Line data Source code
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 :
72 : struct 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 : */
89 1 : static int __init ipc_init(void)
90 : {
91 1 : proc_mkdir("sysvipc", NULL);
92 1 : sem_init();
93 1 : msg_init();
94 1 : shm_init();
95 :
96 1 : return 0;
97 : }
98 : device_initcall(ipc_init);
99 :
100 : static const struct rhashtable_params ipc_kht_params = {
101 : .head_offset = offsetof(struct kern_ipc_perm, khtnode),
102 : .key_offset = offsetof(struct kern_ipc_perm, key),
103 : .key_len = sizeof_field(struct kern_ipc_perm, key),
104 : .automatic_shrinking = true,
105 : };
106 :
107 : /**
108 : * ipc_init_ids - initialise ipc identifiers
109 : * @ids: ipc identifier set
110 : *
111 : * Set up the sequence range to use for the ipc identifier range (limited
112 : * below ipc_mni) then initialise the keys hashtable and ids idr.
113 : */
114 3 : void ipc_init_ids(struct ipc_ids *ids)
115 : {
116 3 : ids->in_use = 0;
117 3 : ids->seq = 0;
118 3 : init_rwsem(&ids->rwsem);
119 3 : rhashtable_init(&ids->key_ht, &ipc_kht_params);
120 3 : idr_init(&ids->ipcs_idr);
121 3 : ids->max_idx = -1;
122 3 : ids->last_idx = -1;
123 : #ifdef CONFIG_CHECKPOINT_RESTORE
124 : ids->next_id = -1;
125 : #endif
126 3 : }
127 :
128 : #ifdef CONFIG_PROC_FS
129 : static const struct proc_ops sysvipc_proc_ops;
130 : /**
131 : * ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
132 : * @path: Path in procfs
133 : * @header: Banner to be printed at the beginning of the file.
134 : * @ids: ipc id table to iterate.
135 : * @show: show routine.
136 : */
137 3 : void __init ipc_init_proc_interface(const char *path, const char *header,
138 : int ids, int (*show)(struct seq_file *, void *))
139 : {
140 3 : struct proc_dir_entry *pde;
141 3 : struct ipc_proc_iface *iface;
142 :
143 3 : iface = kmalloc(sizeof(*iface), GFP_KERNEL);
144 3 : if (!iface)
145 : return;
146 3 : iface->path = path;
147 3 : iface->header = header;
148 3 : iface->ids = ids;
149 3 : iface->show = show;
150 :
151 3 : pde = proc_create_data(path,
152 : S_IRUGO, /* world readable */
153 : NULL, /* parent dir */
154 : &sysvipc_proc_ops,
155 : iface);
156 3 : if (!pde)
157 0 : kfree(iface);
158 : }
159 : #endif
160 :
161 : /**
162 : * ipc_findkey - find a key in an ipc identifier set
163 : * @ids: ipc identifier set
164 : * @key: key to find
165 : *
166 : * Returns the locked pointer to the ipc structure if found or NULL
167 : * otherwise. If key is found ipc points to the owning ipc structure
168 : *
169 : * Called with writer ipc_ids.rwsem held.
170 : */
171 0 : static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
172 : {
173 0 : struct kern_ipc_perm *ipcp;
174 :
175 0 : ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
176 : ipc_kht_params);
177 0 : if (!ipcp)
178 : return NULL;
179 :
180 0 : rcu_read_lock();
181 0 : ipc_lock_object(ipcp);
182 0 : return ipcp;
183 : }
184 :
185 : /*
186 : * Insert new IPC object into idr tree, and set sequence number and id
187 : * in the correct order.
188 : * Especially:
189 : * - the sequence number must be set before inserting the object into the idr,
190 : * because the sequence number is accessed without a lock.
191 : * - the id can/must be set after inserting the object into the idr.
192 : * All accesses must be done after getting kern_ipc_perm.lock.
193 : *
194 : * The caller must own kern_ipc_perm.lock.of the new object.
