util.c revision 0eb71a9d
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	int err_sem, err_msg;
92
93	proc_mkdir("sysvipc", NULL);
94	err_sem = sem_init();
95	WARN(err_sem, "ipc: sysv sem_init failed: %d\n", err_sem);
96	err_msg = msg_init();
97	WARN(err_msg, "ipc: sysv msg_init failed: %d\n", err_msg);
98	shm_init();
99
100	return err_msg ? err_msg : err_sem;
101}
102device_initcall(ipc_init);
103
104static const struct rhashtable_params ipc_kht_params = {
105	.head_offset		= offsetof(struct kern_ipc_perm, khtnode),
106	.key_offset		= offsetof(struct kern_ipc_perm, key),
107	.key_len		= FIELD_SIZEOF(struct kern_ipc_perm, key),
108	.locks_mul		= 1,
109	.automatic_shrinking	= true,
110};
111
112/**
113 * ipc_init_ids	- initialise ipc identifiers
114 * @ids: ipc identifier set
115 *
116 * Set up the sequence range to use for the ipc identifier range (limited
117 * below IPCMNI) then initialise the keys hashtable and ids idr.
118 */
119int ipc_init_ids(struct ipc_ids *ids)
120{
121	int err;
122	ids->in_use = 0;
123	ids->seq = 0;
124	init_rwsem(&ids->rwsem);
125	err = rhashtable_init(&ids->key_ht, &ipc_kht_params);
126	if (err)
127		return err;
128	idr_init(&ids->ipcs_idr);
129	ids->tables_initialized = true;
130	ids->max_id = -1;
131#ifdef CONFIG_CHECKPOINT_RESTORE
132	ids->next_id = -1;
133#endif
134	return 0;
135}
136
137#ifdef CONFIG_PROC_FS
138static const struct file_operations sysvipc_proc_fops;
139/**
140 * ipc_init_proc_interface -  create a proc interface for sysipc types using a seq_file interface.
141 * @path: Path in procfs
142 * @header: Banner to be printed at the beginning of the file.
143 * @ids: ipc id table to iterate.
144 * @show: show routine.
145 */
146void __init ipc_init_proc_interface(const char *path, const char *header,
147		int ids, int (*show)(struct seq_file *, void *))
148{
149	struct proc_dir_entry *pde;
150	struct ipc_proc_iface *iface;
151
152	iface = kmalloc(sizeof(*iface), GFP_KERNEL);
153	if (!iface)
154		return;
155	iface->path	= path;
156	iface->header	= header;
157	iface->ids	= ids;
158	iface->show	= show;
159
160	pde = proc_create_data(path,
161			       S_IRUGO,        /* world readable */
162			       NULL,           /* parent dir */
163			       &sysvipc_proc_fops,
164			       iface);
165	if (!pde)
166		kfree(iface);
167}
168#endif
169
170/**
171 * ipc_findkey	- find a key in an ipc identifier set
172 * @ids: ipc identifier set
173 * @key: key to find
174 *
175 * Returns the locked pointer to the ipc structure if found or NULL
176 * otherwise. If key is found ipc points to the owning ipc structure
177 *
178 * Called with writer ipc_ids.rwsem held.
179 */
180static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
181{
182	struct kern_ipc_perm *ipcp = NULL;
183
184	if (likely(ids->tables_initialized))
185		ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
186					      ipc_kht_params);
187
188	if (ipcp) {
189		rcu_read_lock();
190		ipc_lock_object(ipcp);
191		return ipcp;
192	}
193
194	return NULL;
195}
196
197#ifdef CONFIG_CHECKPOINT_RESTORE
198/*
199 * Specify desired id for next allocated IPC object.
