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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#include <linux/rhashtable.h>
67
68#include <asm/unistd.h>
69
70#include "util.h"
71
72struct ipc_proc_iface {
73 const char *path;
74 const char *header;
75 int ids;
76 int (*show)(struct seq_file *, void *);
77};
78
79/**
80 * ipc_init - initialise ipc subsystem
81 *
82 * The various sysv ipc resources (semaphores, messages and shared
83 * memory) are initialised.
84 *
85 * A callback routine is registered into the memory hotplug notifier
86 * chain: since msgmni scales to lowmem this callback routine will be
87 * called upon successful memory add / remove to recompute msmgni.
88 */
89static int __init ipc_init(void)
90{
91 proc_mkdir("sysvipc", NULL);
92 sem_init();
93 msg_init();
94 shm_init();
95
96 return 0;
97}
98device_initcall(ipc_init);
99
100static const struct rhashtable_params ipc_kht_params = {
101 .head_offset = offsetof(struct kern_ipc_perm, khtnode),
102 .key_offset = offsetof(struct kern_ipc_perm, key),
103 .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key),
104 .automatic_shrinking = true,
105};
106
107/**
108 * ipc_init_ids - initialise ipc identifiers
109 * @ids: ipc identifier set
110 *
111 * Set up the sequence range to use for the ipc identifier range (limited
112 * below ipc_mni) then initialise the keys hashtable and ids idr.
113 */
114void ipc_init_ids(struct ipc_ids *ids)
115{
116 ids->in_use = 0;
117 ids->seq = 0;
118 init_rwsem(&ids->rwsem);
119 rhashtable_init(&ids->key_ht, &ipc_kht_params);
120 idr_init(&ids->ipcs_idr);
121 ids->max_idx = -1;
122 ids->last_idx = -1;
123#ifdef CONFIG_CHECKPOINT_RESTORE
124 ids->next_id = -1;
125#endif
126}
127
128#ifdef CONFIG_PROC_FS
129static const struct file_operations sysvipc_proc_fops;
130/**
131 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
132 * @path: Path in procfs
133 * @header: Banner to be printed at the beginning of the file.
134 * @ids: ipc id table to iterate.
135 * @show: show routine.
136 */
137void __init ipc_init_proc_interface(const char *path, const char *header,
138 int ids, int (*show)(struct seq_file *, void *))
139{
140 struct proc_dir_entry *pde;
141 struct ipc_proc_iface *iface;
142
143 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
144 if (!iface)
145 return;
146 iface->path = path;
147 iface->header = header;
148 iface->ids = ids;
149 iface->show = show;
150
151 pde = proc_create_data(path,
152 S_IRUGO, /* world readable */
153 NULL, /* parent dir */
154 &sysvipc_proc_fops,
155 iface);
156 if (!pde)
157 kfree(iface);
158}
159#endif
160
161/**
162 * ipc_findkey - find a key in an ipc identifier set
163 * @ids: ipc identifier set
164 * @key: key to find
165 *
166 * Returns the locked pointer to the ipc structure if found or NULL
167 * otherwise. If key is found ipc points to the owning ipc structure
168 *
169 * Called with writer ipc_ids.rwsem held.
170 */
171static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
172{
173 struct kern_ipc_perm *ipcp;
174
175 ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
176 ipc_kht_params);
177 if (!ipcp)
178 return NULL;
179
180 rcu_read_lock();
181 ipc_lock_object(ipcp);
182 return ipcp;
183}
184
185/*
186 * Insert new IPC object into idr tree, and set sequence number and id
187 * in the correct order.
188 * Especially:
189 * - the sequence number must be set before inserting the object into the idr,
190 * because the sequence number is accessed without a lock.
191 * - the id can/must be set after inserting the object into the idr.
192 * All accesses must be done after getting kern_ipc_perm.lock.
193 *
194 * The caller must own kern_ipc_perm.lock.of the new object.
195 * On error, the function returns a (negative) error code.
196 *
197 * To conserve sequence number space, especially with extended ipc_mni,
198 * the sequence number is incremented only when the returned ID is less than
199 * the last one.
200 */
201static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
202{
203 int idx, next_id = -1;
204
205#ifdef CONFIG_CHECKPOINT_RESTORE
206 next_id = ids->next_id;
207 ids->next_id = -1;
208#endif
209
210 /*
211 * As soon as a new object is inserted into the idr,
212 * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
213 * and the lockless preparations for ipc operations can start.
214 * This means especially: permission checks, audit calls, allocation
215 * of undo structures, ...
216 *
217 * Thus the object must be fully initialized, and if something fails,
218 * then the full tear-down sequence must be followed.
219 * (i.e.: set new->deleted, reduce refcount, call_rcu())
220 */
221
222 if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
223 int max_idx;
224
225 max_idx = max(ids->in_use*3/2, ipc_min_cycle);
226 max_idx = min(max_idx, ipc_mni);
227
228 /* allocate the idx, with a NULL struct kern_ipc_perm */
229 idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
230 GFP_NOWAIT);
231
232 if (idx >= 0) {
233 /*
234 * idx got allocated successfully.
235 * Now calculate the sequence number and set the
236 * pointer for real.
237 */
238 if (idx <= ids->last_idx) {
239 ids->seq++;
240 if (ids->seq >= ipcid_seq_max())
241 ids->seq = 0;
242 }
243 ids->last_idx = idx;
244
245 new->seq = ids->seq;
246 /* no need for smp_wmb(), this is done
247 * inside idr_replace, as part of
248 * rcu_assign_pointer
249 */
250 idr_replace(&ids->ipcs_idr, new, idx);
251 }
252 } else {
253 new->seq = ipcid_to_seqx(next_id);
254 idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
255 0, GFP_NOWAIT);
256 }
257 if (idx >= 0)
258 new->id = (new->seq << ipcmni_seq_shift()) + idx;
259 return idx;
260}
261
262/**
263 * ipc_addid - add an ipc identifier
264 * @ids: ipc identifier set
265 * @new: new ipc permission set
266 * @limit: limit for the number of used ids
267 *
268 * Add an entry 'new' to the ipc ids idr. The permissions object is
269 * initialised and the first free entry is set up and the index assigned
270 * is returned. The 'new' entry is returned in a locked state on success.