195 : * On error, the function returns a (negative) error code.
196 : *
197 : * To conserve sequence number space, especially with extended ipc_mni,
198 : * the sequence number is incremented only when the returned ID is less than
199 : * the last one.
200 : */
201 0 : static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
202 : {
203 0 : int idx, next_id = -1;
204 :
205 : #ifdef CONFIG_CHECKPOINT_RESTORE
206 : next_id = ids->next_id;
207 : ids->next_id = -1;
208 : #endif
209 :
210 : /*
211 : * As soon as a new object is inserted into the idr,
212 : * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
213 : * and the lockless preparations for ipc operations can start.
214 : * This means especially: permission checks, audit calls, allocation
215 : * of undo structures, ...
216 : *
217 : * Thus the object must be fully initialized, and if something fails,
218 : * then the full tear-down sequence must be followed.
219 : * (i.e.: set new->deleted, reduce refcount, call_rcu())
220 : */
221 :
222 0 : if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
223 0 : int max_idx;
224 :
225 0 : max_idx = max(ids->in_use*3/2, ipc_min_cycle);
226 0 : max_idx = min(max_idx, ipc_mni);
227 :
228 : /* allocate the idx, with a NULL struct kern_ipc_perm */
229 0 : idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
230 : GFP_NOWAIT);
231 :
232 0 : if (idx >= 0) {
233 : /*
234 : * idx got allocated successfully.
235 : * Now calculate the sequence number and set the
236 : * pointer for real.
237 : */
238 0 : if (idx <= ids->last_idx) {
239 0 : ids->seq++;
240 0 : if (ids->seq >= ipcid_seq_max())
241 0 : ids->seq = 0;
242 : }
243 0 : ids->last_idx = idx;
244 :
245 0 : new->seq = ids->seq;
246 : /* no need for smp_wmb(), this is done
247 : * inside idr_replace, as part of
248 : * rcu_assign_pointer
249 : */
250 0 : idr_replace(&ids->ipcs_idr, new, idx);
251 : }
252 : } else {
253 : new->seq = ipcid_to_seqx(next_id);
254 : idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
255 : 0, GFP_NOWAIT);
256 : }
257 0 : if (idx >= 0)
258 0 : new->id = (new->seq << ipcmni_seq_shift()) + idx;
259 0 : return idx;
260 : }
261 :
262 : /**
263 : * ipc_addid - add an ipc identifier
264 : * @ids: ipc identifier set
265 : * @new: new ipc permission set
266 : * @limit: limit for the number of used ids
267 : *
268 : * Add an entry 'new' to the ipc ids idr. The permissions object is
269 : * initialised and the first free entry is set up and the index assigned
270 : * is returned. The 'new' entry is returned in a locked state on success.
271 : *
272 : * On failure the entry is not locked and a negative err-code is returned.
273 : * The caller must use ipc_rcu_putref() to free the identifier.
274 : *
275 : * Called with writer ipc_ids.rwsem held.
276 : */
277 0 : int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
278 : {
279 0 : kuid_t euid;
280 0 : kgid_t egid;
281 0 : int idx, err;
282 :
283 : /* 1) Initialize the refcount so that ipc_rcu_putref works */
284 0 : refcount_set(&new->refcount, 1);
285 :
286 0 : if (limit > ipc_mni)
287 : limit = ipc_mni;
288 :
289 0 : if (ids->in_use >= limit)
290 : return -ENOSPC;
291 :
292 0 : idr_preload(GFP_KERNEL);
293 :
294 0 : spin_lock_init(&new->lock);
295 0 : rcu_read_lock();
296 0 : spin_lock(&new->lock);
297 :
298 0 : current_euid_egid(&euid, &egid);
299 0 : new->cuid = new->uid = euid;
300 0 : new->gid = new->cgid = egid;
301 :
302 0 : new->deleted = false;
303 :
304 0 : idx = ipc_idr_alloc(ids, new);
305 0 : idr_preload_end();
306 :
307 0 : if (idx >= 0 && new->key != IPC_PRIVATE) {
308 0 : err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
309 : ipc_kht_params);
310 0 : if (err < 0) {
311 0 : idr_remove(&ids->ipcs_idr, idx);
312 0 : idx = err;
313 : }
314 : }
315 0 : if (idx < 0) {
316 0 : new->deleted = true;
317 0 : spin_unlock(&new->lock);
318 0 : rcu_read_unlock();
319 0 : return idx;
320 : }
321 :
322 0 : ids->in_use++;
323 0 : if (idx > ids->max_idx)
324 0 : ids->max_idx = idx;
325 : return idx;
326 : }
327 :
328 : /**
329 : * ipcget_new - create a new ipc object
330 : * @ns: ipc namespace
331 : * @ids: ipc identifier set
332 : * @ops: the actual creation routine to call
333 : * @params: its parameters
334 : *
335 : * This routine is called by sys_msgget, sys_semget() and sys_shmget()
336 : * when the key is IPC_PRIVATE.