200 */
201#define ipc_idr_alloc(ids, new)						\
202	idr_alloc(&(ids)->ipcs_idr, (new),				\
203		  (ids)->next_id < 0 ? 0 : ipcid_to_idx((ids)->next_id),\
204		  0, GFP_NOWAIT)
205
206static inline int ipc_buildid(int id, struct ipc_ids *ids,
207			      struct kern_ipc_perm *new)
208{
209	if (ids->next_id < 0) { /* default, behave as !CHECKPOINT_RESTORE */
210		new->seq = ids->seq++;
211		if (ids->seq > IPCID_SEQ_MAX)
212			ids->seq = 0;
213	} else {
214		new->seq = ipcid_to_seqx(ids->next_id);
215		ids->next_id = -1;
216	}
217
218	return SEQ_MULTIPLIER * new->seq + id;
219}
220
221#else
222#define ipc_idr_alloc(ids, new)					\
223	idr_alloc(&(ids)->ipcs_idr, (new), 0, 0, GFP_NOWAIT)
224
225static inline int ipc_buildid(int id, struct ipc_ids *ids,
226			      struct kern_ipc_perm *new)
227{
228	new->seq = ids->seq++;
229	if (ids->seq > IPCID_SEQ_MAX)
230		ids->seq = 0;
231
232	return SEQ_MULTIPLIER * new->seq + id;
233}
234
235#endif /* CONFIG_CHECKPOINT_RESTORE */
236
237/**
238 * ipc_addid - add an ipc identifier
239 * @ids: ipc identifier set
240 * @new: new ipc permission set
241 * @limit: limit for the number of used ids
242 *
243 * Add an entry 'new' to the ipc ids idr. The permissions object is
244 * initialised and the first free entry is set up and the id assigned
245 * is returned. The 'new' entry is returned in a locked state on success.
246 * On failure the entry is not locked and a negative err-code is returned.
247 *
248 * Called with writer ipc_ids.rwsem held.
249 */
250int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
251{
252	kuid_t euid;
253	kgid_t egid;
254	int id, err;
255
256	if (limit > IPCMNI)
257		limit = IPCMNI;
258
259	if (!ids->tables_initialized || ids->in_use >= limit)
260		return -ENOSPC;
261
262	idr_preload(GFP_KERNEL);
263
264	refcount_set(&new->refcount, 1);
265	spin_lock_init(&new->lock);
266	new->deleted = false;
267	rcu_read_lock();
268	spin_lock(&new->lock);
269
270	current_euid_egid(&euid, &egid);
271	new->cuid = new->uid = euid;
272	new->gid = new->cgid = egid;
273
274	id = ipc_idr_alloc(ids, new);
275	idr_preload_end();
276
277	if (id >= 0 && new->key != IPC_PRIVATE) {
278		err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
279					     ipc_kht_params);
280		if (err < 0) {
281			idr_remove(&ids->ipcs_idr, id);
282			id = err;
283		}
284	}
285	if (id < 0) {
286		spin_unlock(&new->lock);
287		rcu_read_unlock();
288		return id;
289	}
290
291	ids->in_use++;
292	if (id > ids->max_id)
293		ids->max_id = id;
294
295	new->id = ipc_buildid(id, ids, new);
296
297	return id;
298}
299
300/**
301 * ipcget_new -	create a new ipc object
302 * @ns: ipc namespace
303 * @ids: ipc identifier set
304 * @ops: the actual creation routine to call
305 * @params: its parameters
306 *
307 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
308 * when the key is IPC_PRIVATE.
309 */
310static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
311		const struct ipc_ops *ops, struct ipc_params *params)
312{
313	int err;
314
315	down_write(&ids->rwsem);
316	err = ops->getnew(ns, params);
317	up_write(&ids->rwsem);
318	return err;
319}
320
321/**
322 * ipc_check_perms - check security and permissions for an ipc object
323 * @ns: ipc namespace
324 * @ipcp: ipc permission set
325 * @ops: the actual security routine to call
326 * @params: its parameters
327 *
328 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
329 * when the key is not IPC_PRIVATE and that key already exists in the
330 * ds IDR.
331 *
332 * On success, the ipc id is returned.
333 *
334 * It is called with ipc_ids.rwsem and ipcp->lock held.