271 *
272 * On failure the entry is not locked and a negative err-code is returned.
273 * The caller must use ipc_rcu_putref() to free the identifier.
274 *
275 * Called with writer ipc_ids.rwsem held.
276 */
277int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
278{
279 kuid_t euid;
280 kgid_t egid;
281 int idx, err;
282
283 /* 1) Initialize the refcount so that ipc_rcu_putref works */
284 refcount_set(&new->refcount, 1);
285
286 if (limit > ipc_mni)
287 limit = ipc_mni;
288
289 if (ids->in_use >= limit)
290 return -ENOSPC;
291
292 idr_preload(GFP_KERNEL);
293
294 spin_lock_init(&new->lock);
295 rcu_read_lock();
296 spin_lock(&new->lock);
297
298 current_euid_egid(&euid, &egid);
299 new->cuid = new->uid = euid;
300 new->gid = new->cgid = egid;
301
302 new->deleted = false;
303
304 idx = ipc_idr_alloc(ids, new);
305 idr_preload_end();
306
307 if (idx >= 0 && new->key != IPC_PRIVATE) {
308 err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
309 ipc_kht_params);
310 if (err < 0) {
311 idr_remove(&ids->ipcs_idr, idx);
312 idx = err;
313 }
314 }
315 if (idx < 0) {
316 new->deleted = true;
317 spin_unlock(&new->lock);
318 rcu_read_unlock();
319 return idx;
320 }
321
322 ids->in_use++;
323 if (idx > ids->max_idx)
324 ids->max_idx = idx;
325 return idx;
326}
327
328/**
329 * ipcget_new - create a new ipc object
330 * @ns: ipc namespace
331 * @ids: ipc identifier set
332 * @ops: the actual creation routine to call
333 * @params: its parameters
334 *
335 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
336 * when the key is IPC_PRIVATE.
337 */
338static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
339 const struct ipc_ops *ops, struct ipc_params *params)
340{
341 int err;
342
343 down_write(&ids->rwsem);
344 err = ops->getnew(ns, params);
345 up_write(&ids->rwsem);
346 return err;
347}
348
349/**
350 * ipc_check_perms - check security and permissions for an ipc object
351 * @ns: ipc namespace
352 * @ipcp: ipc permission set
353 * @ops: the actual security routine to call
354 * @params: its parameters
355 *
356 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
357 * when the key is not IPC_PRIVATE and that key already exists in the
358 * ds IDR.
359 *
360 * On success, the ipc id is returned.
361 *
362 * It is called with ipc_ids.rwsem and ipcp->lock held.
363 */
364static int ipc_check_perms(struct ipc_namespace *ns,
365 struct kern_ipc_perm *ipcp,
366 const struct ipc_ops *ops,
367 struct ipc_params *params)
368{
369 int err;
370
371 if (ipcperms(ns, ipcp, params->flg))
372 err = -EACCES;
373 else {
374 err = ops->associate(ipcp, params->flg);
375 if (!err)
376 err = ipcp->id;
377 }
378
379 return err;
380}
381
382/**
383 * ipcget_public - get an ipc object or create a new one
384 * @ns: ipc namespace
385 * @ids: ipc identifier set
386 * @ops: the actual creation routine to call
387 * @params: its parameters
388 *
389 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
390 * when the key is not IPC_PRIVATE.
391 * It adds a new entry if the key is not found and does some permission
392 * / security checkings if the key is found.
393 *
394 * On success, the ipc id is returned.
395 */
396static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
397 const struct ipc_ops *ops, struct ipc_params *params)
398{
399 struct kern_ipc_perm *ipcp;
400 int flg = params->flg;
401 int err;
402
403 /*
404 * Take the lock as a writer since we are potentially going to add
405 * a new entry + read locks are not "upgradable"
406 */
407 down_write(&ids->rwsem);
408 ipcp = ipc_findkey(ids, params->key);
409 if (ipcp == NULL) {
410 /* key not used */
411 if (!(flg & IPC_CREAT))
412 err = -ENOENT;
413 else
414 err = ops->getnew(ns, params);
415 } else {
416 /* ipc object has been locked by ipc_findkey() */
417
418 if (flg & IPC_CREAT && flg & IPC_EXCL)
419 err = -EEXIST;
420 else {
421 err = 0;
422 if (ops->more_checks)
423 err = ops->more_checks(ipcp, params);
424 if (!err)
425 /*
426 * ipc_check_perms returns the IPC id on
427 * success
428 */
429 err = ipc_check_perms(ns, ipcp, ops, params);
430 }
431 ipc_unlock(ipcp);
432 }
433 up_write(&ids->rwsem);
434
435 return err;
436}
437
438/**
439 * ipc_kht_remove - remove an ipc from the key hashtable
440 * @ids: ipc identifier set
441 * @ipcp: ipc perm structure containing the key to remove
442 *
443 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
444 * before this function is called, and remain locked on the exit.
445 */
446static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
447{
448 if (ipcp->key != IPC_PRIVATE)
449 rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
450 ipc_kht_params);
451}
452
453/**
454 * ipc_rmid - remove an ipc identifier
455 * @ids: ipc identifier set
456 * @ipcp: ipc perm structure containing the identifier to remove
457 *
458 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
459 * before this function is called, and remain locked on the exit.
460 */
461void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
462{
463 int idx = ipcid_to_idx(ipcp->id);
464
465 idr_remove(&ids->ipcs_idr, idx);
466 ipc_kht_remove(ids, ipcp);
467 ids->in_use--;
468 ipcp->deleted = true;
469
470 if (unlikely(idx == ids->max_idx)) {
471 do {
472 idx--;
473 if (idx == -1)
474 break;
475 } while (!idr_find(&ids->ipcs_idr, idx));
476 ids->max_idx = idx;
477 }
478}
479
480/**
481 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
482 * @ids: ipc identifier set
483 * @ipcp: ipc perm structure containing the key to modify
484 *
485 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
486 * before this function is called, and remain locked on the exit.
