Loading...
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
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 */