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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#include <linux/log2.h>
68
69#include <asm/unistd.h>
70
71#include "util.h"
72
73struct ipc_proc_iface {
74 const char *path;
75 const char *header;
76 int ids;
77 int (*show)(struct seq_file *, void *);
78};
79
80/**
81 * ipc_init - initialise ipc subsystem
82 *
83 * The various sysv ipc resources (semaphores, messages and shared
84 * memory) are initialised.
85 *
86 * A callback routine is registered into the memory hotplug notifier
87 * chain: since msgmni scales to lowmem this callback routine will be
88 * called upon successful memory add / remove to recompute msmgni.
89 */
90static int __init ipc_init(void)
91{
92 proc_mkdir("sysvipc", NULL);
93 sem_init();
94 msg_init();
95 shm_init();
96
97 return 0;
98}
99device_initcall(ipc_init);
100
101static const struct rhashtable_params ipc_kht_params = {
102 .head_offset = offsetof(struct kern_ipc_perm, khtnode),
103 .key_offset = offsetof(struct kern_ipc_perm, key),
104 .key_len = sizeof_field(struct kern_ipc_perm, key),
105 .automatic_shrinking = true,
106};
107
108/**
109 * ipc_init_ids - initialise ipc identifiers
110 * @ids: ipc identifier set
111 *
112 * Set up the sequence range to use for the ipc identifier range (limited
113 * below ipc_mni) then initialise the keys hashtable and ids idr.
114 */
115void ipc_init_ids(struct ipc_ids *ids)
116{
117 ids->in_use = 0;
118 ids->seq = 0;
119 init_rwsem(&ids->rwsem);
120 rhashtable_init(&ids->key_ht, &ipc_kht_params);
121 idr_init(&ids->ipcs_idr);
122 ids->max_idx = -1;
123 ids->last_idx = -1;
124#ifdef CONFIG_CHECKPOINT_RESTORE
125 ids->next_id = -1;
126#endif
127}
128
129#ifdef CONFIG_PROC_FS
130static const struct proc_ops sysvipc_proc_ops;
131/**
132 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
133 * @path: Path in procfs
134 * @header: Banner to be printed at the beginning of the file.
135 * @ids: ipc id table to iterate.
136 * @show: show routine.
137 */
138void __init ipc_init_proc_interface(const char *path, const char *header,
139 int ids, int (*show)(struct seq_file *, void *))
140{
141 struct proc_dir_entry *pde;
142 struct ipc_proc_iface *iface;
143
144 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
145 if (!iface)
146 return;
147 iface->path = path;
148 iface->header = header;
149 iface->ids = ids;
150 iface->show = show;
151
152 pde = proc_create_data(path,
153 S_IRUGO, /* world readable */
154 NULL, /* parent dir */
155 &sysvipc_proc_ops,
156 iface);
157 if (!pde)
158 kfree(iface);
159}
160#endif
161
162/**
163 * ipc_findkey - find a key in an ipc identifier set
164 * @ids: ipc identifier set
165 * @key: key to find
166 *
167 * Returns the locked pointer to the ipc structure if found or NULL
168 * otherwise. If key is found ipc points to the owning ipc structure
169 *
170 * Called with writer ipc_ids.rwsem held.
171 */
172static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
173{
174 struct kern_ipc_perm *ipcp;
175
176 ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
177 ipc_kht_params);
178 if (!ipcp)
179 return NULL;
180
181 rcu_read_lock();
182 ipc_lock_object(ipcp);
183 return ipcp;
184}
185
186/*
187 * Insert new IPC object into idr tree, and set sequence number and id
188 * in the correct order.
189 * Especially:
190 * - the sequence number must be set before inserting the object into the idr,
191 * because the sequence number is accessed without a lock.
192 * - the id can/must be set after inserting the object into the idr.
193 * All accesses must be done after getting kern_ipc_perm.lock.
194 *
195 * The caller must own kern_ipc_perm.lock.of the new object.
196 * On error, the function returns a (negative) error code.
197 *
198 * To conserve sequence number space, especially with extended ipc_mni,
199 * the sequence number is incremented only when the returned ID is less than
200 * the last one.
201 */
202static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
203{
204 int idx, next_id = -1;
205
206#ifdef CONFIG_CHECKPOINT_RESTORE
207 next_id = ids->next_id;
208 ids->next_id = -1;
209#endif
210
211 /*
212 * As soon as a new object is inserted into the idr,
213 * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
214 * and the lockless preparations for ipc operations can start.
215 * This means especially: permission checks, audit calls, allocation
216 * of undo structures, ...
217 *
218 * Thus the object must be fully initialized, and if something fails,
219 * then the full tear-down sequence must be followed.
220 * (i.e.: set new->deleted, reduce refcount, call_rcu())
221 */
222
223 if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
224 int max_idx;
225
226 max_idx = max(ids->in_use*3/2, ipc_min_cycle);
227 max_idx = min(max_idx, ipc_mni);
228
229 /* allocate the idx, with a NULL struct kern_ipc_perm */
230 idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
231 GFP_NOWAIT);
232
233 if (idx >= 0) {
234 /*
235 * idx got allocated successfully.
236 * Now calculate the sequence number and set the
237 * pointer for real.
238 */
239 if (idx <= ids->last_idx) {
240 ids->seq++;
241 if (ids->seq >= ipcid_seq_max())
242 ids->seq = 0;
243 }
244 ids->last_idx = idx;
245
246 new->seq = ids->seq;
247 /* no need for smp_wmb(), this is done
248 * inside idr_replace, as part of
249 * rcu_assign_pointer
250 */
251 idr_replace(&ids->ipcs_idr, new, idx);
252 }
253 } else {
254 new->seq = ipcid_to_seqx(next_id);
255 idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
256 0, GFP_NOWAIT);
257 }
258 if (idx >= 0)
259 new->id = (new->seq << ipcmni_seq_shift()) + idx;
260 return idx;
261}
262
263/**
264 * ipc_addid - add an ipc identifier
265 * @ids: ipc identifier set
266 * @new: new ipc permission set
267 * @limit: limit for the number of used ids
268 *
269 * Add an entry 'new' to the ipc ids idr. The permissions object is
270 * initialised and the first free entry is set up and the index assigned
271 * is returned. The 'new' entry is returned in a locked state on success.
272 *
273 * On failure the entry is not locked and a negative err-code is returned.
274 * The caller must use ipc_rcu_putref() to free the identifier.