487 */
488void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
489{
490 ipc_kht_remove(ids, ipcp);
491 ipcp->key = IPC_PRIVATE;
492}
493
494bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
495{
496 return refcount_inc_not_zero(&ptr->refcount);
497}
498
499void ipc_rcu_putref(struct kern_ipc_perm *ptr,
500 void (*func)(struct rcu_head *head))
501{
502 if (!refcount_dec_and_test(&ptr->refcount))
503 return;
504
505 call_rcu(&ptr->rcu, func);
506}
507
508/**
509 * ipcperms - check ipc permissions
510 * @ns: ipc namespace
511 * @ipcp: ipc permission set
512 * @flag: desired permission set
513 *
514 * Check user, group, other permissions for access
515 * to ipc resources. return 0 if allowed
516 *
517 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
518 */
519int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
520{
521 kuid_t euid = current_euid();
522 int requested_mode, granted_mode;
523
524 audit_ipc_obj(ipcp);
525 requested_mode = (flag >> 6) | (flag >> 3) | flag;
526 granted_mode = ipcp->mode;
527 if (uid_eq(euid, ipcp->cuid) ||
528 uid_eq(euid, ipcp->uid))
529 granted_mode >>= 6;
530 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
531 granted_mode >>= 3;
532 /* is there some bit set in requested_mode but not in granted_mode? */
533 if ((requested_mode & ~granted_mode & 0007) &&
534 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
535 return -1;
536
537 return security_ipc_permission(ipcp, flag);
538}
539
540/*
541 * Functions to convert between the kern_ipc_perm structure and the
542 * old/new ipc_perm structures
543 */
544
545/**
546 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
547 * @in: kernel permissions
548 * @out: new style ipc permissions
549 *
550 * Turn the kernel object @in into a set of permissions descriptions
551 * for returning to userspace (@out).
552 */
553void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
554{
555 out->key = in->key;
556 out->uid = from_kuid_munged(current_user_ns(), in->uid);
557 out->gid = from_kgid_munged(current_user_ns(), in->gid);
558 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
559 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
560 out->mode = in->mode;
561 out->seq = in->seq;
562}
563
564/**
565 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
566 * @in: new style ipc permissions
567 * @out: old style ipc permissions
568 *
569 * Turn the new style permissions object @in into a compatibility
570 * object and store it into the @out pointer.
571 */
572void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
573{
574 out->key = in->key;
575 SET_UID(out->uid, in->uid);
576 SET_GID(out->gid, in->gid);
577 SET_UID(out->cuid, in->cuid);
578 SET_GID(out->cgid, in->cgid);
579 out->mode = in->mode;
580 out->seq = in->seq;
581}
582
583/**
584 * ipc_obtain_object_idr
585 * @ids: ipc identifier set
586 * @id: ipc id to look for
587 *
588 * Look for an id in the ipc ids idr and return associated ipc object.
589 *
590 * Call inside the RCU critical section.
591 * The ipc object is *not* locked on exit.
592 */
593struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
594{
595 struct kern_ipc_perm *out;
596 int idx = ipcid_to_idx(id);
597
598 out = idr_find(&ids->ipcs_idr, idx);
599 if (!out)
600 return ERR_PTR(-EINVAL);
601
602 return out;
603}
604
605/**
606 * ipc_obtain_object_check
607 * @ids: ipc identifier set
608 * @id: ipc id to look for
609 *
610 * Similar to ipc_obtain_object_idr() but also checks the ipc object
611 * sequence number.
612 *
613 * Call inside the RCU critical section.
614 * The ipc object is *not* locked on exit.
615 */
616struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
617{
618 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
619
620 if (IS_ERR(out))
621 goto out;
622
623 if (ipc_checkid(out, id))
624 return ERR_PTR(-EINVAL);
625out:
626 return out;
627}
628
629/**
630 * ipcget - Common sys_*get() code
631 * @ns: namespace
632 * @ids: ipc identifier set
633 * @ops: operations to be called on ipc object creation, permission checks
634 * and further checks
635 * @params: the parameters needed by the previous operations.
636 *
637 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
638 */
639int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
640 const struct ipc_ops *ops, struct ipc_params *params)
641{
642 if (params->key == IPC_PRIVATE)
643 return ipcget_new(ns, ids, ops, params);
644 else
645 return ipcget_public(ns, ids, ops, params);
646}
647
648/**
649 * ipc_update_perm - update the permissions of an ipc object
650 * @in: the permission given as input.
651 * @out: the permission of the ipc to set.
652 */
653int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
654{
655 kuid_t uid = make_kuid(current_user_ns(), in->uid);
656 kgid_t gid = make_kgid(current_user_ns(), in->gid);
657 if (!uid_valid(uid) || !gid_valid(gid))
658 return -EINVAL;
659
660 out->uid = uid;
661 out->gid = gid;
662 out->mode = (out->mode & ~S_IRWXUGO)
663 | (in->mode & S_IRWXUGO);
664
665 return 0;
666}
667
668/**
669 * ipcctl_obtain_check - retrieve an ipc object and check permissions
670 * @ns: ipc namespace
671 * @ids: the table of ids where to look for the ipc
672 * @id: the id of the ipc to retrieve
673 * @cmd: the cmd to check
674 * @perm: the permission to set
675 * @extra_perm: one extra permission parameter used by msq
676 *
677 * This function does some common audit and permissions check for some IPC_XXX
678 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
679 *
680 * It:
681 * - retrieves the ipc object with the given id in the given table.
682 * - performs some audit and permission check, depending on the given cmd
683 * - returns a pointer to the ipc object or otherwise, the corresponding
684 * error.
685 *
686 * Call holding the both the rwsem and the rcu read lock.