335 */
336static int ipc_check_perms(struct ipc_namespace *ns,
337			   struct kern_ipc_perm *ipcp,
338			   const struct ipc_ops *ops,
339			   struct ipc_params *params)
340{
341	int err;
342
343	if (ipcperms(ns, ipcp, params->flg))
344		err = -EACCES;
345	else {
346		err = ops->associate(ipcp, params->flg);
347		if (!err)
348			err = ipcp->id;
349	}
350
351	return err;
352}
353
354/**
355 * ipcget_public - get an ipc object or create a new one
356 * @ns: ipc namespace
357 * @ids: ipc identifier set
358 * @ops: the actual creation routine to call
359 * @params: its parameters
360 *
361 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
362 * when the key is not IPC_PRIVATE.
363 * It adds a new entry if the key is not found and does some permission
364 * / security checkings if the key is found.
365 *
366 * On success, the ipc id is returned.
367 */
368static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
369		const struct ipc_ops *ops, struct ipc_params *params)
370{
371	struct kern_ipc_perm *ipcp;
372	int flg = params->flg;
373	int err;
374
375	/*
376	 * Take the lock as a writer since we are potentially going to add
377	 * a new entry + read locks are not "upgradable"
378	 */
379	down_write(&ids->rwsem);
380	ipcp = ipc_findkey(ids, params->key);
381	if (ipcp == NULL) {
382		/* key not used */
383		if (!(flg & IPC_CREAT))
384			err = -ENOENT;
385		else
386			err = ops->getnew(ns, params);
387	} else {
388		/* ipc object has been locked by ipc_findkey() */
389
390		if (flg & IPC_CREAT && flg & IPC_EXCL)
391			err = -EEXIST;
392		else {
393			err = 0;
394			if (ops->more_checks)
395				err = ops->more_checks(ipcp, params);
396			if (!err)
397				/*
398				 * ipc_check_perms returns the IPC id on
399				 * success
400				 */
401				err = ipc_check_perms(ns, ipcp, ops, params);
402		}
403		ipc_unlock(ipcp);
404	}
405	up_write(&ids->rwsem);
406
407	return err;
408}
409
410/**
411 * ipc_kht_remove - remove an ipc from the key hashtable
412 * @ids: ipc identifier set
413 * @ipcp: ipc perm structure containing the key to remove
414 *
415 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
416 * before this function is called, and remain locked on the exit.
417 */
418static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
419{
420	if (ipcp->key != IPC_PRIVATE)
421		rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
422				       ipc_kht_params);
423}
424
425/**
426 * ipc_rmid - remove an ipc identifier
427 * @ids: ipc identifier set
428 * @ipcp: ipc perm structure containing the identifier to remove
429 *
430 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
431 * before this function is called, and remain locked on the exit.
432 */
433void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
434{
435	int lid = ipcid_to_idx(ipcp->id);
436
437	idr_remove(&ids->ipcs_idr, lid);
438	ipc_kht_remove(ids, ipcp);
439	ids->in_use--;
440	ipcp->deleted = true;
441
442	if (unlikely(lid == ids->max_id)) {
443		do {
444			lid--;
445			if (lid == -1)
446				break;
447		} while (!idr_find(&ids->ipcs_idr, lid));
448		ids->max_id = lid;
449	}
450}
451
452/**
453 * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
454 * @ids: ipc identifier set
455 * @ipcp: ipc perm structure containing the key to modify
456 *
457 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
458 * before this function is called, and remain locked on the exit.