275 *
276 * Called with writer ipc_ids.rwsem held.
277 */
278int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
279{
280 kuid_t euid;
281 kgid_t egid;
282 int idx, err;
283
284 /* 1) Initialize the refcount so that ipc_rcu_putref works */
285 refcount_set(&new->refcount, 1);
286
287 if (limit > ipc_mni)
288 limit = ipc_mni;
289
290 if (ids->in_use >= limit)
291 return -ENOSPC;
292
293 idr_preload(GFP_KERNEL);
294
295 spin_lock_init(&new->lock);
296 rcu_read_lock();
297 spin_lock(&new->lock);
298
299 current_euid_egid(&euid, &egid);
300 new->cuid = new->uid = euid;
301 new->gid = new->cgid = egid;
302
303 new->deleted = false;
304
305 idx = ipc_idr_alloc(ids, new);
306 idr_preload_end();
307
308 if (idx >= 0 && new->key != IPC_PRIVATE) {
309 err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
310 ipc_kht_params);
311 if (err < 0) {
312 idr_remove(&ids->ipcs_idr, idx);
313 idx = err;
314 }
315 }
316 if (idx < 0) {
317 new->deleted = true;
318 spin_unlock(&new->lock);
319 rcu_read_unlock();
320 return idx;
321 }
322
323 ids->in_use++;
324 if (idx > ids->max_idx)
325 ids->max_idx = idx;
326 return idx;
327}
328
329/**
330 * ipcget_new - create a new ipc object
331 * @ns: ipc namespace
332 * @ids: ipc identifier set
333 * @ops: the actual creation routine to call
334 * @params: its parameters
335 *
336 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
337 * when the key is IPC_PRIVATE.
338 */
339static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
340 const struct ipc_ops *ops, struct ipc_params *params)
341{
342 int err;
343
344 down_write(&ids->rwsem);
345 err = ops->getnew(ns, params);
346 up_write(&ids->rwsem);
347 return err;
348}
349
350/**
351 * ipc_check_perms - check security and permissions for an ipc object
352 * @ns: ipc namespace
353 * @ipcp: ipc permission set
354 * @ops: the actual security routine to call
355 * @params: its parameters
356 *
357 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
358 * when the key is not IPC_PRIVATE and that key already exists in the
359 * ds IDR.
360 *
361 * On success, the ipc id is returned.
362 *
363 * It is called with ipc_ids.rwsem and ipcp->lock held.
364 */
365static int ipc_check_perms(struct ipc_namespace *ns,
366 struct kern_ipc_perm *ipcp,
367 const struct ipc_ops *ops,
368 struct ipc_params *params)
369{
370 int err;
371
372 if (ipcperms(ns, ipcp, params->flg))
373 err = -EACCES;
374 else {
375 err = ops->associate(ipcp, params->flg);
376 if (!err)
377 err = ipcp->id;
378 }
379
380 return err;
381}
382
383/**
384 * ipcget_public - get an ipc object or create a new one
385 * @ns: ipc namespace
386 * @ids: ipc identifier set
387 * @ops: the actual creation routine to call
388 * @params: its parameters
389 *
390 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
391 * when the key is not IPC_PRIVATE.
392 * It adds a new entry if the key is not found and does some permission
393 * / security checkings if the key is found.
394 *
395 * On success, the ipc id is returned.
396 */
397static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
398 const struct ipc_ops *ops, struct ipc_params *params)
399{
400 struct kern_ipc_perm *ipcp;
401 int flg = params->flg;
402 int err;
403
404 /*
405 * Take the lock as a writer since we are potentially going to add
406 * a new entry + read locks are not "upgradable"
407 */
408 down_write(&ids->rwsem);
409 ipcp = ipc_findkey(ids, params->key);
410 if (ipcp == NULL) {
411 /* key not used */
412 if (!(flg & IPC_CREAT))
413 err = -ENOENT;
414 else
415 err = ops->getnew(ns, params);
416 } else {
417 /* ipc object has been locked by ipc_findkey() */
418
419 if (flg & IPC_CREAT && flg & IPC_EXCL)
420 err = -EEXIST;
421 else {
422 err = 0;
423 if (ops->more_checks)
424 err = ops->more_checks(ipcp, params);
425 if (!err)
426 /*
427 * ipc_check_perms returns the IPC id on
428 * success
429 */
430 err = ipc_check_perms(ns, ipcp, ops, params);
431 }
432 ipc_unlock(ipcp);
433 }
434 up_write(&ids->rwsem);
435
436 return err;
437}
438
439/**
440 * ipc_kht_remove - remove an ipc from the key hashtable
441 * @ids: ipc identifier set
442 * @ipcp: ipc perm structure containing the key to remove
443 *
444 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
445 * before this function is called, and remain locked on the exit.
446 */
447static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
448{
449 if (ipcp->key != IPC_PRIVATE)
450 WARN_ON_ONCE(rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
451 ipc_kht_params));
452}
453
454/**
455 * ipc_search_maxidx - search for the highest assigned index
456 * @ids: ipc identifier set
457 * @limit: known upper limit for highest assigned index
458 *
459 * The function determines the highest assigned index in @ids. It is intended
460 * to be called when ids->max_idx needs to be updated.
461 * Updating ids->max_idx is necessary when the current highest index ipc
462 * object is deleted.
463 * If no ipc object is allocated, then -1 is returned.
464 *
465 * ipc_ids.rwsem needs to be held by the caller.
466 */
467static int ipc_search_maxidx(struct ipc_ids *ids, int limit)
468{
469 int tmpidx;
470 int i;
471 int retval;
472
473 i = ilog2(limit+1);
474
475 retval = 0;
476 for (; i >= 0; i--) {
477 tmpidx = retval | (1<<i);
478 /*
479 * "0" is a possible index value, thus search using
480 * e.g. 15,7,3,1,0 instead of 16,8,4,2,1.
481 */
482 tmpidx = tmpidx-1;
483 if (idr_get_next(&ids->ipcs_idr, &tmpidx))
484 retval |= (1<<i);
485 }
486 return retval - 1;
487}
488
489/**
490 * ipc_rmid - remove an ipc identifier
491 * @ids: ipc identifier set
492 * @ipcp: ipc perm structure containing the identifier to remove
493 *
494 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
495 * before this function is called, and remain locked on the exit.
