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
73 struct 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 */
ipc_init(void)90 static 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 }
99 device_initcall(ipc_init);
100
101 static 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 */
ipc_init_ids(struct ipc_ids * ids)115 void 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
130 static 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 */
ipc_init_proc_interface(const char * path,const char * header,int ids,int (* show)(struct seq_file *,void *))138 void __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 */
ipc_findkey(struct ipc_ids * ids,key_t key)172 static 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 */
ipc_idr_alloc(struct ipc_ids * ids,struct kern_ipc_perm * new)202 static 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 */
ipc_addid(struct ipc_ids * ids,struct kern_ipc_perm * new,int limit)278 int 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 */
ipcget_new(struct ipc_namespace * ns,struct ipc_ids * ids,const struct ipc_ops * ops,struct ipc_params * params)339 static 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 */
ipc_check_perms(struct ipc_namespace * ns,struct kern_ipc_perm * ipcp,const struct ipc_ops * ops,struct ipc_params * params)365 static 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 */
ipcget_public(struct ipc_namespace * ns,struct ipc_ids * ids,const struct ipc_ops * ops,struct ipc_params * params)397 static 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 */
ipc_kht_remove(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)447 static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
448 {
449 if (ipcp->key != IPC_PRIVATE)
450 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 */
ipc_search_maxidx(struct ipc_ids * ids,int limit)467 static 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 */
ipc_rmid(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)497 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
498 {
499 int idx = ipcid_to_idx(ipcp->id);
500
501 idr_remove(&ids->ipcs_idr, idx);
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 */
ipc_set_key_private(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)522 void 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
ipc_rcu_getref(struct kern_ipc_perm * ptr)528 bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
529 {
530 return refcount_inc_not_zero(&ptr->refcount);
531 }
532
ipc_rcu_putref(struct kern_ipc_perm * ptr,void (* func)(struct rcu_head * head))533 void 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 */
ipcperms(struct ipc_namespace * ns,struct kern_ipc_perm * ipcp,short flag)553 int 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 */
kernel_to_ipc64_perm(struct kern_ipc_perm * in,struct ipc64_perm * out)587 void 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 */
ipc64_perm_to_ipc_perm(struct ipc64_perm * in,struct ipc_perm * out)606 void 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 */
ipc_obtain_object_idr(struct ipc_ids * ids,int id)627 struct 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 */
ipc_obtain_object_check(struct ipc_ids * ids,int id)650 struct 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);
659 out:
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 */
ipcget(struct ipc_namespace * ns,struct ipc_ids * ids,const struct ipc_ops * ops,struct ipc_params * params)673 int 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 */
ipc_update_perm(struct ipc64_perm * in,struct kern_ipc_perm * out)687 int 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 */
ipcctl_obtain_check(struct ipc_namespace * ns,struct ipc_ids * ids,int id,int cmd,struct ipc64_perm * perm,int extra_perm)722 struct 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 */
745 err:
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 */
ipc_parse_version(int * cmd)760 int 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
773 struct ipc_proc_iter {
774 struct ipc_namespace *ns;
775 struct pid_namespace *pid_ns;
776 struct ipc_proc_iface *iface;
777 };
778
ipc_seq_pid_ns(struct seq_file * s)779 struct 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 * This routine locks the ipc structure found at least at position pos.