687 */
688struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
689 struct ipc_ids *ids, int id, int cmd,
690 struct ipc64_perm *perm, int extra_perm)
691{
692 kuid_t euid;
693 int err = -EPERM;
694 struct kern_ipc_perm *ipcp;
695
696 ipcp = ipc_obtain_object_check(ids, id);
697 if (IS_ERR(ipcp)) {
698 err = PTR_ERR(ipcp);
699 goto err;
700 }
701
702 audit_ipc_obj(ipcp);
703 if (cmd == IPC_SET)
704 audit_ipc_set_perm(extra_perm, perm->uid,
705 perm->gid, perm->mode);
706
707 euid = current_euid();
708 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
709 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
710 return ipcp; /* successful lookup */
711err:
712 return ERR_PTR(err);
713}
714
715#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
716
717
718/**
719 * ipc_parse_version - ipc call version
720 * @cmd: pointer to command
721 *
722 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
723 * The @cmd value is turned from an encoding command and version into
724 * just the command code.
725 */
726int ipc_parse_version(int *cmd)
727{
728 if (*cmd & IPC_64) {
729 *cmd ^= IPC_64;
730 return IPC_64;
731 } else {
732 return IPC_OLD;
733 }
734}
735
736#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
737
738#ifdef CONFIG_PROC_FS
739struct ipc_proc_iter {
740 struct ipc_namespace *ns;
741 struct pid_namespace *pid_ns;
742 struct ipc_proc_iface *iface;
743};
744
745struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
746{
747 struct ipc_proc_iter *iter = s->private;
748 return iter->pid_ns;
749}
750
751/*
752 * This routine locks the ipc structure found at least at position pos.
753 */
754static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
755 loff_t *new_pos)
756{
757 struct kern_ipc_perm *ipc;
758 int total, id;
759
760 total = 0;
761 for (id = 0; id < pos && total < ids->in_use; id++) {
762 ipc = idr_find(&ids->ipcs_idr, id);
763 if (ipc != NULL)
764 total++;
765 }
766
767 if (total >= ids->in_use)
768 return NULL;
769
770 for (; pos < ipc_mni; pos++) {
771 ipc = idr_find(&ids->ipcs_idr, pos);
772 if (ipc != NULL) {
773 *new_pos = pos + 1;
774 rcu_read_lock();
775 ipc_lock_object(ipc);
776 return ipc;
777 }
778 }
779
780 /* Out of range - return NULL to terminate iteration */
781 return NULL;
782}
783
784static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
785{
786 struct ipc_proc_iter *iter = s->private;
787 struct ipc_proc_iface *iface = iter->iface;
788 struct kern_ipc_perm *ipc = it;
789
790 /* If we had an ipc id locked before, unlock it */
791 if (ipc && ipc != SEQ_START_TOKEN)
792 ipc_unlock(ipc);
793
794 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
795}
796
797/*
798 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
799 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
800 */
801static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
802{
803 struct ipc_proc_iter *iter = s->private;
804 struct ipc_proc_iface *iface = iter->iface;
805 struct ipc_ids *ids;
806
807 ids = &iter->ns->ids[iface->ids];
808
809 /*
810 * Take the lock - this will be released by the corresponding
811 * call to stop().
812 */
813 down_read(&ids->rwsem);
814
815 /* pos < 0 is invalid */
816 if (*pos < 0)
817 return NULL;
818
819 /* pos == 0 means header */
820 if (*pos == 0)
821 return SEQ_START_TOKEN;
822
823 /* Find the (pos-1)th ipc */
824 return sysvipc_find_ipc(ids, *pos - 1, pos);
825}
826
827static void sysvipc_proc_stop(struct seq_file *s, void *it)
828{
829 struct kern_ipc_perm *ipc = it;
830 struct ipc_proc_iter *iter = s->private;
831 struct ipc_proc_iface *iface = iter->iface;
832 struct ipc_ids *ids;
833
834 /* If we had a locked structure, release it */
835 if (ipc && ipc != SEQ_START_TOKEN)
836 ipc_unlock(ipc);
837
838 ids = &iter->ns->ids[iface->ids];
839 /* Release the lock we took in start() */
840 up_read(&ids->rwsem);
841}
842
843static int sysvipc_proc_show(struct seq_file *s, void *it)
844{
845 struct ipc_proc_iter *iter = s->private;
846 struct ipc_proc_iface *iface = iter->iface;
847
848 if (it == SEQ_START_TOKEN) {
849 seq_puts(s, iface->header);
850 return 0;
851 }
852
853 return iface->show(s, it);
854}
855
856static const struct seq_operations sysvipc_proc_seqops = {
857 .start = sysvipc_proc_start,
858 .stop = sysvipc_proc_stop,
859 .next = sysvipc_proc_next,
860 .show = sysvipc_proc_show,
861};
862
863static int sysvipc_proc_open(struct inode *inode, struct file *file)
864{
865 struct ipc_proc_iter *iter;
866
867 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
868 if (!iter)
869 return -ENOMEM;
870
871 iter->iface = PDE_DATA(inode);
872 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
873 iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
874
875 return 0;
876}
877
878static int sysvipc_proc_release(struct inode *inode, struct file *file)
879{
880 struct seq_file *seq = file->private_data;
881 struct ipc_proc_iter *iter = seq->private;
882 put_ipc_ns(iter->ns);
883 put_pid_ns(iter->pid_ns);
884 return seq_release_private(inode, file);
885}
886
887static const struct file_operations sysvipc_proc_fops = {
888 .open = sysvipc_proc_open,
889 .read = seq_read,
890 .llseek = seq_lseek,
891 .release = sysvipc_proc_release,
892};
893#endif /* CONFIG_PROC_FS */
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 * General sysv ipc locking scheme:
20 * rcu_read_lock()
21 * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
22 * tree.
23 * - perform initial checks (capabilities, auditing and permission,
24 * etc).
25 * - perform read-only operations, such as STAT, INFO commands.
26 * acquire the ipc lock (kern_ipc_perm.lock) through
27 * ipc_lock_object()
28 * - perform data updates, such as SET, RMID commands and
29 * mechanism-specific operations (semop/semtimedop,
30 * msgsnd/msgrcv, shmat/shmdt).
31 * drop the ipc lock, through ipc_unlock_object().
32 * rcu_read_unlock()
33 *
34 * The ids->rwsem must be taken when:
35 * - creating, removing and iterating the existing entries in ipc
36 * identifier sets.
37 * - iterating through files under /proc/sysvipc/
38 *
39 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
40 * see sem_lock().