496 */
497void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
498{
499 int idx = ipcid_to_idx(ipcp->id);
500
501 WARN_ON_ONCE(idr_remove(&ids->ipcs_idr, idx) != ipcp);
502 ipc_kht_remove(ids, ipcp);
503 ids->in_use--;
504 ipcp->deleted = true;
505
506 if (unlikely(idx == ids->max_idx)) {
507 idx = ids->max_idx-1;
508 if (idx >= 0)
509 idx = ipc_search_maxidx(ids, idx);
510 ids->max_idx = idx;
511 }
512}
513
514/**
515 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
516 * @ids: ipc identifier set
517 * @ipcp: ipc perm structure containing the key to modify
518 *
519 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
520 * before this function is called, and remain locked on the exit.
521 */
522void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
523{
524 ipc_kht_remove(ids, ipcp);
525 ipcp->key = IPC_PRIVATE;
526}
527
528bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
529{
530 return refcount_inc_not_zero(&ptr->refcount);
531}
532
533void ipc_rcu_putref(struct kern_ipc_perm *ptr,
534 void (*func)(struct rcu_head *head))
535{
536 if (!refcount_dec_and_test(&ptr->refcount))
537 return;
538
539 call_rcu(&ptr->rcu, func);
540}
541
542/**
543 * ipcperms - check ipc permissions
544 * @ns: ipc namespace
545 * @ipcp: ipc permission set
546 * @flag: desired permission set
547 *
548 * Check user, group, other permissions for access
549 * to ipc resources. return 0 if allowed
550 *
551 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
552 */
553int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
554{
555 kuid_t euid = current_euid();
556 int requested_mode, granted_mode;
557
558 audit_ipc_obj(ipcp);
559 requested_mode = (flag >> 6) | (flag >> 3) | flag;
560 granted_mode = ipcp->mode;
561 if (uid_eq(euid, ipcp->cuid) ||
562 uid_eq(euid, ipcp->uid))
563 granted_mode >>= 6;
564 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
565 granted_mode >>= 3;
566 /* is there some bit set in requested_mode but not in granted_mode? */
567 if ((requested_mode & ~granted_mode & 0007) &&
568 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
569 return -1;
570
571 return security_ipc_permission(ipcp, flag);
572}
573
574/*
575 * Functions to convert between the kern_ipc_perm structure and the
576 * old/new ipc_perm structures
577 */
578
579/**
580 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
581 * @in: kernel permissions
582 * @out: new style ipc permissions
583 *
584 * Turn the kernel object @in into a set of permissions descriptions
585 * for returning to userspace (@out).
586 */
587void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
588{
589 out->key = in->key;
590 out->uid = from_kuid_munged(current_user_ns(), in->uid);
591 out->gid = from_kgid_munged(current_user_ns(), in->gid);
592 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
593 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
594 out->mode = in->mode;
595 out->seq = in->seq;
596}
597
598/**
599 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
600 * @in: new style ipc permissions
601 * @out: old style ipc permissions
602 *
603 * Turn the new style permissions object @in into a compatibility
604 * object and store it into the @out pointer.
605 */
606void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
607{
608 out->key = in->key;
609 SET_UID(out->uid, in->uid);
610 SET_GID(out->gid, in->gid);
611 SET_UID(out->cuid, in->cuid);
612 SET_GID(out->cgid, in->cgid);
613 out->mode = in->mode;
614 out->seq = in->seq;
615}
616
617/**
618 * ipc_obtain_object_idr
619 * @ids: ipc identifier set
620 * @id: ipc id to look for
621 *
622 * Look for an id in the ipc ids idr and return associated ipc object.
623 *
624 * Call inside the RCU critical section.
625 * The ipc object is *not* locked on exit.
626 */
627struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
628{
629 struct kern_ipc_perm *out;
630 int idx = ipcid_to_idx(id);
631
632 out = idr_find(&ids->ipcs_idr, idx);
633 if (!out)
634 return ERR_PTR(-EINVAL);
635
636 return out;
637}
638
639/**
640 * ipc_obtain_object_check
641 * @ids: ipc identifier set
642 * @id: ipc id to look for
643 *
644 * Similar to ipc_obtain_object_idr() but also checks the ipc object
645 * sequence number.
646 *
647 * Call inside the RCU critical section.
648 * The ipc object is *not* locked on exit.
649 */
650struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
651{
652 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
653
654 if (IS_ERR(out))
655 goto out;
656
657 if (ipc_checkid(out, id))
658 return ERR_PTR(-EINVAL);
659out:
660 return out;
661}
662
663/**
664 * ipcget - Common sys_*get() code
665 * @ns: namespace
666 * @ids: ipc identifier set
667 * @ops: operations to be called on ipc object creation, permission checks
668 * and further checks
669 * @params: the parameters needed by the previous operations.
670 *
671 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
672 */
673int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
674 const struct ipc_ops *ops, struct ipc_params *params)
675{
676 if (params->key == IPC_PRIVATE)
677 return ipcget_new(ns, ids, ops, params);
678 else
679 return ipcget_public(ns, ids, ops, params);
680}
681
682/**
683 * ipc_update_perm - update the permissions of an ipc object
684 * @in: the permission given as input.
685 * @out: the permission of the ipc to set.
686 */
687int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
688{
689 kuid_t uid = make_kuid(current_user_ns(), in->uid);
690 kgid_t gid = make_kgid(current_user_ns(), in->gid);
691 if (!uid_valid(uid) || !gid_valid(gid))
692 return -EINVAL;
693
694 out->uid = uid;
695 out->gid = gid;
696 out->mode = (out->mode & ~S_IRWXUGO)
697 | (in->mode & S_IRWXUGO);
698
699 return 0;
700}
701
702/**
703 * ipcctl_obtain_check - retrieve an ipc object and check permissions
704 * @ns: ipc namespace
705 * @ids: the table of ids where to look for the ipc
706 * @id: the id of the ipc to retrieve
707 * @cmd: the cmd to check
708 * @perm: the permission to set
709 * @extra_perm: one extra permission parameter used by msq
710 *
711 * This function does some common audit and permissions check for some IPC_XXX
712 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
713 *
714 * It:
715 * - retrieves the ipc object with the given id in the given table.
716 * - performs some audit and permission check, depending on the given cmd
717 * - returns a pointer to the ipc object or otherwise, the corresponding
718 * error.
719 *
720 * Call holding the both the rwsem and the rcu read lock.
