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 */
ipc_init(void)89 static int __init ipc_init(void)
90 {
91 proc_mkdir("sysvipc", NULL);
92 sem_init();
93 msg_init();
94 shm_init();
95
96 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 = FIELD_SIZEOF(struct kern_ipc_perm, key),
104 .locks_mul = 1,
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 IPCMNI) 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 #ifdef CONFIG_CHECKPOINT_RESTORE
124 ids->next_id = -1;
125 #endif
126 }
127
128 #ifdef CONFIG_PROC_FS
129 static const struct file_operations sysvipc_proc_fops;
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 */
ipc_init_proc_interface(const char * path,const char * header,int ids,int (* show)(struct seq_file *,void *))137 void __init ipc_init_proc_interface(const char *path, const char *header,
138 int ids, int (*show)(struct seq_file *, void *))
139 {
140 struct proc_dir_entry *pde;
141 struct ipc_proc_iface *iface;
142
143 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
144 if (!iface)
145 return;
146 iface->path = path;
147 iface->header = header;
148 iface->ids = ids;
149 iface->show = show;
150
151 pde = proc_create_data(path,
152 S_IRUGO, /* world readable */
153 NULL, /* parent dir */
154 &sysvipc_proc_fops,
155 iface);
156 if (!pde)
157 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 */
ipc_findkey(struct ipc_ids * ids,key_t key)171 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
172 {
173 struct kern_ipc_perm *ipcp;
174
175 ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
176 ipc_kht_params);
177 if (!ipcp)
178 return NULL;
179
180 rcu_read_lock();
181 ipc_lock_object(ipcp);
182 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 */
ipc_idr_alloc(struct ipc_ids * ids,struct kern_ipc_perm * new)197 static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
198 {
199 int idx, next_id = -1;
200
201 #ifdef CONFIG_CHECKPOINT_RESTORE
202 next_id = ids->next_id;
203 ids->next_id = -1;
204 #endif
205
206 /*
207 * As soon as a new object is inserted into the idr,
208 * ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
209 * and the lockless preparations for ipc operations can start.
210 * This means especially: permission checks, audit calls, allocation
211 * of undo structures, ...
212 *
213 * Thus the object must be fully initialized, and if something fails,
214 * then the full tear-down sequence must be followed.
215 * (i.e.: set new->deleted, reduce refcount, call_rcu())
216 */
217
218 if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
219 new->seq = ids->seq++;
220 if (ids->seq > IPCID_SEQ_MAX)
221 ids->seq = 0;
222 idx = idr_alloc(&ids->ipcs_idr, new, 0, 0, GFP_NOWAIT);
223 } else {
224 new->seq = ipcid_to_seqx(next_id);
225 idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
226 0, GFP_NOWAIT);
227 }
228 if (idx >= 0)
229 new->id = SEQ_MULTIPLIER * new->seq + idx;
230 return idx;
231 }
232
233 /**
234 * ipc_addid - add an ipc identifier
235 * @ids: ipc identifier set
236 * @new: new ipc permission set
237 * @limit: limit for the number of used ids
238 *
239 * Add an entry 'new' to the ipc ids idr. The permissions object is
240 * initialised and the first free entry is set up and the index assigned
241 * is returned. The 'new' entry is returned in a locked state on success.
242 *
243 * On failure the entry is not locked and a negative err-code is returned.
244 * The caller must use ipc_rcu_putref() to free the identifier.
245 *
246 * Called with writer ipc_ids.rwsem held.