41 */
42
43#include <linux/mm.h>
44#include <linux/shm.h>
45#include <linux/init.h>
46#include <linux/msg.h>
47#include <linux/vmalloc.h>
48#include <linux/slab.h>
49#include <linux/notifier.h>
50#include <linux/capability.h>
51#include <linux/highuid.h>
52#include <linux/security.h>
53#include <linux/rcupdate.h>
54#include <linux/workqueue.h>
55#include <linux/seq_file.h>
56#include <linux/proc_fs.h>
57#include <linux/audit.h>
58#include <linux/nsproxy.h>
59#include <linux/rwsem.h>
60#include <linux/memory.h>
61#include <linux/ipc_namespace.h>
62
63#include <asm/unistd.h>
64
65#include "util.h"
66
67struct ipc_proc_iface {
68 const char *path;
69 const char *header;
70 int ids;
71 int (*show)(struct seq_file *, void *);
72};
73
74static void ipc_memory_notifier(struct work_struct *work)
75{
76 ipcns_notify(IPCNS_MEMCHANGED);
77}
78
79static int ipc_memory_callback(struct notifier_block *self,
80 unsigned long action, void *arg)
81{
82 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
83
84 switch (action) {
85 case MEM_ONLINE: /* memory successfully brought online */
86 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
87 /*
88 * This is done by invoking the ipcns notifier chain with the
89 * IPC_MEMCHANGED event.
90 * In order not to keep the lock on the hotplug memory chain
91 * for too long, queue a work item that will, when waken up,
92 * activate the ipcns notification chain.
93 */
94 schedule_work(&ipc_memory_wq);
95 break;
96 case MEM_GOING_ONLINE:
97 case MEM_GOING_OFFLINE:
98 case MEM_CANCEL_ONLINE:
99 case MEM_CANCEL_OFFLINE:
100 default:
101 break;
102 }
103
104 return NOTIFY_OK;
105}
106
107static struct notifier_block ipc_memory_nb = {
108 .notifier_call = ipc_memory_callback,
109 .priority = IPC_CALLBACK_PRI,
110};
111
112/**
113 * ipc_init - initialise ipc subsystem
114 *
115 * The various sysv ipc resources (semaphores, messages and shared
116 * memory) are initialised.
117 *
118 * A callback routine is registered into the memory hotplug notifier
119 * chain: since msgmni scales to lowmem this callback routine will be
120 * called upon successful memory add / remove to recompute msmgni.
121 */
122static int __init ipc_init(void)
123{
124 sem_init();
125 msg_init();
126 shm_init();
127 register_hotmemory_notifier(&ipc_memory_nb);
128 register_ipcns_notifier(&init_ipc_ns);
129 return 0;
130}
131device_initcall(ipc_init);
132
133/**
134 * ipc_init_ids - initialise ipc identifiers
135 * @ids: ipc identifier set
136 *
137 * Set up the sequence range to use for the ipc identifier range (limited
138 * below IPCMNI) then initialise the ids idr.
139 */
140void ipc_init_ids(struct ipc_ids *ids)
141{
142 ids->in_use = 0;
143 ids->seq = 0;
144 ids->next_id = -1;
145 init_rwsem(&ids->rwsem);
146 idr_init(&ids->ipcs_idr);
147}
148
149#ifdef CONFIG_PROC_FS
150static const struct file_operations sysvipc_proc_fops;
151/**
152 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
153 * @path: Path in procfs
154 * @header: Banner to be printed at the beginning of the file.
155 * @ids: ipc id table to iterate.
156 * @show: show routine.
157 */
158void __init ipc_init_proc_interface(const char *path, const char *header,
159 int ids, int (*show)(struct seq_file *, void *))
160{
161 struct proc_dir_entry *pde;
162 struct ipc_proc_iface *iface;
163
164 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
165 if (!iface)
166 return;
167 iface->path = path;
168 iface->header = header;
169 iface->ids = ids;
170 iface->show = show;
171
172 pde = proc_create_data(path,
173 S_IRUGO, /* world readable */
174 NULL, /* parent dir */
175 &sysvipc_proc_fops,
176 iface);
177 if (!pde)
178 kfree(iface);
179}
180#endif
181
182/**
183 * ipc_findkey - find a key in an ipc identifier set
184 * @ids: ipc identifier set
185 * @key: key to find
186 *
187 * Returns the locked pointer to the ipc structure if found or NULL
188 * otherwise. If key is found ipc points to the owning ipc structure
189 *
190 * Called with ipc_ids.rwsem held.
191 */
192static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
193{
194 struct kern_ipc_perm *ipc;
195 int next_id;
196 int total;
197
198 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
199 ipc = idr_find(&ids->ipcs_idr, next_id);
200
201 if (ipc == NULL)
202 continue;
203
204 if (ipc->key != key) {
205 total++;
206 continue;
207 }
208
209 rcu_read_lock();
210 ipc_lock_object(ipc);
211 return ipc;
212 }
213
214 return NULL;
215}
216
217/**
218 * ipc_get_maxid - get the last assigned id
219 * @ids: ipc identifier set
220 *
221 * Called with ipc_ids.rwsem held.
222 */
223int ipc_get_maxid(struct ipc_ids *ids)
224{
225 struct kern_ipc_perm *ipc;
226 int max_id = -1;
227 int total, id;
228
229 if (ids->in_use == 0)
230 return -1;
231
232 if (ids->in_use == IPCMNI)
233 return IPCMNI - 1;
234
235 /* Look for the last assigned id */
236 total = 0;
237 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
238 ipc = idr_find(&ids->ipcs_idr, id);
239 if (ipc != NULL) {
240 max_id = id;
241 total++;
242 }
243 }
244 return max_id;
245}
246
247/**
248 * ipc_addid - add an ipc identifier
249 * @ids: ipc identifier set
250 * @new: new ipc permission set
251 * @size: limit for the number of used ids
252 *
253 * Add an entry 'new' to the ipc ids idr. The permissions object is
254 * initialised and the first free entry is set up and the id assigned
255 * is returned. The 'new' entry is returned in a locked state on success.
