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