 return 0;
676}
677
678/**
679 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
680 * @ns: ipc namespace
681 * @ids: the table of ids where to look for the ipc
682 * @id: the id of the ipc to retrieve
683 * @cmd: the cmd to check
684 * @perm: the permission to set
685 * @extra_perm: one extra permission parameter used by msq
686 *
687 * This function does some common audit and permissions check for some IPC_XXX
688 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
689 * It must be called without any lock held and:
690 *
691 * - retrieves the ipc with the given id in the given table.
692 * - performs some audit and permission check, depending on the given cmd
693 * - returns a pointer to the ipc object or otherwise, the corresponding
694 * error.
695 *
696 * Call holding the both the rwsem and the rcu read lock.
697 */
698struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
699 struct ipc_ids *ids, int id, int cmd,
700 struct ipc64_perm *perm, int extra_perm)
701{
702 kuid_t euid;
703 int err = -EPERM;
704 struct kern_ipc_perm *ipcp;
705
706 ipcp = ipc_obtain_object_check(ids, id);
707 if (IS_ERR(ipcp)) {
708 err = PTR_ERR(ipcp);
709 goto err;
710 }
711
712 audit_ipc_obj(ipcp);
713 if (cmd == IPC_SET)
714 audit_ipc_set_perm(extra_perm, perm->uid,
715 perm->gid, perm->mode);
716
717 euid = current_euid();
718 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
719 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
720 return ipcp; /* successful lookup */
721err:
722 return ERR_PTR(err);
723}
724
725#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
726
727
728/**
729 * ipc_parse_version - ipc call version
730 * @cmd: pointer to command
731 *
732 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
733 * The @cmd value is turned from an encoding command and version into
734 * just the command code.
735 */
736int ipc_parse_version(int *cmd)
737{
738 if (*cmd & IPC_64) {
739 *cmd ^= IPC_64;
740 return IPC_64;
741 } else {
742 return IPC_OLD;
743 }
744}
745
746#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
747
748#ifdef CONFIG_PROC_FS
749struct ipc_proc_iter {
750 struct ipc_namespace *ns;
751 struct pid_namespace *pid_ns;
752 struct ipc_proc_iface *iface;
753};
754
755struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
756{
757 struct ipc_proc_iter *iter = s->private;
758 return iter->pid_ns;
759}
760
761/*
762 * This routine locks the ipc structure found at least at position pos.
763 */
764static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
765 loff_t *new_pos)
766{
767 struct kern_ipc_perm *ipc;
768 int total, id;
769
770 total = 0;
771 for (id = 0; id < pos && total < ids->in_use; id++) {
772 ipc = idr_find(&ids->ipcs_idr, id);
773 if (ipc != NULL)
774 total++;
775 }
776
777 if (total >= ids->in_use)
778 return NULL;
779
780 for (; pos < IPCMNI; pos++) {
781 ipc = idr_find(&ids->ipcs_idr, pos);
782 if (ipc != NULL) {
783 *new_pos = pos + 1;
784 rcu_read_lock();
785 ipc_lock_object(ipc);
786 return ipc;
787 }
788 }
789
790 /* Out of range - return NULL to terminate iteration */
791 return NULL;
792}
793
794static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
795{
796 struct ipc_proc_iter *iter = s->private;
797 struct ipc_proc_iface *iface = iter->iface;
798 struct kern_ipc_perm *ipc = it;
799
800 /* If we had an ipc id locked before, unlock it */
801 if (ipc && ipc != SEQ_START_TOKEN)
802 ipc_unlock(ipc);
803
804 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
805}
806
807/*
808 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
809 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
810 */
811static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
812{
813 struct ipc_proc_iter *iter = s->private;
814 struct ipc_proc_iface *iface = iter->iface;
815 struct ipc_ids *ids;
816
817 ids = &iter->ns->ids[iface->ids];
818
819 /*
820 * Take the lock - this will be released by the corresponding
821 * call to stop().
822 */
823 down_read(&ids->rwsem);
824
825 /* pos < 0 is invalid */
826 if (*pos < 0)
827 return NULL;
828
829 /* pos == 0 means header */
830 if (*pos == 0)
831 return SEQ_START_TOKEN;
832
833 /* Find the (pos-1)th ipc */
834 return sysvipc_find_ipc(ids, *pos - 1, pos);
835}
836
837static void sysvipc_proc_stop(struct seq_file *s, void *it)
838{
839 struct kern_ipc_perm *ipc = it;
840 struct ipc_proc_iter *iter = s->private;
841 struct ipc_proc_iface *iface = iter->iface;
842 struct ipc_ids *ids;
843
844 /* If we had a locked structure, release it */
845 if (ipc && ipc != SEQ_START_TOKEN)
846 ipc_unlock(ipc);
847
848 ids = &iter->ns->ids[iface->ids];
849 /* Release the lock we took in start() */
850 up_read(&ids->rwsem);
851}
852
853static int sysvipc_proc_show(struct seq_file *s, void *it)
854{
855 struct ipc_proc_iter *iter = s->private;
856 struct ipc_proc_iface *iface = iter->iface;
857
858 if (it == SEQ_START_TOKEN) {
859 seq_puts(s, iface->header);
860 return 0;
861 }
862
863 return iface->show(s, it);
864}
865
866static const struct seq_operations sysvipc_proc_seqops = {
867 .start = sysvipc_proc_start,
868 .stop = sysvipc_proc_stop,
869 .next = sysvipc_proc_next,
870 .show = sysvipc_proc_show,
871};
872
873static int sysvipc_proc_open(struct inode *inode, struct file *file)
874{
875 struct ipc_proc_iter *iter;
876
877 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
878 if (!iter)
879 return -ENOMEM;
880
881 iter->iface = PDE_DATA(inode);
882 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
883 iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
884
885 return 0;
886}
887
888static int sysvipc_proc_release(struct inode *inode, struct file *file)
889{
890 struct seq_file *seq = file->private_data;
891 struct ipc_proc_iter *iter = seq->private;
892 put_ipc_ns(iter->ns);
893 put_pid_ns(iter->pid_ns);
894 return seq_release_private(inode, file);
895}
896
897static const struct file_operations sysvipc_proc_fops = {
898 .open = sysvipc_proc_open,
899 .read = seq_read,
900 .llseek = seq_lseek,
901 .release = sysvipc_proc_release,
902};
903#endif /* CONFIG_PROC_FS */