787 */
sysvipc_find_ipc(struct ipc_ids * ids,loff_t pos,loff_t * new_pos)788 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
789 loff_t *new_pos)
790 {
791 struct kern_ipc_perm *ipc = NULL;
792 int max_idx = ipc_get_maxidx(ids);
793
794 if (max_idx == -1 || pos > max_idx)
795 goto out;
796
797 for (; pos <= max_idx; pos++) {
798 ipc = idr_find(&ids->ipcs_idr, pos);
799 if (ipc != NULL) {
800 rcu_read_lock();
801 ipc_lock_object(ipc);
802 break;
803 }
804 }
805 out:
806 *new_pos = pos + 1;
807 return ipc;
808 }
809
sysvipc_proc_next(struct seq_file * s,void * it,loff_t * pos)810 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
811 {
812 struct ipc_proc_iter *iter = s->private;
813 struct ipc_proc_iface *iface = iter->iface;
814 struct kern_ipc_perm *ipc = it;
815
816 /* If we had an ipc id locked before, unlock it */
817 if (ipc && ipc != SEQ_START_TOKEN)
818 ipc_unlock(ipc);
819
820 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
821 }
822
823 /*
824 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
825 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
826 */
sysvipc_proc_start(struct seq_file * s,loff_t * pos)827 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
828 {
829 struct ipc_proc_iter *iter = s->private;
830 struct ipc_proc_iface *iface = iter->iface;
831 struct ipc_ids *ids;
832
833 ids = &iter->ns->ids[iface->ids];
834
835 /*
836 * Take the lock - this will be released by the corresponding
837 * call to stop().
838 */
839 down_read(&ids->rwsem);
840
841 /* pos < 0 is invalid */
842 if (*pos < 0)
843 return NULL;
844
845 /* pos == 0 means header */
846 if (*pos == 0)
847 return SEQ_START_TOKEN;
848
849 /* Find the (pos-1)th ipc */
850 return sysvipc_find_ipc(ids, *pos - 1, pos);
851 }
852
sysvipc_proc_stop(struct seq_file * s,void * it)853 static void sysvipc_proc_stop(struct seq_file *s, void *it)
854 {
855 struct kern_ipc_perm *ipc = it;
856 struct ipc_proc_iter *iter = s->private;
857 struct ipc_proc_iface *iface = iter->iface;
858 struct ipc_ids *ids;
859
860 /* If we had a locked structure, release it */
861 if (ipc && ipc != SEQ_START_TOKEN)
862 ipc_unlock(ipc);
863
864 ids = &iter->ns->ids[iface->ids];
865 /* Release the lock we took in start() */
866 up_read(&ids->rwsem);
867 }
868
sysvipc_proc_show(struct seq_file * s,void * it)869 static int sysvipc_proc_show(struct seq_file *s, void *it)
870 {
871 struct ipc_proc_iter *iter = s->private;
872 struct ipc_proc_iface *iface = iter->iface;
873
874 if (it == SEQ_START_TOKEN) {
875 seq_puts(s, iface->header);
876 return 0;
877 }
878
879 return iface->show(s, it);
880 }
881
882 static const struct seq_operations sysvipc_proc_seqops = {
883 .start = sysvipc_proc_start,
884 .stop = sysvipc_proc_stop,
885 .next = sysvipc_proc_next,
886 .show = sysvipc_proc_show,
887 };
888
sysvipc_proc_open(struct inode * inode,struct file * file)889 static int sysvipc_proc_open(struct inode *inode, struct file *file)
890 {
891 struct ipc_proc_iter *iter;
892
893 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
894 if (!iter)
895 return -ENOMEM;
896
897 iter->iface = PDE_DATA(inode);
898 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
899 iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
900
901 return 0;
902 }
903
sysvipc_proc_release(struct inode * inode,struct file * file)904 static int sysvipc_proc_release(struct inode *inode, struct file *file)
905 {
906 struct seq_file *seq = file->private_data;
907 struct ipc_proc_iter *iter = seq->private;
908 put_ipc_ns(iter->ns);
909 put_pid_ns(iter->pid_ns);
910 return seq_release_private(inode, file);
911 }
912
913 static const struct proc_ops sysvipc_proc_ops = {
914 .proc_flags = PROC_ENTRY_PERMANENT,
915 .proc_open = sysvipc_proc_open,
916 .proc_read = seq_read,
917 .proc_lseek = seq_lseek,
918 .proc_release = sysvipc_proc_release,
919 };
920 #endif /* CONFIG_PROC_FS */
921