247 */
ipc_addid(struct ipc_ids * ids,struct kern_ipc_perm * new,int limit)248 int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
249 {
250 kuid_t euid;
251 kgid_t egid;
252 int idx, err;
253
254 /* 1) Initialize the refcount so that ipc_rcu_putref works */
255 refcount_set(&new->refcount, 1);
256
257 if (limit > IPCMNI)
258 limit = IPCMNI;
259
260 if (ids->in_use >= limit)
261 return -ENOSPC;
262
263 idr_preload(GFP_KERNEL);
264
265 spin_lock_init(&new->lock);
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 new->deleted = false;
274
275 idx = ipc_idr_alloc(ids, new);
276 idr_preload_end();
277
278 if (idx >= 0 && new->key != IPC_PRIVATE) {
279 err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
280 ipc_kht_params);
281 if (err < 0) {
282 idr_remove(&ids->ipcs_idr, idx);
283 idx = err;
284 }
285 }
286 if (idx < 0) {
287 new->deleted = true;
288 spin_unlock(&new->lock);
289 rcu_read_unlock();
290 return idx;
291 }
292
293 ids->in_use++;
294 if (idx > ids->max_idx)
295 ids->max_idx = idx;
296 return idx;
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 */
ipcget_new(struct ipc_namespace * ns,struct ipc_ids * ids,const struct ipc_ops * ops,struct ipc_params * params)309 static 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 */
ipc_check_perms(struct ipc_namespace * ns,struct kern_ipc_perm * ipcp,const struct ipc_ops * ops,struct ipc_params * params)335 static 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 */
ipcget_public(struct ipc_namespace * ns,struct ipc_ids * ids,const struct ipc_ops * ops,struct ipc_params * params)367 static 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 */
ipc_kht_remove(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)417 static 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 */
ipc_rmid(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)432 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
433 {
434 int idx = ipcid_to_idx(ipcp->id);
435
436 idr_remove(&ids->ipcs_idr, idx);
437 ipc_kht_remove(ids, ipcp);
438 ids->in_use--;
439 ipcp->deleted = true;
440
441 if (unlikely(idx == ids->max_idx)) {
442 do {
443 idx--;
444 if (idx == -1)
445 break;
446 } while (!idr_find(&ids->ipcs_idr, idx));
447 ids->max_idx = idx;
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 */
ipc_set_key_private(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)459 void 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
ipc_rcu_getref(struct kern_ipc_perm * ptr)465 bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
466 {
467 return refcount_inc_not_zero(&ptr->refcount);
468 }
469
ipc_rcu_putref(struct kern_ipc_perm * ptr,void (* func)(struct rcu_head * head))470 void 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 */
ipcperms(struct ipc_namespace * ns,struct kern_ipc_perm * ipcp,short flag)490 int 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 */
kernel_to_ipc64_perm(struct kern_ipc_perm * in,struct ipc64_perm * out)524 void 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 */
ipc64_perm_to_ipc_perm(struct ipc64_perm * in,struct ipc_perm * out)543 void 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 */
ipc_obtain_object_idr(struct ipc_ids * ids,int id)564 struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
565 {
566 struct kern_ipc_perm *out;
567 int idx = ipcid_to_idx(id);
568
569 out = idr_find(&ids->ipcs_idr, idx);
570 if (!out)
571 return ERR_PTR(-EINVAL);
572
573 return out;
574 }
575
576 /**
577 * ipc_obtain_object_check
578 * @ids: ipc identifier set
579 * @id: ipc id to look for
580 *
581 * Similar to ipc_obtain_object_idr() but also checks the ipc object
582 * sequence number.
583 *
584 * Call inside the RCU critical section.
585 * The ipc object is *not* locked on exit.
586 */
ipc_obtain_object_check(struct ipc_ids * ids,int id)587 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
588 {
589 struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
590
591 if (IS_ERR(out))
592 goto out;
593
594 if (ipc_checkid(out, id))
595 return ERR_PTR(-EINVAL);
596 out:
597 return out;
598 }
599
600 /**
601 * ipcget - Common sys_*get() code
602 * @ns: namespace
603 * @ids: ipc identifier set
604 * @ops: operations to be called on ipc object creation, permission checks
605 * and further checks
606 * @params: the parameters needed by the previous operations.
607 *
608 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
609 */
ipcget(struct ipc_namespace * ns,struct ipc_ids * ids,const struct ipc_ops * ops,struct ipc_params * params)610 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
611 const struct ipc_ops *ops, struct ipc_params *params)
612 {
613 if (params->key == IPC_PRIVATE)
614 return ipcget_new(ns, ids, ops, params);
615 else
616 return ipcget_public(ns, ids, ops, params);
617 }
618
619 /**
620 * ipc_update_perm - update the permissions of an ipc object
621 * @in: the permission given as input.