337 : */
338 0 : static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
339 : const struct ipc_ops *ops, struct ipc_params *params)
340 : {
341 0 : int err;
342 :
343 0 : down_write(&ids->rwsem);
344 0 : err = ops->getnew(ns, params);
345 0 : up_write(&ids->rwsem);
346 0 : return err;
347 : }
348 :
349 : /**
350 : * ipc_check_perms - check security and permissions for an ipc object
351 : * @ns: ipc namespace
352 : * @ipcp: ipc permission set
353 : * @ops: the actual security routine to call
354 : * @params: its parameters
355 : *
356 : * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
357 : * when the key is not IPC_PRIVATE and that key already exists in the
358 : * ds IDR.
359 : *
360 : * On success, the ipc id is returned.
361 : *
362 : * It is called with ipc_ids.rwsem and ipcp->lock held.
363 : */
364 0 : static int ipc_check_perms(struct ipc_namespace *ns,
365 : struct kern_ipc_perm *ipcp,
366 : const struct ipc_ops *ops,
367 : struct ipc_params *params)
368 : {
369 0 : int err;
370 :
371 0 : if (ipcperms(ns, ipcp, params->flg))
372 : err = -EACCES;
373 : else {
374 0 : err = ops->associate(ipcp, params->flg);
375 0 : if (!err)
376 0 : err = ipcp->id;
377 : }
378 :
379 0 : return err;
380 : }
381 :
382 : /**
383 : * ipcget_public - get an ipc object or create a new one
384 : * @ns: ipc namespace
385 : * @ids: ipc identifier set
386 : * @ops: the actual creation routine to call
387 : * @params: its parameters
388 : *
389 : * This routine is called by sys_msgget, sys_semget() and sys_shmget()
390 : * when the key is not IPC_PRIVATE.
391 : * It adds a new entry if the key is not found and does some permission
392 : * / security checkings if the key is found.
393 : *
394 : * On success, the ipc id is returned.
395 : */
396 0 : static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
397 : const struct ipc_ops *ops, struct ipc_params *params)
398 : {
399 0 : struct kern_ipc_perm *ipcp;
400 0 : int flg = params->flg;
401 0 : int err;
402 :
403 : /*
404 : * Take the lock as a writer since we are potentially going to add
405 : * a new entry + read locks are not "upgradable"
406 : */
407 0 : down_write(&ids->rwsem);
408 0 : ipcp = ipc_findkey(ids, params->key);
409 0 : if (ipcp == NULL) {
410 : /* key not used */
411 0 : if (!(flg & IPC_CREAT))
412 : err = -ENOENT;
413 : else
414 0 : err = ops->getnew(ns, params);
415 : } else {
416 : /* ipc object has been locked by ipc_findkey() */
417 :
418 0 : if (flg & IPC_CREAT && flg & IPC_EXCL)
419 : err = -EEXIST;
420 : else {
421 0 : err = 0;
422 0 : if (ops->more_checks)
423 0 : err = ops->more_checks(ipcp, params);
424 0 : if (!err)
425 : /*
426 : * ipc_check_perms returns the IPC id on
427 : * success
428 : */
429 0 : err = ipc_check_perms(ns, ipcp, ops, params);
430 : }
431 0 : ipc_unlock(ipcp);
432 : }
433 0 : up_write(&ids->rwsem);
434 :
435 0 : return err;
436 : }
437 :
438 : /**
439 : * ipc_kht_remove - remove an ipc from the key hashtable
440 : * @ids: ipc identifier set
441 : * @ipcp: ipc perm structure containing the key to remove
442 : *
443 : * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
444 : * before this function is called, and remain locked on the exit.