721 */
722struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
723 struct ipc_ids *ids, int id, int cmd,
724 struct ipc64_perm *perm, int extra_perm)
725{
726 kuid_t euid;
727 int err = -EPERM;
728 struct kern_ipc_perm *ipcp;
729
730 ipcp = ipc_obtain_object_check(ids, id);
731 if (IS_ERR(ipcp)) {
732 err = PTR_ERR(ipcp);
733 goto err;
734 }
735
736 audit_ipc_obj(ipcp);
737 if (cmd == IPC_SET)
738 audit_ipc_set_perm(extra_perm, perm->uid,
739 perm->gid, perm->mode);
740
741 euid = current_euid();
742 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
743 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
744 return ipcp; /* successful lookup */
745err:
746 return ERR_PTR(err);
747}
748
749#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
750
751
752/**
753 * ipc_parse_version - ipc call version
754 * @cmd: pointer to command
755 *
756 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
757 * The @cmd value is turned from an encoding command and version into
758 * just the command code.
759 */
760int ipc_parse_version(int *cmd)
761{
762 if (*cmd & IPC_64) {
763 *cmd ^= IPC_64;
764 return IPC_64;
765 } else {
766 return IPC_OLD;
767 }
768}
769
770#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
771
772#ifdef CONFIG_PROC_FS
773struct ipc_proc_iter {
774 struct ipc_namespace *ns;
775 struct pid_namespace *pid_ns;
776 struct ipc_proc_iface *iface;
777};
778
779struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
780{
781 struct ipc_proc_iter *iter = s->private;
782 return iter->pid_ns;
783}
784
785/**
786 * sysvipc_find_ipc - Find and lock the ipc structure based on seq pos
787 * @ids: ipc identifier set
788 * @pos: expected position
789 *
790 * The function finds an ipc structure, based on the sequence file
791 * position @pos. If there is no ipc structure at position @pos, then
792 * the successor is selected.
793 * If a structure is found, then it is locked (both rcu_read_lock() and
794 * ipc_lock_object()) and @pos is set to the position needed to locate
795 * the found ipc structure.
796 * If nothing is found (i.e. EOF), @pos is not modified.
797 *
798 * The function returns the found ipc structure, or NULL at EOF.
799 */
800static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos)
801{
802 int tmpidx;
803 struct kern_ipc_perm *ipc;
804
805 /* convert from position to idr index -> "-1" */
806 tmpidx = *pos - 1;
807
808 ipc = idr_get_next(&ids->ipcs_idr, &tmpidx);
809 if (ipc != NULL) {
810 rcu_read_lock();
811 ipc_lock_object(ipc);
812
813 /* convert from idr index to position -> "+1" */
814 *pos = tmpidx + 1;
815 }
816 return ipc;
817}
818
819static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
820{
821 struct ipc_proc_iter *iter = s->private;
822 struct ipc_proc_iface *iface = iter->iface;
823 struct kern_ipc_perm *ipc = it;
824
825 /* If we had an ipc id locked before, unlock it */
826 if (ipc && ipc != SEQ_START_TOKEN)
827 ipc_unlock(ipc);
828
829 /* Next -> search for *pos+1 */
830 (*pos)++;
831 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos);
832}
833
834/*
835 * File positions: pos 0 -> header, pos n -> ipc idx = n - 1.
836 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
837 */
838static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
839{
840 struct ipc_proc_iter *iter = s->private;
841 struct ipc_proc_iface *iface = iter->iface;
842 struct ipc_ids *ids;
843
844 ids = &iter->ns->ids[iface->ids];
845
846 /*
847 * Take the lock - this will be released by the corresponding
848 * call to stop().
849 */
850 down_read(&ids->rwsem);
851
852 /* pos < 0 is invalid */
853 if (*pos < 0)
854 return NULL;
855
856 /* pos == 0 means header */
857 if (*pos == 0)
858 return SEQ_START_TOKEN;
859
860 /* Otherwise return the correct ipc structure */
861 return sysvipc_find_ipc(ids, pos);
862}
863
864static void sysvipc_proc_stop(struct seq_file *s, void *it)
865{
866 struct kern_ipc_perm *ipc = it;
867 struct ipc_proc_iter *iter = s->private;
868 struct ipc_proc_iface *iface = iter->iface;
869 struct ipc_ids *ids;
870
871 /* If we had a locked structure, release it */
872 if (ipc && ipc != SEQ_START_TOKEN)
873 ipc_unlock(ipc);
874
875 ids = &iter->ns->ids[iface->ids];
876 /* Release the lock we took in start() */
877 up_read(&ids->rwsem);
878}
879
880static int sysvipc_proc_show(struct seq_file *s, void *it)
881{
882 struct ipc_proc_iter *iter = s->private;
883 struct ipc_proc_iface *iface = iter->iface;
884
885 if (it == SEQ_START_TOKEN) {
886 seq_puts(s, iface->header);
887 return 0;
888 }
889
890 return iface->show(s, it);
891}
892
893static const struct seq_operations sysvipc_proc_seqops = {
894 .start = sysvipc_proc_start,
895 .stop = sysvipc_proc_stop,
896 .next = sysvipc_proc_next,
897 .show = sysvipc_proc_show,
898};
899
900static int sysvipc_proc_open(struct inode *inode, struct file *file)
901{
902 struct ipc_proc_iter *iter;
903
904 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
905 if (!iter)
906 return -ENOMEM;
907
908 iter->iface = pde_data(inode);
909 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
910 iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
911
912 return 0;
913}
914
915static int sysvipc_proc_release(struct inode *inode, struct file *file)
916{
917 struct seq_file *seq = file->private_data;
918 struct ipc_proc_iter *iter = seq->private;
919 put_ipc_ns(iter->ns);
920 put_pid_ns(iter->pid_ns);
921 return seq_release_private(inode, file);
922}
923
924static const struct proc_ops sysvipc_proc_ops = {
925 .proc_flags = PROC_ENTRY_PERMANENT,
926 .proc_open = sysvipc_proc_open,
927 .proc_read = seq_read,
928 .proc_lseek = seq_lseek,
929 .proc_release = sysvipc_proc_release,
930};
931#endif /* CONFIG_PROC_FS */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/ipc/util.c
4 * Copyright (C) 1992 Krishna Balasubramanian
5 *
6 * Sep 1997 - Call suser() last after "normal" permission checks so we
7 * get BSD style process accounting right.
8 * Occurs in several places in the IPC code.