622 * @out: the permission of the ipc to set.
623 */
ipc_update_perm(struct ipc64_perm * in,struct kern_ipc_perm * out)624 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
625 {
626 kuid_t uid = make_kuid(current_user_ns(), in->uid);
627 kgid_t gid = make_kgid(current_user_ns(), in->gid);
628 if (!uid_valid(uid) || !gid_valid(gid))
629 return -EINVAL;
630
631 out->uid = uid;
632 out->gid = gid;
633 out->mode = (out->mode & ~S_IRWXUGO)
634 | (in->mode & S_IRWXUGO);
635
636 return 0;
637 }
638
639 /**
640 * ipcctl_obtain_check - retrieve an ipc object and check permissions
641 * @ns: ipc namespace
642 * @ids: the table of ids where to look for the ipc
643 * @id: the id of the ipc to retrieve
644 * @cmd: the cmd to check
645 * @perm: the permission to set
646 * @extra_perm: one extra permission parameter used by msq
647 *
648 * This function does some common audit and permissions check for some IPC_XXX
649 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
650 *
651 * It:
652 * - retrieves the ipc object with the given id in the given table.
653 * - performs some audit and permission check, depending on the given cmd
654 * - returns a pointer to the ipc object or otherwise, the corresponding
655 * error.
656 *
657 * Call holding the both the rwsem and the rcu read lock.
658 */
ipcctl_obtain_check(struct ipc_namespace * ns,struct ipc_ids * ids,int id,int cmd,struct ipc64_perm * perm,int extra_perm)659 struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
660 struct ipc_ids *ids, int id, int cmd,
661 struct ipc64_perm *perm, int extra_perm)
662 {
663 kuid_t euid;
664 int err = -EPERM;
665 struct kern_ipc_perm *ipcp;
666
667 ipcp = ipc_obtain_object_check(ids, id);
668 if (IS_ERR(ipcp)) {
669 err = PTR_ERR(ipcp);
670 goto err;
671 }
672
673 audit_ipc_obj(ipcp);
674 if (cmd == IPC_SET)
675 audit_ipc_set_perm(extra_perm, perm->uid,
676 perm->gid, perm->mode);
677
678 euid = current_euid();
679 if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
680 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
681 return ipcp; /* successful lookup */
682 err:
683 return ERR_PTR(err);
684 }
685
686 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
687
688
689 /**
690 * ipc_parse_version - ipc call version
691 * @cmd: pointer to command
692 *
693 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
694 * The @cmd value is turned from an encoding command and version into
695 * just the command code.
696 */
ipc_parse_version(int * cmd)697 int ipc_parse_version(int *cmd)
698 {
699 if (*cmd & IPC_64) {
700 *cmd ^= IPC_64;
701 return IPC_64;
702 } else {
703 return IPC_OLD;
704 }
705 }
706
707 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
708
709 #ifdef CONFIG_PROC_FS
710 struct ipc_proc_iter {
711 struct ipc_namespace *ns;
712 struct pid_namespace *pid_ns;
713 struct ipc_proc_iface *iface;
714 };
715
ipc_seq_pid_ns(struct seq_file * s)716 struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
717 {
718 struct ipc_proc_iter *iter = s->private;
719 return iter->pid_ns;
720 }
721
722 /*
723 * This routine locks the ipc structure found at least at position pos.