459 */
460void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
461{
462	ipc_kht_remove(ids, ipcp);
463	ipcp->key = IPC_PRIVATE;
464}
465
466int ipc_rcu_getref(struct kern_ipc_perm *ptr)
467{
468	return refcount_inc_not_zero(&ptr->refcount);
469}
470
471void ipc_rcu_putref(struct kern_ipc_perm *ptr,
472			void (*func)(struct rcu_head *head))
473{
474	if (!refcount_dec_and_test(&ptr->refcount))
475		return;
476
477	call_rcu(&ptr->rcu, func);
478}
479
480/**
481 * ipcperms - check ipc permissions
482 * @ns: ipc namespace
483 * @ipcp: ipc permission set
484 * @flag: desired permission set
485 *
486 * Check user, group, other permissions for access
487 * to ipc resources. return 0 if allowed
488 *
489 * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
490 */
491int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
492{
493	kuid_t euid = current_euid();
494	int requested_mode, granted_mode;
495
496	audit_ipc_obj(ipcp);
497	requested_mode = (flag >> 6) | (flag >> 3) | flag;
498	granted_mode = ipcp->mode;
499	if (uid_eq(euid, ipcp->cuid) ||
500	    uid_eq(euid, ipcp->uid))
501		granted_mode >>= 6;
502	else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
503		granted_mode >>= 3;
504	/* is there some bit set in requested_mode but not in granted_mode? */
505	if ((requested_mode & ~granted_mode & 0007) &&
506	    !ns_capable(ns->user_ns, CAP_IPC_OWNER))
507		return -1;
508
509	return security_ipc_permission(ipcp, flag);
510}
511
512/*
513 * Functions to convert between the kern_ipc_perm structure and the
514 * old/new ipc_perm structures
515 */
516
517/**
518 * kernel_to_ipc64_perm	- convert kernel ipc permissions to user
519 * @in: kernel permissions
520 * @out: new style ipc permissions
521 *
522 * Turn the kernel object @in into a set of permissions descriptions
523 * for returning to userspace (@out).
524 */
525void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
526{
527	out->key	= in->key;
528	out->uid	= from_kuid_munged(current_user_ns(), in->uid);
529	out->gid	= from_kgid_munged(current_user_ns(), in->gid);
530	out->cuid	= from_kuid_munged(current_user_ns(), in->cuid);
531	out->cgid	= from_kgid_munged(current_user_ns(), in->cgid);
532	out->mode	= in->mode;
533	out->seq	= in->seq;
534}
535
536/**
537 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
538 * @in: new style ipc permissions
539 * @out: old style ipc permissions
540 *
541 * Turn the new style permissions object @in into a compatibility
542 * object and store it into the @out pointer.
543 */
544void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
545{
546	out->key	= in->key;
547	SET_UID(out->uid, in->uid);
548	SET_GID(out->gid, in->gid);
549	SET_UID(out->cuid, in->cuid);
550	SET_GID(out->cgid, in->cgid);
551	out->mode	= in->mode;
552	out->seq	= in->seq;
553}
554
555/**
556 * ipc_obtain_object_idr
557 * @ids: ipc identifier set
558 * @id: ipc id to look for
559 *
560 * Look for an id in the ipc ids idr and return associated ipc object.
561 *
562 * Call inside the RCU critical section.
563 * The ipc object is *not* locked on exit.
564 */
565struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
566{
567	struct kern_ipc_perm *out;
568	int lid = ipcid_to_idx(id);
569
570	if (unlikely(!ids->tables_initialized))
571		return ERR_PTR(-EINVAL);
572
573	out = idr_find(&ids->ipcs_idr, lid);
574	if (!out)
575		return ERR_PTR(-EINVAL);
576
577	return out;
578}
579
580/**
581 * ipc_lock - lock an ipc structure without rwsem held
582 * @ids: ipc identifier set
583 * @id: ipc id to look for
584 *
585 * Look for an id in the ipc ids idr and lock the associated ipc object.
586 *
587 * The ipc object is locked on successful exit.
588 */
589struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
590{
591	struct kern_ipc_perm *out;
592
593	rcu_read_lock();
594	out = ipc_obtain_object_idr(ids, id);
595	if (IS_ERR(out))
596		goto err;
597
598	spin_lock(&out->lock);
599
600	/*
601	 * ipc_rmid() may have already freed the ID while ipc_lock()
602	 * was spinning: here verify that the structure is still valid.
603	 * Upon races with RMID, return -EIDRM, thus indicating that
604	 * the ID points to a removed identifier.
605	 */
606	if (ipc_valid_object(out))
607		return out;
608
609	spin_unlock(&out->lock);
610	out = ERR_PTR(-EIDRM);
611err:
612	rcu_read_unlock();
613	return out;
614}
615
616/**
617 * ipc_obtain_object_check
618 * @ids: ipc identifier set
619 * @id: ipc id to look for
620 *
621 * Similar to ipc_obtain_object_idr() but also checks
622 * the ipc object reference counter.