9 * Chris Evans, <chris@ferret.lmh.ox.ac.uk>
10 * Nov 1999 - ipc helper functions, unified SMP locking
11 * Manfred Spraul <manfred@colorfullife.com>
12 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
13 * Mingming Cao <cmm@us.ibm.com>
14 * Mar 2006 - support for audit of ipc object properties
15 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
16 * Jun 2006 - namespaces ssupport
17 * OpenVZ, SWsoft Inc.
18 * Pavel Emelianov <xemul@openvz.org>
19 *
20 * General sysv ipc locking scheme:
21 * rcu_read_lock()
22 * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
23 * tree.
24 * - perform initial checks (capabilities, auditing and permission,
25 * etc).
26 * - perform read-only operations, such as INFO command, that
27 * do not demand atomicity
28 * acquire the ipc lock (kern_ipc_perm.lock) through
29 * ipc_lock_object()
30 * - perform read-only operations that demand atomicity,
31 * such as STAT command.
32 * - perform data updates, such as SET, RMID commands and
33 * mechanism-specific operations (semop/semtimedop,
34 * msgsnd/msgrcv, shmat/shmdt).
35 * drop the ipc lock, through ipc_unlock_object().
36 * rcu_read_unlock()
37 *
38 * The ids->rwsem must be taken when:
39 * - creating, removing and iterating the existing entries in ipc
40 * identifier sets.
41 * - iterating through files under /proc/sysvipc/
42 *
43 * Note that sems have a special fast path that avoids kern_ipc_perm.lock -
44 * see sem_lock().
45 */
46
47#include <linux/mm.h>
48#include <linux/shm.h>
49#include <linux/init.h>
50#include <linux/msg.h>
51#include <linux/vmalloc.h>
52#include <linux/slab.h>
53#include <linux/notifier.h>
54#include <linux/capability.h>
55#include <linux/highuid.h>
56#include <linux/security.h>
57#include <linux/rcupdate.h>
58#include <linux/workqueue.h>
59#include <linux/seq_file.h>
60#include <linux/proc_fs.h>
61#include <linux/audit.h>
62#include <linux/nsproxy.h>
63#include <linux/rwsem.h>
64#include <linux/memory.h>
65#include <linux/ipc_namespace.h>
66
67#include <asm/unistd.h>
68
69#include "util.h"
70
71struct ipc_proc_iface {
72 const char *path;
73 const char *header;
74 int ids;
75 int (*show)(struct seq_file *, void *);
76};
77
78/**
79 * ipc_init - initialise ipc subsystem
80 *
81 * The various sysv ipc resources (semaphores, messages and shared
82 * memory) are initialised.
83 *
84 * A callback routine is registered into the memory hotplug notifier
85 * chain: since msgmni scales to lowmem this callback routine will be
86 * called upon successful memory add / remove to recompute msmgni.
87 */
88static int __init ipc_init(void)
89{
90 int err_sem, err_msg;
91
92 proc_mkdir("sysvipc", NULL);
93 err_sem = sem_init();
94 WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem);
95 err_msg = msg_init();
96 WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg);
97 shm_init();
98
99 return err_msg ? err_msg : err_sem;
100}
101device_initcall(ipc_init);
102
103static const struct rhashtable_params ipc_kht_params = {
104 .head_offset = offsetof(struct kern_ipc_perm, khtnode),
105 .key_offset = offsetof(struct kern_ipc_perm, key),
106 .key_len = FIELD_SIZEOF(struct kern_ipc_perm, key),
107 .locks_mul = 1,
108 .automatic_shrinking = true,
109};
110
111/**
112 * ipc_init_ids - initialise ipc identifiers
113 * @ids: ipc identifier set
114 *
115 * Set up the sequence range to use for the ipc identifier range (limited
116 * below IPCMNI) then initialise the keys hashtable and ids idr.
117 */
118int ipc_init_ids(struct ipc_ids *ids)
119{
120 int err;
121 ids->in_use = 0;
122 ids->seq = 0;
123 init_rwsem(&ids->rwsem);
124 err = rhashtable_init(&ids->key_ht, &ipc_kht_params);
125 if (err)
126 return err;
127 idr_init(&ids->ipcs_idr);
128 ids->tables_initialized = true;
129 ids->max_id = -1;
130#ifdef CONFIG_CHECKPOINT_RESTORE
131 ids->next_id = -1;
132#endif
133 return 0;
134}
135
136#ifdef CONFIG_PROC_FS
137static const struct file_operations sysvipc_proc_fops;
138/**
139 * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
140 * @path: Path in procfs
141 * @header: Banner to be printed at the beginning of the file.
142 * @ids: ipc id table to iterate.
143 * @show: show routine.
144 */
145void __init ipc_init_proc_interface(const char *path, const char *header,
146 int ids, int (*show)(struct seq_file *, void *))
147{
148 struct proc_dir_entry *pde;
149 struct ipc_proc_iface *iface;
150
151 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
152 if (!iface)
153 return;
154 iface->path = path;
155 iface->header = header;
156 iface->ids = ids;
157 iface->show = show;
158
159 pde = proc_create_data(path,
160 S_IRUGO, /* world readable */
161 NULL, /* parent dir */
162 &sysvipc_proc_fops,
163 iface);
164 if (!pde)
165 kfree(iface);
166}
167#endif
168
169/**
170 * ipc_findkey - find a key in an ipc identifier set
171 * @ids: ipc identifier set
172 * @key: key to find
173 *
174 * Returns the locked pointer to the ipc structure if found or NULL
175 * otherwise. If key is found ipc points to the owning ipc structure
176 *
177 * Called with writer ipc_ids.rwsem held.
178 */
179static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
180{
181 struct kern_ipc_perm *ipcp = NULL;
182
183 if (likely(ids->tables_initialized))
184 ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
185 ipc_kht_params);
186
187 if (ipcp) {
188 rcu_read_lock();
189 ipc_lock_object(ipcp);
190 return ipcp;
191 }
192
193 return NULL;
194}
195
196#ifdef CONFIG_CHECKPOINT_RESTORE
197/*
198 * Specify desired id for next allocated IPC object.