445 : */
446 0 : static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
447 : {
448 0 : if (ipcp->key != IPC_PRIVATE)
449 0 : rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
450 : ipc_kht_params);
451 0 : }
452 :
453 : /**
454 : * ipc_rmid - remove an ipc identifier
455 : * @ids: ipc identifier set
456 : * @ipcp: ipc perm structure containing the identifier to remove
457 : *
458 : * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
459 : * before this function is called, and remain locked on the exit.
460 : */
461 0 : void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
462 : {
463 0 : int idx = ipcid_to_idx(ipcp->id);
464 :
465 0 : idr_remove(&ids->ipcs_idr, idx);
466 0 : ipc_kht_remove(ids, ipcp);
467 0 : ids->in_use--;
468 0 : ipcp->deleted = true;
469 :
470 0 : if (unlikely(idx == ids->max_idx)) {
471 0 : do {
472 0 : idx--;
473 0 : if (idx == -1)
474 : break;
475 0 : } while (!idr_find(&ids->ipcs_idr, idx));
476 0 : ids->max_idx = idx;
477 : }
478 0 : }
479 :
480 : /**
481 : * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
482 : * @ids: ipc identifier set
483 : * @ipcp: ipc perm structure containing the key to modify
484 : *
485 : * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
486 : * before this function is called, and remain locked on the exit.
487 : */
488 0 : void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
489 : {
490 0 : ipc_kht_remove(ids, ipcp);
491 0 : ipcp->key = IPC_PRIVATE;
492 0 : }
493 :
494 0 : bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
495 : {
496 0 : return refcount_inc_not_zero(&ptr->refcount);
497 : }
498 :
499 0 : void ipc_rcu_putref(struct kern_ipc_perm *ptr,
500 : void (*func)(struct rcu_head *head))
501 : {
502 0 : if (!refcount_dec_and_test(&ptr->refcount))
503 : return;
504 :
505 0 : call_rcu(&ptr->rcu, func);
506 : }
507 :
508 : /**
509 : * ipcperms - check ipc permissions
510 : * @ns: ipc namespace
511 : * @ipcp: ipc permission set
512 : * @flag: desired permission set
513 : *
514 : * Check user, group, other permissions for access
515 : * to ipc resources. return 0 if allowed
516 : *
517 : * @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
518 : */
519 0 : int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
520 : {
521 0 : kuid_t euid = current_euid();
522 0 : int requested_mode, granted_mode;
523 :
524 0 : audit_ipc_obj(ipcp);
525 0 : requested_mode = (flag >> 6) | (flag >> 3) | flag;
526 0 : granted_mode = ipcp->mode;
527 0 : if (uid_eq(euid, ipcp->cuid) ||
528 0 : uid_eq(euid, ipcp->uid))
529 0 : granted_mode >>= 6;
530 0 : else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
531 0 : granted_mode >>= 3;
532 : /* is there some bit set in requested_mode but not in granted_mode? */
533 0 : if ((requested_mode & ~granted_mode & 0007) &&
534 0 : !ns_capable(ns->user_ns, CAP_IPC_OWNER))
535 : return -1;
536 :
537 0 : return security_ipc_permission(ipcp, flag);
538 : }
539 :
540 : /*
541 : * Functions to convert between the kern_ipc_perm structure and the
542 : * old/new ipc_perm structures
543 : */
544 :
545 : /**
546 : * kernel_to_ipc64_perm - convert kernel ipc permissions to user
547 : * @in: kernel permissions
548 : * @out: new style ipc permissions
549 : *
550 : * Turn the kernel object @in into a set of permissions descriptions
551 : * for returning to userspace (@out).