256 * On failure the entry is not locked and a negative err-code is returned.
257 *
258 * Called with writer ipc_ids.rwsem held.
259 */
260int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
261{
262 kuid_t euid;
263 kgid_t egid;
264 int id;
265 int next_id = ids->next_id;
266
267 if (size > IPCMNI)
268 size = IPCMNI;
269
270 if (ids->in_use >= size)
271 return -ENOSPC;
272
273 idr_preload(GFP_KERNEL);
274
275 spin_lock_init(&new->lock);
276 new->deleted = false;
277 rcu_read_lock();
278 spin_lock(&new->lock);
279
280 id = idr_alloc(&ids->ipcs_idr, new,
281 (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
282 GFP_NOWAIT);
283 idr_preload_end();
284 if (id < 0) {
285 spin_unlock(&new->lock);
286 rcu_read_unlock();
287 return id;
288 }
289
290 ids->in_use++;
291
292 current_euid_egid(&euid, &egid);
293 new->cuid = new->uid = euid;
294 new->gid = new->cgid = egid;
295
296 if (next_id < 0) {
297 new->seq = ids->seq++;
298 if (ids->seq > IPCID_SEQ_MAX)
299 ids->seq = 0;
300 } else {
301 new->seq = ipcid_to_seqx(next_id);
302 ids->next_id = -1;
303 }
304
305 new->id = ipc_buildid(id, new->seq);
306 return id;
307}
308
309/**
310 * ipcget_new - create a new ipc object
311 * @ns: ipc namespace
312 * @ids: ipc identifer set
313 * @ops: the actual creation routine to call
314 * @params: its parameters
315 *
316 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
317 * when the key is IPC_PRIVATE.
318 */
319static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
320 struct ipc_ops *ops, struct ipc_params *params)
321{
322 int err;
323
324 down_write(&ids->rwsem);
325 err = ops->getnew(ns, params);
326 up_write(&ids->rwsem);
327 return err;
328}
329
330/**
331 * ipc_check_perms - check security and permissions for an ipc object
332 * @ns: ipc namespace
333 * @ipcp: ipc permission set
334 * @ops: the actual security routine to call
335 * @params: its parameters
336 *
337 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
338 * when the key is not IPC_PRIVATE and that key already exists in the
339 * ds IDR.
340 *
341 * On success, the ipc id is returned.
342 *
343 * It is called with ipc_ids.rwsem and ipcp->lock held.
344 */
345static int ipc_check_perms(struct ipc_namespace *ns,
346 struct kern_ipc_perm *ipcp,
347 struct ipc_ops *ops,
348 struct ipc_params *params)
349{
350 int err;
351
352 if (ipcperms(ns, ipcp, params->flg))
353 err = -EACCES;
354 else {
355 err = ops->associate(ipcp, params->flg);
356 if (!err)
357 err = ipcp->id;
358 }
359
360 return err;
361}
362
363/**
364 * ipcget_public - get an ipc object or create a new one
365 * @ns: ipc namespace
366 * @ids: ipc identifer set
367 * @ops: the actual creation routine to call
368 * @params: its parameters
369 *
370 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
371 * when the key is not IPC_PRIVATE.
372 * It adds a new entry if the key is not found and does some permission
373 * / security checkings if the key is found.
374 *
375 * On success, the ipc id is returned.
376 */
377static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
378 struct ipc_ops *ops, struct ipc_params *params)
379{
380 struct kern_ipc_perm *ipcp;
381 int flg = params->flg;
382 int err;
383
384 /*
385 * Take the lock as a writer since we are potentially going to add
386 * a new entry + read locks are not "upgradable"
387 */
388 down_write(&ids->rwsem);
389 ipcp = ipc_findkey(ids, params->key);
390 if (ipcp == NULL) {
391 /* key not used */
392 if (!(flg & IPC_CREAT))
393 err = -ENOENT;
394 else
395 err = ops->getnew(ns, params);
396 } else {
397 /* ipc object has been locked by ipc_findkey() */
398
399 if (flg & IPC_CREAT && flg & IPC_EXCL)
400 err = -EEXIST;
401 else {
402 err = 0;
403 if (ops->more_checks)
404 err = ops->more_checks(ipcp, params);
405 if (!err)
406 /*
407 * ipc_check_perms returns the IPC id on
408 * success
409 */
410 err = ipc_check_perms(ns, ipcp, ops, params);
411 }
412 ipc_unlock(ipcp);
413 }
414 up_write(&ids->rwsem);
415
416 return err;
417}
418
419
420/**
421 * ipc_rmid - remove an ipc identifier
422 * @ids: ipc identifier set
423 * @ipcp: ipc perm structure containing the identifier to remove
424 *
425 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
426 * before this function is called, and remain locked on the exit.
427 */
428void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
429{
430 int lid = ipcid_to_idx(ipcp->id);
431
432 idr_remove(&ids->ipcs_idr, lid);
433 ids->in_use--;
434 ipcp->deleted = true;
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 */
444void *ipc_alloc(int size)
445{
446 void *out;
447 if (size > PAGE_SIZE)
448 out = vmalloc(size);
449 else
450 out = kmalloc(size, GFP_KERNEL);
451 return out;
452}
453
454/**
455 * ipc_free - free ipc space
456 * @ptr: pointer returned by ipc_alloc
457 * @size: size of block
458 *
459 * Free a block created with ipc_alloc(). The caller must know the size
460 * used in the allocation call.
461 */
462void ipc_free(void *ptr, int size)
463{
464 if (size > PAGE_SIZE)
465 vfree(ptr);
466 else
467 kfree(ptr);
468}
469
470/**
471 * ipc_rcu_alloc - allocate ipc and rcu space
472 * @size: size desired
473 *
474 * Allocate memory for the rcu header structure + the object.
475 * Returns the pointer to the object or NULL upon failure.