199 */
200#define ipc_idr_alloc(ids, new) \
201 idr_alloc(&(ids)->ipcs_idr, (new), \
202 (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\
203 0, GFP_NOWAIT)
204
205static inline int ipc_buildid(int id, struct ipc_ids *ids,
206 struct kern_ipc_perm *new)
207{
208 if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */
209 new->seq = ids->seq++;
210 if (ids->seq > IPCID_SEQ_MAX)
211 ids->seq = 0;
212 } else {
213 new->seq = ipcid_to_seqx(ids->next_id);
214 ids->next_id = -1;
215 }
216
217 return SEQ_MULTIPLIER * new->seq + id;
218}
219
220#else
221#define ipc_idr_alloc(ids, new) \
222 idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT)
223
224static inline int ipc_buildid(int id, struct ipc_ids *ids,
225 struct kern_ipc_perm *new)
226{
227 new->seq = ids->seq++;
228 if (ids->seq > IPCID_SEQ_MAX)
229 ids->seq = 0;
230
231 return SEQ_MULTIPLIER * new->seq + id;
232}
233
234#endif /* CONFIG_CHECKPOINT_RESTORE */
235
236/**
237 * ipc_addid - add an ipc identifier
238 * @ids: ipc identifier set
239 * @new: new ipc permission set
240 * @limit: limit for the number of used ids
241 *
242 * Add an entry 'new' to the ipc ids idr. The permissions object is
243 * initialised and the first free entry is set up and the id assigned
244 * is returned. The 'new' entry is returned in a locked state on success.
245 * On failure the entry is not locked and a negative err-code is returned.
246 *
247 * Called with writer ipc_ids.rwsem held.
248 */
249int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
250{
251 kuid_t euid;
252 kgid_t egid;
253 int id, err;
254
255 if (limit > IPCMNI)
256 limit = IPCMNI;
257
258 if (!ids->tables_initialized || ids->in_use >= limit)
259 return -ENOSPC;
260
261 idr_preload(GFP_KERNEL);
262
263 refcount_set(&new->refcount, 1);
264 spin_lock_init(&new->lock);
265 new->deleted = false;
266 rcu_read_lock();
267 spin_lock(&new->lock);
268
269 current_euid_egid(&euid, &egid);
270 new->cuid = new->uid = euid;
271 new->gid = new->cgid = egid;
272
273 id = ipc_idr_alloc(ids, new);
274 idr_preload_end();
275
276 if (id >= 0 && new->key != IPC_PRIVATE) {
277 err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
278 ipc_kht_params);
279 if (err < 0) {
280 idr_remove(&ids->ipcs_idr, id);
281 id = err;
282 }
283 }
284 if (id < 0) {
285 spin_unlock(&new->lock);
286 rcu_read_unlock();
287 return id;
288 }
289
290 ids->in_use++;
291 if (id > ids->max_id)
292 ids->max_id = id;
293
294 new->id = ipc_buildid(id, ids, new);
295
296 return id;
297}
298
299/**
300 * ipcget_new - create a new ipc object
301 * @ns: ipc namespace
302 * @ids: ipc identifier set
303 * @ops: the actual creation routine to call
304 * @params: its parameters
305 *
306 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
307 * when the key is IPC_PRIVATE.
308 */
309static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
310 const struct ipc_ops *ops, struct ipc_params *params)
311{
312 int err;
313
314 down_write(&ids->rwsem);
315 err = ops->getnew(ns, params);
316 up_write(&ids->rwsem);
317 return err;
318}
319
320/**
321 * ipc_check_perms - check security and permissions for an ipc object
322 * @ns: ipc namespace
323 * @ipcp: ipc permission set
324 * @ops: the actual security routine to call
325 * @params: its parameters
326 *
327 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
328 * when the key is not IPC_PRIVATE and that key already exists in the
329 * ds IDR.
330 *
331 * On success, the ipc id is returned.
332 *
333 * It is called with ipc_ids.rwsem and ipcp->lock held.
334 */
335static int ipc_check_perms(struct ipc_namespace *ns,
336 struct kern_ipc_perm *ipcp,
337 const struct ipc_ops *ops,
338 struct ipc_params *params)
339{
340 int err;
341
342 if (ipcperms(ns, ipcp, params->flg))
343 err = -EACCES;
344 else {
345 err = ops->associate(ipcp, params->flg);
346 if (!err)
347 err = ipcp->id;
348 }
349
350 return err;
351}
352
353/**
354 * ipcget_public - get an ipc object or create a new one
355 * @ns: ipc namespace
356 * @ids: ipc identifier set
357 * @ops: the actual creation routine to call
358 * @params: its parameters
359 *
360 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
361 * when the key is not IPC_PRIVATE.
362 * It adds a new entry if the key is not found and does some permission
363 * / security checkings if the key is found.
364 *
365 * On success, the ipc id is returned.
366 */
367static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
368 const struct ipc_ops *ops, struct ipc_params *params)
369{
370 struct kern_ipc_perm *ipcp;
371 int flg = params->flg;
372 int err;
373
374 /*
375 * Take the lock as a writer since we are potentially going to add
376 * a new entry + read locks are not "upgradable"
377 */
378 down_write(&ids->rwsem);
379 ipcp = ipc_findkey(ids, params->key);
380 if (ipcp == NULL) {
381 /* key not used */
382 if (!(flg & IPC_CREAT))
383 err = -ENOENT;
384 else
385 err = ops->getnew(ns, params);
386 } else {
387 /* ipc object has been locked by ipc_findkey() */
388
389 if (flg & IPC_CREAT && flg & IPC_EXCL)
390 err = -EEXIST;
391 else {
392 err = 0;
393 if (ops->more_checks)
394 err = ops->more_checks(ipcp, params);
395 if (!err)
396 /*
397 * ipc_check_perms returns the IPC id on
398 * success
399 */
400 err = ipc_check_perms(ns, ipcp, ops, params);
401 }
402 ipc_unlock(ipcp);
403 }
404 up_write(&ids->rwsem);
405
406 return err;
407}
408
409/**
410 * ipc_kht_remove - remove an ipc from the key hashtable
411 * @ids: ipc identifier set
412 * @ipcp: ipc perm structure containing the key to remove
413 *
414 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
415 * before this function is called, and remain locked on the exit.
416 */
417static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
418{
419 if (ipcp->key != IPC_PRIVATE)
420 rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
421 ipc_kht_params);
422}
423
424/**
425 * ipc_rmid - remove an ipc identifier
426 * @ids: ipc identifier set
427 * @ipcp: ipc perm structure containing the identifier to remove
428 *
429 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
430 * before this function is called, and remain locked on the exit.