552 : */
553 0 : void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
554 : {
555 0 : out->key = in->key;
556 0 : out->uid = from_kuid_munged(current_user_ns(), in->uid);
557 0 : out->gid = from_kgid_munged(current_user_ns(), in->gid);
558 0 : out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
559 0 : out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
560 0 : out->mode = in->mode;
561 0 : out->seq = in->seq;
562 0 : }
563 :
564 : /**
565 : * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
566 : * @in: new style ipc permissions
567 : * @out: old style ipc permissions
568 : *
569 : * Turn the new style permissions object @in into a compatibility
570 : * object and store it into the @out pointer.
571 : */
572 0 : void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
573 : {
574 0 : out->key = in->key;
575 0 : SET_UID(out->uid, in->uid);
576 0 : SET_GID(out->gid, in->gid);
577 0 : SET_UID(out->cuid, in->cuid);
578 0 : SET_GID(out->cgid, in->cgid);
579 0 : out->mode = in->mode;
580 0 : out->seq = in->seq;
581 0 : }
582 :
583 : /**
584 : * ipc_obtain_object_idr
585 : * @ids: ipc identifier set
586 : * @id: ipc id to look for
587 : *
588 : * Look for an id in the ipc ids idr and return associated ipc object.
589 : *
590 : * Call inside the RCU critical section.
591 : * The ipc object is *not* locked on exit.
592 : */
593 0 : struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
594 : {
595 0 : struct kern_ipc_perm *out;
596 0 : int idx = ipcid_to_idx(id);
597 :
598 0 : out = idr_find(&ids->ipcs_idr, idx);
599 0 : if (!out)
600 0 : return ERR_PTR(-EINVAL);
601 :
602 : return out;
603 : }
604 :
605 : /**
606 : * ipc_obtain_object_check
607 : * @ids: ipc identifier set
608 : * @id: ipc id to look for
609 : *
610 : * Similar to ipc_obtain_object_idr() but also checks the ipc object
611 : * sequence number.
612 : *
613 : * Call inside the RCU critical section.
614 : * The ipc object is *not* locked on exit.
615 : */
616 0 : struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
617 : {
618 0 : struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
619 :
620 0 : if (IS_ERR(out))
621 0 : goto out;
622 :
623 0 : if (ipc_checkid(out, id))
624 0 : return ERR_PTR(-EINVAL);
625 0 : out:
626 : return out;
627 : }
628 :
629 : /**
630 : * ipcget - Common sys_*get() code
631 : * @ns: namespace
632 : * @ids: ipc identifier set
633 : * @ops: operations to be called on ipc object creation, permission checks
634 : * and further checks
635 : * @params: the parameters needed by the previous operations.
636 : *
637 : * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
638 : */
639 0 : int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
640 : const struct ipc_ops *ops, struct ipc_params *params)
641 : {
642 0 : if (params->key == IPC_PRIVATE)
643 0 : return ipcget_new(ns, ids, ops, params);
644 : else
645 0 : return ipcget_public(ns, ids, ops, params);
646 : }
647 :
648 : /**
649 : * ipc_update_perm - update the permissions of an ipc object
650 : * @in: the permission given as input.
651 : * @out: the permission of the ipc to set.