476 */
477void *ipc_rcu_alloc(int size)
478{
479 /*
480 * We prepend the allocation with the rcu struct
481 */
482 struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
483 if (unlikely(!out))
484 return NULL;
485 atomic_set(&out->refcount, 1);
486 return out + 1;
487}
488
489int ipc_rcu_getref(void *ptr)
490{
491 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
492
493 return atomic_inc_not_zero(&p->refcount);
494}
495
496void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
497{
498 struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
499
500 if (!atomic_dec_and_test(&p->refcount))
501 return;
502
503 call_rcu(&p->rcu, func);
504}
505
506void ipc_rcu_free(struct rcu_head *head)
507{
508 struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
509
510 if (is_vmalloc_addr(p))
511 vfree(p);
512 else
513 kfree(p);
514}
515
516/**
517 * ipcperms - check ipc permissions
518 * @ns: ipc namespace
519 * @ipcp: ipc permission set
520 * @flag: desired permission set
521 *
522 * Check user, group, other permissions for access
523 * to ipc resources. return 0 if allowed
524 *
525 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
526 */
527int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
528{
529 kuid_t euid = current_euid();
530 int requested_mode, granted_mode;
531
532 audit_ipc_obj(ipcp);
533 requested_mode = (flag >> 6) | (flag >> 3) | flag;
534 granted_mode = ipcp->mode;
535 if (uid_eq(euid, ipcp->cuid) ||
536 uid_eq(euid, ipcp->uid))
537 granted_mode >>= 6;
538 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
539 granted_mode >>= 3;
540 /* is there some bit set in requested_mode but not in granted_mode? */
541 if ((requested_mode & ~granted_mode & 0007) &&
542 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
543 return -1;
544
545 return security_ipc_permission(ipcp, flag);
546}
547
548/*
549 * Functions to convert between the kern_ipc_perm structure and the
550 * old/new ipc_perm structures
551 */
552
553/**
554 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
555 * @in: kernel permissions
556 * @out: new style ipc permissions
557 *
558 * Turn the kernel object @in into a set of permissions descriptions
559 * for returning to userspace (@out).
560 */
561void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
562{
563 out->key = in->key;
564 out->uid = from_kuid_munged(current_user_ns(), in->uid);
565 out->gid = from_kgid_munged(current_user_ns(), in->gid);
566 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
567 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
568 out->mode = in->mode;
569 out->seq = in->seq;
570}
571
572/**
573 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
574 * @in: new style ipc permissions
575 * @out: old style ipc permissions
576 *
577 * Turn the new style permissions object @in into a compatibility
578 * object and store it into the @out pointer.
579 */
580void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
581{
582 out->key = in->key;
583 SET_UID(out->uid, in->uid);
584 SET_GID(out->gid, in->gid);
585 SET_UID(out->cuid, in->cuid);
586 SET_GID(out->cgid, in->cgid);
587 out->mode = in->mode;
588 out->seq = in->seq;
589}
590
591/**
592 * ipc_obtain_object
593 * @ids: ipc identifier set
594 * @id: ipc id to look for
595 *
596 * Look for an id in the ipc ids idr and return associated ipc object.
597 *
598 * Call inside the RCU critical section.
599 * The ipc object is *not* locked on exit.
600 */
601struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
602{
603 struct kern_ipc_perm *out;
604 int lid = ipcid_to_idx(id);
605
606 out = idr_find(&ids->ipcs_idr, lid);
607 if (!out)
608 return ERR_PTR(-EINVAL);
609
610 return out;
611}
612
613/**
614 * ipc_lock - lock an ipc structure without rwsem held
615 * @ids: ipc identifier set
616 * @id: ipc id to look for
617 *
618 * Look for an id in the ipc ids idr and lock the associated ipc object.
619 *
620 * The ipc object is locked on successful exit.
621 */
622struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
623{
624 struct kern_ipc_perm *out;
625
626 rcu_read_lock();
627 out = ipc_obtain_object(ids, id);
628 if (IS_ERR(out))
629 goto err1;
630
631 spin_lock(&out->lock);
632
633 /* ipc_rmid() may have already freed the ID while ipc_lock
634 * was spinning: here verify that the structure is still valid
635 */
636 if (ipc_valid_object(out))
637 return out;
638
639 spin_unlock(&out->lock);
640 out = ERR_PTR(-EINVAL);
641err1:
642 rcu_read_unlock();
643 return out;
644}
645
646/**
647 * ipc_obtain_object_check
648 * @ids: ipc identifier set
649 * @id: ipc id to look for
650 *
651 * Similar to ipc_obtain_object() but also checks
652 * the ipc object reference counter.
653 *
654 * Call inside the RCU critical section.
655 * The ipc object is *not* locked on exit.
656 */
657struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
658{
659 struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
660
661 if (IS_ERR(out))
662 goto out;
663
664 if (ipc_checkid(out, id))
665 return ERR_PTR(-EIDRM);
666out:
667 return out;
668}
669
670/**
671 * ipcget - Common sys_*get() code
672 * @ns: namsepace
673 * @ids: ipc identifier set
674 * @ops: operations to be called on ipc object creation, permission checks
675 * and further checks
676 * @params: the parameters needed by the previous operations.
677 *
678 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
679 */
680int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
681 struct ipc_ops *ops, struct ipc_params *params)
682{
683 if (params->key == IPC_PRIVATE)
684 return ipcget_new(ns, ids, ops, params);
685 else
686 return ipcget_public(ns, ids, ops, params);
687}
688
689/**
690 * ipc_update_perm - update the permissions of an ipc object
691 * @in: the permission given as input.
692 * @out: the permission of the ipc to set.
693 */
694int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
695{
696 kuid_t uid = make_kuid(current_user_ns(), in->uid);
697 kgid_t gid = make_kgid(current_user_ns(), in->gid);
698 if (!uid_valid(uid) || !gid_valid(gid))
699 return -EINVAL;
700
701 out->uid = uid;
702 out->gid = gid;
703 out->mode = (out->mode & ~S_IRWXUGO)
704 | (in->mode & S_IRWXUGO);
705
706 return 0;
707}
708
709/**
710 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
711 * @ns: ipc namespace
712 * @ids: the table of ids where to look for the ipc
713 * @id: the id of the ipc to retrieve
714 * @cmd: the cmd to check
715 * @perm: the permission to set
716 * @extra_perm: one extra permission parameter used by msq
717 *
718 * This function does some common audit and permissions check for some IPC_XXX
719 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
720 * It must be called without any lock held and
721 * - retrieves the ipc with the given id in the given table.