724 */
sysvipc_find_ipc(struct ipc_ids * ids,loff_t pos,loff_t * new_pos)725 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
726 loff_t *new_pos)
727 {
728 struct kern_ipc_perm *ipc;
729 int total, id;
730
731 total = 0;
732 for (id = 0; id < pos && total < ids->in_use; id++) {
733 ipc = idr_find(&ids->ipcs_idr, id);
734 if (ipc != NULL)
735 total++;
736 }
737
738 if (total >= ids->in_use)
739 return NULL;
740
741 for (; pos < IPCMNI; pos++) {
742 ipc = idr_find(&ids->ipcs_idr, pos);
743 if (ipc != NULL) {
744 *new_pos = pos + 1;
745 rcu_read_lock();
746 ipc_lock_object(ipc);
747 return ipc;
748 }
749 }
750
751 /* Out of range - return NULL to terminate iteration */
752 return NULL;
753 }
754
sysvipc_proc_next(struct seq_file * s,void * it,loff_t * pos)755 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
756 {
757 struct ipc_proc_iter *iter = s->private;
758 struct ipc_proc_iface *iface = iter->iface;
759 struct kern_ipc_perm *ipc = it;
760
761 /* If we had an ipc id locked before, unlock it */
762 if (ipc && ipc != SEQ_START_TOKEN)
763 ipc_unlock(ipc);
764
765 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
766 }
767
768 /*
769 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
770 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
771 */
sysvipc_proc_start(struct seq_file * s,loff_t * pos)772 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
773 {
774 struct ipc_proc_iter *iter = s->private;
775 struct ipc_proc_iface *iface = iter->iface;
776 struct ipc_ids *ids;
777
778 ids = &iter->ns->ids[iface->ids];
779
780 /*
781 * Take the lock - this will be released by the corresponding
782 * call to stop().
783 */
784 down_read(&ids->rwsem);
785
786 /* pos < 0 is invalid */
787 if (*pos < 0)
788 return NULL;
789
790 /* pos == 0 means header */
791 if (*pos == 0)
792 return SEQ_START_TOKEN;
793
794 /* Find the (pos-1)th ipc */
795 return sysvipc_find_ipc(ids, *pos - 1, pos);
796 }
797
sysvipc_proc_stop(struct seq_file * s,void * it)798 static void sysvipc_proc_stop(struct seq_file *s, void *it)
799 {
800 struct kern_ipc_perm *ipc = it;
801 struct ipc_proc_iter *iter = s->private;
802 struct ipc_proc_iface *iface = iter->iface;
803 struct ipc_ids *ids;
804
805 /* If we had a locked structure, release it */
806 if (ipc && ipc != SEQ_START_TOKEN)
807 ipc_unlock(ipc);
808
809 ids = &iter->ns->ids[iface->ids];
810 /* Release the lock we took in start() */
811 up_read(&ids->rwsem);
812 }
813
sysvipc_proc_show(struct seq_file * s,void * it)814 static int sysvipc_proc_show(struct seq_file *s, void *it)
815 {
816 struct ipc_proc_iter *iter = s->private;
817 struct ipc_proc_iface *iface = iter->iface;
818
819 if (it == SEQ_START_TOKEN) {
820 seq_puts(s, iface->header);
821 return 0;
822 }
823
824 return iface->show(s, it);
825 }
826
827 static const struct seq_operations sysvipc_proc_seqops = {
828 .start = sysvipc_proc_start,
829 .stop = sysvipc_proc_stop,
830 .next = sysvipc_proc_next,
831 .show = sysvipc_proc_show,
832 };
833
sysvipc_proc_open(struct inode * inode,struct file * file)834 static int sysvipc_proc_open(struct inode *inode, struct file *file)
835 {
836 struct ipc_proc_iter *iter;
837
838 iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
839 if (!iter)
840 return -ENOMEM;
841
842 iter->iface = PDE_DATA(inode);
843 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
844 iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
845
846 return 0;
847 }
848
sysvipc_proc_release(struct inode * inode,struct file * file)849 static int sysvipc_proc_release(struct inode *inode, struct file *file)
850 {
851 struct seq_file *seq = file->private_data;
852 struct ipc_proc_iter *iter = seq->private;
853 put_ipc_ns(iter->ns);
854 put_pid_ns(iter->pid_ns);
855 return seq_release_private(inode, file);
856 }
857
858 static const struct file_operations sysvipc_proc_fops = {
859 .open = sysvipc_proc_open,
860 .read = seq_read,
861 .llseek = seq_lseek,
862 .release = sysvipc_proc_release,
863 };
864 #endif /* CONFIG_PROC_FS */
865