652 : */
653 0 : int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
654 : {
655 0 : kuid_t uid = make_kuid(current_user_ns(), in->uid);
656 0 : kgid_t gid = make_kgid(current_user_ns(), in->gid);
657 0 : if (!uid_valid(uid) || !gid_valid(gid))
658 : return -EINVAL;
659 :
660 0 : out->uid = uid;
661 0 : out->gid = gid;
662 0 : out->mode = (out->mode & ~S_IRWXUGO)
663 0 : | (in->mode & S_IRWXUGO);
664 :
665 0 : return 0;
666 : }
667 :
668 : /**
669 : * ipcctl_obtain_check - retrieve an ipc object and check permissions
670 : * @ns: ipc namespace
671 : * @ids: the table of ids where to look for the ipc
672 : * @id: the id of the ipc to retrieve
673 : * @cmd: the cmd to check
674 : * @perm: the permission to set
675 : * @extra_perm: one extra permission parameter used by msq
676 : *
677 : * This function does some common audit and permissions check for some IPC_XXX
678 : * cmd and is called from semctl_down, shmctl_down and msgctl_down.
679 : *
680 : * It:
681 : * - retrieves the ipc object with the given id in the given table.
682 : * - performs some audit and permission check, depending on the given cmd
683 : * - returns a pointer to the ipc object or otherwise, the corresponding
684 : * error.
685 : *
686 : * Call holding the both the rwsem and the rcu read lock.
687 : */
688 0 : struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
689 : struct ipc_ids *ids, int id, int cmd,
690 : struct ipc64_perm *perm, int extra_perm)
691 : {
692 0 : kuid_t euid;
693 0 : int err = -EPERM;
694 0 : struct kern_ipc_perm *ipcp;
695 :
696 0 : ipcp = ipc_obtain_object_check(ids, id);
697 0 : if (IS_ERR(ipcp)) {
698 0 : err = PTR_ERR(ipcp);
699 0 : goto err;
700 : }
701 :
702 0 : audit_ipc_obj(ipcp);
703 0 : if (cmd == IPC_SET)
704 0 : audit_ipc_set_perm(extra_perm, perm->uid,
705 : perm->gid, perm->mode);
706 :
707 0 : euid = current_euid();
708 0 : if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
709 0 : ns_capable(ns->user_ns, CAP_SYS_ADMIN))
710 0 : return ipcp; /* successful lookup */
711 0 : err:
712 0 : return ERR_PTR(err);
713 : }
714 :
715 : #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
716 :
717 :
718 : /**
719 : * ipc_parse_version - ipc call version
720 : * @cmd: pointer to command
721 : *
722 : * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
723 : * The @cmd value is turned from an encoding command and version into
724 : * just the command code.
725 : */
726 : int ipc_parse_version(int *cmd)
727 : {
728 : if (*cmd & IPC_64) {
729 : *cmd ^= IPC_64;
730 : return IPC_64;
731 : } else {
732 : return IPC_OLD;
733 : }
734 : }
735 :
736 : #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
737 :
738 : #ifdef CONFIG_PROC_FS
739 : struct ipc_proc_iter {
740 : struct ipc_namespace *ns;
741 : struct pid_namespace *pid_ns;
742 : struct ipc_proc_iface *iface;
743 : };
744 :
745 0 : struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
746 : {
747 0 : struct ipc_proc_iter *iter = s->private;
748 0 : return iter->pid_ns;
749 : }
750 :
751 : /*
752 : * This routine locks the ipc structure found at least at position pos.
753 : */
754 0 : static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
755 : loff_t *new_pos)
756 : {
757 0 : struct kern_ipc_perm *ipc;
758 0 : int total, id;
759 :
760 0 : total = 0;
761 0 : for (id = 0; id < pos && total < ids->in_use; id++) {
762 0 : ipc = idr_find(&ids->ipcs_idr, id);
763 0 : if (ipc != NULL)
764 0 : total++;
765 : }
766 :
767 0 : ipc = NULL;
768 0 : if (total >= ids->in_use)
769 0 : goto out;
770 :
771 0 : for (; pos < ipc_mni; pos++) {
772 0 : ipc = idr_find(&ids->ipcs_idr, pos);
773 0 : if (ipc != NULL) {
774 0 : rcu_read_lock();
775 0 : ipc_lock_object(ipc);
776 : break;
777 : }
778 : }
779 0 : out:
780 0 : *new_pos = pos + 1;
781 0 : return ipc;
782 : }
783 :
784 0 : static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
785 : {
786 0 : struct ipc_proc_iter *iter = s->private;
787 0 : struct ipc_proc_iface *iface = iter->iface;
788 0 : struct kern_ipc_perm *ipc = it;
789 :
790 : /* If we had an ipc id locked before, unlock it */
791 0 : if (ipc && ipc != SEQ_START_TOKEN)
792 0 : ipc_unlock(ipc);
793 :
794 0 : return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
795 : }
796 :
797 : /*
798 : * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
799 : * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
800 : */
801 0 : static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
802 : {
803 0 : struct ipc_proc_iter *iter = s->private;
804 0 : struct ipc_proc_iface *iface = iter->iface;
805 0 : struct ipc_ids *ids;
806 :
807 0 : ids = &iter->ns->ids[iface->ids];
808 :
809 : /*
810 : * Take the lock - this will be released by the corresponding
811 : * call to stop().