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_check(struct ipc_ids *ids, int id)
628{
629	struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
630
631	if (IS_ERR(out))
632		goto out;
633
634	if (ipc_checkid(out, id))
635		return ERR_PTR(-EINVAL);
636out:
637	return out;
638}
639
640/**
641 * ipcget - Common sys_*get() code
642 * @ns: namespace
643 * @ids: ipc identifier set
644 * @ops: operations to be called on ipc object creation, permission checks
645 *       and further checks
646 * @params: the parameters needed by the previous operations.
647 *
648 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
649 */
650int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
651			const struct ipc_ops *ops, struct ipc_params *params)
652{
653	if (params->key == IPC_PRIVATE)
654		return ipcget_new(ns, ids, ops, params);
655	else
656		return ipcget_public(ns, ids, ops, params);
657}
658
659/**
660 * ipc_update_perm - update the permissions of an ipc object
661 * @in:  the permission given as input.
662 * @out: the permission of the ipc to set.
663 */
664int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
665{
666	kuid_t uid = make_kuid(current_user_ns(), in->uid);
667	kgid_t gid = make_kgid(current_user_ns(), in->gid);
668	if (!uid_valid(uid) || !gid_valid(gid))
669		return -EINVAL;
670
671	out->uid = uid;
672	out->gid = gid;
673	out->mode = (out->mode & ~S_IRWXUGO)
674		| (in->mode & S_IRWXUGO);
675
676	return 0;
677}
678
679/**
680 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
681 * @ns:  ipc namespace
682 * @ids:  the table of ids where to look for the ipc
683 * @id:   the id of the ipc to retrieve
684 * @cmd:  the cmd to check
685 * @perm: the permission to set
686 * @extra_perm: one extra permission parameter used by msq
687 *
688 * This function does some common audit and permissions check for some IPC_XXX
689 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
690 * It must be called without any lock held and:
691 *
692 *   - retrieves the ipc with the given id in the given table.
693 *   - performs some audit and permission check, depending on the given cmd
694 *   - returns a pointer to the ipc object or otherwise, the corresponding
695 *     error.
696 *
697 * Call holding the both the rwsem and the rcu read lock.
698 */
699struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
700					struct ipc_ids *ids, int id, int cmd,
701					struct ipc64_perm *perm, int extra_perm)
702{
703	kuid_t euid;
704	int err = -EPERM;
705	struct kern_ipc_perm *ipcp;
706
707	ipcp = ipc_obtain_object_check(ids, id);
708	if (IS_ERR(ipcp)) {
709		err = PTR_ERR(ipcp);
710		goto err;
711	}
712
713	audit_ipc_obj(ipcp);
714	if (cmd == IPC_SET)
715		audit_ipc_set_perm(extra_perm, perm->uid,
716				   perm->gid, perm->mode);
717
718	euid = current_euid();
719	if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
720	    ns_capable(ns->user_ns, CAP_SYS_ADMIN))
721		return ipcp; /* successful lookup */
722err:
723	return ERR_PTR(err);
724}
725
726#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
727
728
729/**
730 * ipc_parse_version - ipc call version
731 * @cmd: pointer to command
732 *
733 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
734 * The @cmd value is turned from an encoding command and version into
735 * just the command code.
736 */
737int ipc_parse_version(int *cmd)
738{
739	if (*cmd & IPC_64) {
740		*cmd ^= IPC_64;
741		return IPC_64;
742	} else {
743		return IPC_OLD;
744	}
745}
746
747#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
748
749#ifdef CONFIG_PROC_FS
750struct ipc_proc_iter {
751	struct ipc_namespace *ns;
752	struct pid_namespace *pid_ns;
753	struct ipc_proc_iface *iface;
754};
755
756struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
757{
758	struct ipc_proc_iter *iter = s->private;
759	return iter->pid_ns;
760}
761
762/*
763 * This routine locks the ipc structure found at least at position pos.