431 */
432void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
433{
434 int lid = ipcid_to_idx(ipcp->id);
435
436 idr_remove(&ids->ipcs_idr, lid);
437 ipc_kht_remove(ids, ipcp);
438 ids->in_use--;
439 ipcp->deleted = true;
440
441 if (unlikely(lid == ids->max_id)) {
442 do {
443 lid--;
444 if (lid == -1)
445 break;
446 } while (!idr_find(&ids->ipcs_idr, lid));
447 ids->max_id = lid;
448 }
449}
450
451/**
452 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
453 * @ids: ipc identifier set
454 * @ipcp: ipc perm structure containing the key to modify
455 *
456 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
457 * before this function is called, and remain locked on the exit.
458 */
459void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
460{
461 ipc_kht_remove(ids, ipcp);
462 ipcp->key = IPC_PRIVATE;
463}
464
465int ipc_rcu_getref(struct kern_ipc_perm *ptr)
466{
467 return refcount_inc_not_zero(&ptr->refcount);
468}
469
470void ipc_rcu_putref(struct kern_ipc_perm *ptr,
471 void (*func)(struct rcu_head *head))
472{
473 if (!refcount_dec_and_test(&ptr->refcount))
474 return;
475
476 call_rcu(&ptr->rcu, func);
477}
478
479/**
480 * ipcperms - check ipc permissions
481 * @ns: ipc namespace
482 * @ipcp: ipc permission set
483 * @flag: desired permission set
484 *
485 * Check user, group, other permissions for access
486 * to ipc resources. return 0 if allowed
487 *
488 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
489 */
490int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
491{
492 kuid_t euid = current_euid();
493 int requested_mode, granted_mode;
494
495 audit_ipc_obj(ipcp);
496 requested_mode = (flag >> 6) | (flag >> 3) | flag;
497 granted_mode = ipcp->mode;
498 if (uid_eq(euid, ipcp->cuid) ||
499 uid_eq(euid, ipcp->uid))
500 granted_mode >>= 6;
501 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
502 granted_mode >>= 3;
503 /* is there some bit set in requested_mode but not in granted_mode? */
504 if ((requested_mode & ~granted_mode & 0007) &&
505 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
506 return -1;
507
508 return security_ipc_permission(ipcp, flag);
509}
510
511/*
512 * Functions to convert between the kern_ipc_perm structure and the
513 * old/new ipc_perm structures
514 */
515
516/**
517 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
518 * @in: kernel permissions
519 * @out: new style ipc permissions
520 *
521 * Turn the kernel object @in into a set of permissions descriptions
522 * for returning to userspace (@out).
523 */
524void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
525{
526 out->key = in->key;
527 out->uid = from_kuid_munged(current_user_ns(), in->uid);
528 out->gid = from_kgid_munged(current_user_ns(), in->gid);
529 out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
530 out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
531 out->mode = in->mode;
532 out->seq = in->seq;
533}
534
535/**
536 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
537 * @in: new style ipc permissions
538 * @out: old style ipc permissions
539 *
540 * Turn the new style permissions object @in into a compatibility
541 * object and store it into the @out pointer.
542 */
543void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
544{
545 out->key = in->key;
546 SET_UID(out->uid, in->uid);
547 SET_GID(out->gid, in->gid);
548 SET_UID(out->cuid, in->cuid);
549 SET_GID(out->cgid, in->cgid);
550 out->mode = in->mode;
551 out->seq = in->seq;
552}
553
554/**
555 * ipc_obtain_object_idr
556 * @ids: ipc identifier set
557 * @id: ipc id to look for
558 *
559 * Look for an id in the ipc ids idr and return associated ipc object.
560 *
561 * Call inside the RCU critical section.
562 * The ipc object is *not* locked on exit.
563 */
564struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
565{
566 struct kern_ipc_perm *out;
567 int lid = ipcid_to_idx(id);
568
569 if (unlikely(!ids->tables_initialized))
570 return ERR_PTR(-EINVAL);
571
572 out = idr_find(&ids->ipcs_idr, lid);
573 if (!out)
574 return ERR_PTR(-EINVAL);
575
576 return out;
577}
578
579/**
580 * ipc_lock - lock an ipc structure without rwsem held
581 * @ids: ipc identifier set
582 * @id: ipc id to look for
583 *
584 * Look for an id in the ipc ids idr and lock the associated ipc object.
585 *
586 * The ipc object is locked on successful exit.
587 */
588struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
589{
590 struct kern_ipc_perm *out;
591
592 rcu_read_lock();
593 out = ipc_obtain_object_idr(ids, id);
594 if (IS_ERR(out))
595 goto err;
596
597 spin_lock(&out->lock);
598
599 /*
600 * ipc_rmid() may have already freed the ID while ipc_lock()
601 * was spinning: here verify that the structure is still valid.
602 * Upon races with RMID, return -EIDRM, thus indicating that
603 * the ID points to a removed identifier.
604 */
605 if (ipc_valid_object(out))
606 return out;
607
608 spin_unlock(&out->lock);
609 out = ERR_PTR(-EIDRM);
610err:
611 rcu_read_unlock();
612 return out;
613}
614
615/**
616 * ipc_obtain_object_check
617 * @ids: ipc identifier set
618 * @id: ipc id to look for
619 *
620 * Similar to ipc_obtain_object_idr() but also checks
621 * the ipc object reference counter.
622 *
623 * Call inside the RCU critical section.
624 * The ipc object is *not* locked on exit.
625 */
626struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
627{
628 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
629
630 if (IS_ERR(out))
631 goto out;
632
633 if (ipc_checkid(out, id))
634 return ERR_PTR(-EINVAL);
635out:
636 return out;
637}
638
639/**
640 * ipcget - Common sys_*get() code
641 * @ns: namespace
642 * @ids: ipc identifier set
643 * @ops: operations to be called on ipc object creation, permission checks
644 * and further checks
645 * @params: the parameters needed by the previous operations.
646 *
647 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
648 */
649int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
650 const struct ipc_ops *ops, struct ipc_params *params)
651{
652 if (params->key == IPC_PRIVATE)
653 return ipcget_new(ns, ids, ops, params);
654 else
655 return ipcget_public(ns, ids, ops, params);
656}
657
658/**
659 * ipc_update_perm - update the permissions of an ipc object
660 * @in: the permission given as input.
661 * @out: the permission of the ipc to set.