812 : */
813 0 : down_read(&ids->rwsem);
814 :
815 : /* pos < 0 is invalid */
816 0 : if (*pos < 0)
817 : return NULL;
818 :
819 : /* pos == 0 means header */
820 0 : if (*pos == 0)
821 : return SEQ_START_TOKEN;
822 :
823 : /* Find the (pos-1)th ipc */
824 0 : return sysvipc_find_ipc(ids, *pos - 1, pos);
825 : }
826 :
827 0 : static void sysvipc_proc_stop(struct seq_file *s, void *it)
828 : {
829 0 : struct kern_ipc_perm *ipc = it;
830 0 : struct ipc_proc_iter *iter = s->private;
831 0 : struct ipc_proc_iface *iface = iter->iface;
832 0 : struct ipc_ids *ids;
833 :
834 : /* If we had a locked structure, release it */
835 0 : if (ipc && ipc != SEQ_START_TOKEN)
836 0 : ipc_unlock(ipc);
837 :
838 0 : ids = &iter->ns->ids[iface->ids];
839 : /* Release the lock we took in start() */
840 0 : up_read(&ids->rwsem);
841 0 : }
842 :
843 0 : static int sysvipc_proc_show(struct seq_file *s, void *it)
844 : {
845 0 : struct ipc_proc_iter *iter = s->private;
846 0 : struct ipc_proc_iface *iface = iter->iface;
847 :
848 0 : if (it == SEQ_START_TOKEN) {
849 0 : seq_puts(s, iface->header);
850 0 : return 0;
851 : }
852 :
853 0 : return iface->show(s, it);
854 : }
855 :
856 : static const struct seq_operations sysvipc_proc_seqops = {
857 : .start = sysvipc_proc_start,
858 : .stop = sysvipc_proc_stop,
859 : .next = sysvipc_proc_next,
860 : .show = sysvipc_proc_show,
861 : };
862 :
863 0 : static int sysvipc_proc_open(struct inode *inode, struct file *file)
864 : {
865 0 : struct ipc_proc_iter *iter;
866 :
867 0 : iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
868 0 : if (!iter)
869 : return -ENOMEM;
870 :
871 0 : iter->iface = PDE_DATA(inode);
872 0 : iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
873 0 : iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
874 :
875 0 : return 0;
876 : }
877 :
878 0 : static int sysvipc_proc_release(struct inode *inode, struct file *file)
879 : {
880 0 : struct seq_file *seq = file->private_data;
881 0 : struct ipc_proc_iter *iter = seq->private;
882 0 : put_ipc_ns(iter->ns);
883 0 : put_pid_ns(iter->pid_ns);
884 0 : return seq_release_private(inode, file);
885 : }
886 :
887 : static const struct proc_ops sysvipc_proc_ops = {
888 : .proc_flags = PROC_ENTRY_PERMANENT,
889 : .proc_open = sysvipc_proc_open,
890 : .proc_read = seq_read,
891 : .proc_lseek = seq_lseek,
892 : .proc_release = sysvipc_proc_release,
893 : };
894 : #endif /* CONFIG_PROC_FS */
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