722 * - performs some audit and permission check, depending on the given cmd
723 * - returns a pointer to the ipc object or otherwise, the corresponding error.
724 *
725 * Call holding the both the rwsem and the rcu read lock.
726 */
727struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
728 struct ipc_ids *ids, int id, int cmd,
729 struct ipc64_perm *perm, int extra_perm)
730{
731 kuid_t euid;
732 int err = -EPERM;
733 struct kern_ipc_perm *ipcp;
734
735 ipcp = ipc_obtain_object_check(ids, id);
736 if (IS_ERR(ipcp)) {
737 err = PTR_ERR(ipcp);
738 goto err;
739 }
740
741 audit_ipc_obj(ipcp);
742 if (cmd == IPC_SET)
743 audit_ipc_set_perm(extra_perm, perm->uid,
744 perm->gid, perm->mode);
745
746 euid = current_euid();
747 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
748 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
749 return ipcp; /* successful lookup */
750err:
751 return ERR_PTR(err);
752}
753
754#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
755
756
757/**
758 * ipc_parse_version - ipc call version
759 * @cmd: pointer to command
760 *
761 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
762 * The @cmd value is turned from an encoding command and version into
763 * just the command code.
764 */
765int ipc_parse_version(int *cmd)
766{
767 if (*cmd & IPC_64) {
768 *cmd ^= IPC_64;
769 return IPC_64;
770 } else {
771 return IPC_OLD;
772 }
773}
774
775#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
776
777#ifdef CONFIG_PROC_FS
778struct ipc_proc_iter {
779 struct ipc_namespace *ns;
780 struct ipc_proc_iface *iface;
781};
782
783/*
784 * This routine locks the ipc structure found at least at position pos.
785 */
786static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
787 loff_t *new_pos)
788{
789 struct kern_ipc_perm *ipc;
790 int total, id;
791
792 total = 0;
793 for (id = 0; id < pos && total < ids->in_use; id++) {
794 ipc = idr_find(&ids->ipcs_idr, id);
795 if (ipc != NULL)
796 total++;
797 }
798
799 if (total >= ids->in_use)
800 return NULL;
801
802 for (; pos < IPCMNI; pos++) {
803 ipc = idr_find(&ids->ipcs_idr, pos);
804 if (ipc != NULL) {
805 *new_pos = pos + 1;
806 rcu_read_lock();
807 ipc_lock_object(ipc);
808 return ipc;
809 }
810 }
811
812 /* Out of range - return NULL to terminate iteration */
813 return NULL;
814}
815
816static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
817{
818 struct ipc_proc_iter *iter = s->private;
819 struct ipc_proc_iface *iface = iter->iface;
820 struct kern_ipc_perm *ipc = it;
821
822 /* If we had an ipc id locked before, unlock it */
823 if (ipc && ipc != SEQ_START_TOKEN)
824 ipc_unlock(ipc);
825
826 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
827}
828
829/*
830 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
831 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
832 */
833static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
834{
835 struct ipc_proc_iter *iter = s->private;
836 struct ipc_proc_iface *iface = iter->iface;
837 struct ipc_ids *ids;
838
839 ids = &iter->ns->ids[iface->ids];
840
841 /*
842 * Take the lock - this will be released by the corresponding
843 * call to stop().
844 */
845 down_read(&ids->rwsem);
846
847 /* pos < 0 is invalid */
848 if (*pos < 0)
849 return NULL;
850
851 /* pos == 0 means header */
852 if (*pos == 0)
853 return SEQ_START_TOKEN;
854
855 /* Find the (pos-1)th ipc */
856 return sysvipc_find_ipc(ids, *pos - 1, pos);
857}
858
859static void sysvipc_proc_stop(struct seq_file *s, void *it)
860{
861 struct kern_ipc_perm *ipc = it;
862 struct ipc_proc_iter *iter = s->private;
863 struct ipc_proc_iface *iface = iter->iface;
864 struct ipc_ids *ids;
865
866 /* If we had a locked structure, release it */
867 if (ipc && ipc != SEQ_START_TOKEN)
868 ipc_unlock(ipc);
869
870 ids = &iter->ns->ids[iface->ids];
871 /* Release the lock we took in start() */
872 up_read(&ids->rwsem);
873}
874
875static int sysvipc_proc_show(struct seq_file *s, void *it)
876{
877 struct ipc_proc_iter *iter = s->private;
878 struct ipc_proc_iface *iface = iter->iface;
879
880 if (it == SEQ_START_TOKEN)
881 return seq_puts(s, iface->header);
882
883 return iface->show(s, it);
884}
885
886static const struct seq_operations sysvipc_proc_seqops = {
887 .start = sysvipc_proc_start,
888 .stop = sysvipc_proc_stop,
889 .next = sysvipc_proc_next,
890 .show = sysvipc_proc_show,
891};
892
893static int sysvipc_proc_open(struct inode *inode, struct file *file)
894{
895 int ret;
896 struct seq_file *seq;
897 struct ipc_proc_iter *iter;
898
899 ret = -ENOMEM;
900 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
901 if (!iter)
902 goto out;
903
904 ret = seq_open(file, &sysvipc_proc_seqops);
905 if (ret) {
906 kfree(iter);
907 goto out;
908 }
909
910 seq = file->private_data;
911 seq->private = iter;
912
913 iter->iface = PDE_DATA(inode);
914 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
915out:
916 return ret;
917}
918
919static int sysvipc_proc_release(struct inode *inode, struct file *file)
920{
921 struct seq_file *seq = file->private_data;
922 struct ipc_proc_iter *iter = seq->private;
923 put_ipc_ns(iter->ns);
924 return seq_release_private(inode, file);
925}
926
927static const struct file_operations sysvipc_proc_fops = {
928 .open = sysvipc_proc_open,
929 .read = seq_read,
930 .llseek = seq_lseek,
931 .release = sysvipc_proc_release,
932};
933#endif /* CONFIG_PROC_FS */