662 */
663int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
664{
665 kuid_t uid = make_kuid(current_user_ns(), in->uid);
666 kgid_t gid = make_kgid(current_user_ns(), in->gid);
667 if (!uid_valid(uid) || !gid_valid(gid))
668 return -EINVAL;
669
670 out->uid = uid;
671 out->gid = gid;
672 out->mode = (out->mode & ~S_IRWXUGO)
673 | (in->mode & S_IRWXUGO);
674
675 return 0;
676}
677
678/**
679 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
680 * @ns: ipc namespace
681 * @ids: the table of ids where to look for the ipc
682 * @id: the id of the ipc to retrieve
683 * @cmd: the cmd to check
684 * @perm: the permission to set
685 * @extra_perm: one extra permission parameter used by msq
686 *
687 * This function does some common audit and permissions check for some IPC_XXX
688 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
689 * It must be called without any lock held and:
690 *
691 * - retrieves the ipc with the given id in the given table.
692 * - performs some audit and permission check, depending on the given cmd
693 * - returns a pointer to the ipc object or otherwise, the corresponding
694 * error.
695 *
696 * Call holding the both the rwsem and the rcu read lock.
697 */
698struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
699 struct ipc_ids *ids, int id, int cmd,
700 struct ipc64_perm *perm, int extra_perm)
701{
702 kuid_t euid;
703 int err = -EPERM;
704 struct kern_ipc_perm *ipcp;
705
706 ipcp = ipc_obtain_object_check(ids, id);
707 if (IS_ERR(ipcp)) {
708 err = PTR_ERR(ipcp);
709 goto err;
710 }
711
712 audit_ipc_obj(ipcp);
713 if (cmd == IPC_SET)
714 audit_ipc_set_perm(extra_perm, perm->uid,
715 perm->gid, perm->mode);
716
717 euid = current_euid();
718 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
719 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
720 return ipcp; /* successful lookup */
721err:
722 return ERR_PTR(err);
723}
724
725#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
726
727
728/**
729 * ipc_parse_version - ipc call version
730 * @cmd: pointer to command
731 *
732 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
733 * The @cmd value is turned from an encoding command and version into
734 * just the command code.
735 */
736int ipc_parse_version(int *cmd)
737{
738 if (*cmd & IPC_64) {
739 *cmd ^= IPC_64;
740 return IPC_64;
741 } else {
742 return IPC_OLD;
743 }
744}
745
746#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
747
748#ifdef CONFIG_PROC_FS
749struct ipc_proc_iter {
750 struct ipc_namespace *ns;
751 struct pid_namespace *pid_ns;
752 struct ipc_proc_iface *iface;
753};
754
755struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
756{
757 struct ipc_proc_iter *iter = s->private;
758 return iter->pid_ns;
759}
760
761/*
762 * This routine locks the ipc structure found at least at position pos.
763 */
764static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
765 loff_t *new_pos)
766{
767 struct kern_ipc_perm *ipc;
768 int total, id;
769
770 total = 0;
771 for (id = 0; id < pos && total < ids->in_use; id++) {
772 ipc = idr_find(&ids->ipcs_idr, id);
773 if (ipc != NULL)
774 total++;
775 }
776
777 if (total >= ids->in_use)
778 return NULL;
779
780 for (; pos < IPCMNI; pos++) {
781 ipc = idr_find(&ids->ipcs_idr, pos);
782 if (ipc != NULL) {
783 *new_pos = pos + 1;
784 rcu_read_lock();
785 ipc_lock_object(ipc);
786 return ipc;
787 }
788 }
789
790 /* Out of range - return NULL to terminate iteration */
791 return NULL;
792}
793
794static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
795{
796 struct ipc_proc_iter *iter = s->private;
797 struct ipc_proc_iface *iface = iter->iface;
798 struct kern_ipc_perm *ipc = it;
799
800 /* If we had an ipc id locked before, unlock it */
801 if (ipc && ipc != SEQ_START_TOKEN)
802 ipc_unlock(ipc);
803
804 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
805}
806
807/*
808 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
809 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
810 */
811static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
812{
813 struct ipc_proc_iter *iter = s->private;
814 struct ipc_proc_iface *iface = iter->iface;
815 struct ipc_ids *ids;
816
817 ids = &iter->ns->ids[iface->ids];
818
819 /*
820 * Take the lock - this will be released by the corresponding
821 * call to stop().
822 */
823 down_read(&ids->rwsem);
824
825 /* pos < 0 is invalid */
826 if (*pos < 0)
827 return NULL;
828
829 /* pos == 0 means header */
830 if (*pos == 0)
831 return SEQ_START_TOKEN;
832
833 /* Find the (pos-1)th ipc */
834 return sysvipc_find_ipc(ids, *pos - 1, pos);
835}
836
837static void sysvipc_proc_stop(struct seq_file *s, void *it)
838{
839 struct kern_ipc_perm *ipc = it;
840 struct ipc_proc_iter *iter = s->private;
841 struct ipc_proc_iface *iface = iter->iface;
842 struct ipc_ids *ids;
843
844 /* If we had a locked structure, release it */
845 if (ipc && ipc != SEQ_START_TOKEN)
846 ipc_unlock(ipc);
847
848 ids = &iter->ns->ids[iface->ids];
849 /* Release the lock we took in start() */
850 up_read(&ids->rwsem);
851}
852
853static int sysvipc_proc_show(struct seq_file *s, void *it)
854{
855 struct ipc_proc_iter *iter = s->private;
856 struct ipc_proc_iface *iface = iter->iface;
857
858 if (it == SEQ_START_TOKEN) {
859 seq_puts(s, iface->header);
860 return 0;
861 }
862
863 return iface->show(s, it);
864}
865
866static const struct seq_operations sysvipc_proc_seqops = {
867 .start = sysvipc_proc_start,
868 .stop = sysvipc_proc_stop,
869 .next = sysvipc_proc_next,
870 .show = sysvipc_proc_show,
871};
872
873static int sysvipc_proc_open(struct inode *inode, struct file *file)
874{
875 struct ipc_proc_iter *iter;
876
877 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
878 if (!iter)
879 return -ENOMEM;
880
881 iter->iface = PDE_DATA(inode);
882 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
883 iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
884
885 return 0;
886}
887
888static int sysvipc_proc_release(struct inode *inode, struct file *file)
889{
890 struct seq_file *seq = file->private_data;
891 struct ipc_proc_iter *iter = seq->private;
892 put_ipc_ns(iter->ns);
893 put_pid_ns(iter->pid_ns);
894 return seq_release_private(inode, file);
895}
896
897static const struct file_operations sysvipc_proc_fops = {
898 .open = sysvipc_proc_open,
899 .read = seq_read,
900 .llseek = seq_lseek,
901 .release = sysvipc_proc_release,
902};
903#endif /* CONFIG_PROC_FS */