764 */
765static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
766					      loff_t *new_pos)
767{
768	struct kern_ipc_perm *ipc;
769	int total, id;
770
771	total = 0;
772	for (id = 0; id < pos && total < ids->in_use; id++) {
773		ipc = idr_find(&ids->ipcs_idr, id);
774		if (ipc != NULL)
775			total++;
776	}
777
778	if (total >= ids->in_use)
779		return NULL;
780
781	for (; pos < IPCMNI; pos++) {
782		ipc = idr_find(&ids->ipcs_idr, pos);
783		if (ipc != NULL) {
784			*new_pos = pos + 1;
785			rcu_read_lock();
786			ipc_lock_object(ipc);
787			return ipc;
788		}
789	}
790
791	/* Out of range - return NULL to terminate iteration */
792	return NULL;
793}
794
795static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
796{
797	struct ipc_proc_iter *iter = s->private;
798	struct ipc_proc_iface *iface = iter->iface;
799	struct kern_ipc_perm *ipc = it;
800
801	/* If we had an ipc id locked before, unlock it */
802	if (ipc && ipc != SEQ_START_TOKEN)
803		ipc_unlock(ipc);
804
805	return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
806}
807
808/*
809 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
810 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
811 */
812static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
813{
814	struct ipc_proc_iter *iter = s->private;
815	struct ipc_proc_iface *iface = iter->iface;
816	struct ipc_ids *ids;
817
818	ids = &iter->ns->ids[iface->ids];
819
820	/*
821	 * Take the lock - this will be released by the corresponding
822	 * call to stop().
823	 */
824	down_read(&ids->rwsem);
825
826	/* pos < 0 is invalid */
827	if (*pos < 0)
828		return NULL;
829
830	/* pos == 0 means header */
831	if (*pos == 0)
832		return SEQ_START_TOKEN;
833
834	/* Find the (pos-1)th ipc */
835	return sysvipc_find_ipc(ids, *pos - 1, pos);
836}
837
838static void sysvipc_proc_stop(struct seq_file *s, void *it)
839{
840	struct kern_ipc_perm *ipc = it;
841	struct ipc_proc_iter *iter = s->private;
842	struct ipc_proc_iface *iface = iter->iface;
843	struct ipc_ids *ids;
844
845	/* If we had a locked structure, release it */
846	if (ipc && ipc != SEQ_START_TOKEN)
847		ipc_unlock(ipc);
848
849	ids = &iter->ns->ids[iface->ids];
850	/* Release the lock we took in start() */
851	up_read(&ids->rwsem);
852}
853
854static int sysvipc_proc_show(struct seq_file *s, void *it)
855{
856	struct ipc_proc_iter *iter = s->private;
857	struct ipc_proc_iface *iface = iter->iface;
858
859	if (it == SEQ_START_TOKEN) {
860		seq_puts(s, iface->header);
861		return 0;
862	}
863
864	return iface->show(s, it);
865}
866
867static const struct seq_operations sysvipc_proc_seqops = {
868	.start = sysvipc_proc_start,
869	.stop  = sysvipc_proc_stop,
870	.next  = sysvipc_proc_next,
871	.show  = sysvipc_proc_show,
872};
873
874static int sysvipc_proc_open(struct inode *inode, struct file *file)
875{
876	struct ipc_proc_iter *iter;
877
878	iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
879	if (!iter)
880		return -ENOMEM;
881
882	iter->iface = PDE_DATA(inode);
883	iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
884	iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
885
886	return 0;
887}
888
889static int sysvipc_proc_release(struct inode *inode, struct file *file)
890{
891	struct seq_file *seq = file->private_data;
892	struct ipc_proc_iter *iter = seq->private;
893	put_ipc_ns(iter->ns);
894	put_pid_ns(iter->pid_ns);
895	return seq_release_private(inode, file);
896}
897
898static const struct file_operations sysvipc_proc_fops = {
899	.open    = sysvipc_proc_open,
900	.read    = seq_read,
901	.llseek  = seq_lseek,
902	.release = sysvipc_proc_release,
903};
904#endif /* CONFIG_PROC_FS */
905