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
20 #include <linux/mm.h>
21 #include <linux/shm.h>
22 #include <linux/init.h>
23 #include <linux/msg.h>
24 #include <linux/vmalloc.h>
25 #include <linux/slab.h>
26 #include <linux/capability.h>
27 #include <linux/highuid.h>
28 #include <linux/security.h>
29 #include <linux/rcupdate.h>
30 #include <linux/workqueue.h>
31 #include <linux/seq_file.h>
32 #include <linux/proc_fs.h>
33 #include <linux/audit.h>
34 #include <linux/nsproxy.h>
35 #include <linux/rwsem.h>
36 #include <linux/memory.h>
37 #include <linux/ipc_namespace.h>
38
39 #include <asm/unistd.h>
40
41 #include "util.h"
42
43 struct ipc_proc_iface {
44 const char *path;
45 const char *header;
46 int ids;
47 int (*show)(struct seq_file *, void *);
48 };
49
50 struct ipc_namespace init_ipc_ns = {
51 .kref = {
52 .refcount = ATOMIC_INIT(2),
53 },
54 };
55
56 atomic_t nr_ipc_ns = ATOMIC_INIT(1);
57
58
59 #ifdef CONFIG_MEMORY_HOTPLUG
60
ipc_memory_notifier(struct work_struct * work)61 static void ipc_memory_notifier(struct work_struct *work)
62 {
63 ipcns_notify(IPCNS_MEMCHANGED);
64 }
65
66 static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
67
68
ipc_memory_callback(struct notifier_block * self,unsigned long action,void * arg)69 static int ipc_memory_callback(struct notifier_block *self,
70 unsigned long action, void *arg)
71 {
72 switch (action) {
73 case MEM_ONLINE: /* memory successfully brought online */
74 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
75 /*
76 * This is done by invoking the ipcns notifier chain with the
77 * IPC_MEMCHANGED event.
78 * In order not to keep the lock on the hotplug memory chain
79 * for too long, queue a work item that will, when waken up,
80 * activate the ipcns notification chain.
81 * No need to keep several ipc work items on the queue.
82 */
83 if (!work_pending(&ipc_memory_wq))
84 schedule_work(&ipc_memory_wq);
85 break;
86 case MEM_GOING_ONLINE:
87 case MEM_GOING_OFFLINE:
88 case MEM_CANCEL_ONLINE:
89 case MEM_CANCEL_OFFLINE:
90 default:
91 break;
92 }
93
94 return NOTIFY_OK;
95 }
96
97 #endif /* CONFIG_MEMORY_HOTPLUG */
98
99 /**
100 * ipc_init - initialise IPC subsystem
101 *
102 * The various system5 IPC resources (semaphores, messages and shared
103 * memory) are initialised
104 * A callback routine is registered into the memory hotplug notifier
105 * chain: since msgmni scales to lowmem this callback routine will be
106 * called upon successful memory add / remove to recompute msmgni.
107 */
108
ipc_init(void)109 static int __init ipc_init(void)
110 {
111 sem_init();
112 msg_init();
113 shm_init();
114 hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
115 register_ipcns_notifier(&init_ipc_ns);
116 return 0;
117 }
118 __initcall(ipc_init);
119
120 /**
121 * ipc_init_ids - initialise IPC identifiers
122 * @ids: Identifier set
123 *
124 * Set up the sequence range to use for the ipc identifier range (limited
125 * below IPCMNI) then initialise the ids idr.
126 */
127
ipc_init_ids(struct ipc_ids * ids)128 void ipc_init_ids(struct ipc_ids *ids)
129 {
130 init_rwsem(&ids->rw_mutex);
131
132 ids->in_use = 0;
133 ids->seq = 0;
134 {
135 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
136 if (seq_limit > USHORT_MAX)
137 ids->seq_max = USHORT_MAX;
138 else
139 ids->seq_max = seq_limit;
140 }
141
142 idr_init(&ids->ipcs_idr);
143 }
144
145 #ifdef CONFIG_PROC_FS
146 static const struct file_operations sysvipc_proc_fops;
147 /**
148 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
149 * @path: Path in procfs
150 * @header: Banner to be printed at the beginning of the file.
151 * @ids: ipc id table to iterate.
152 * @show: show routine.
153 */
ipc_init_proc_interface(const char * path,const char * header,int ids,int (* show)(struct seq_file *,void *))154 void __init ipc_init_proc_interface(const char *path, const char *header,
155 int ids, int (*show)(struct seq_file *, void *))
156 {
157 struct proc_dir_entry *pde;
158 struct ipc_proc_iface *iface;
159
160 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
161 if (!iface)
162 return;
163 iface->path = path;
164 iface->header = header;
165 iface->ids = ids;
166 iface->show = show;
167
168 pde = proc_create_data(path,
169 S_IRUGO, /* world readable */
170 NULL, /* parent dir */
171 &sysvipc_proc_fops,
172 iface);
173 if (!pde) {
174 kfree(iface);
175 }
176 }
177 #endif
178
179 /**
180 * ipc_findkey - find a key in an ipc identifier set
181 * @ids: Identifier set
182 * @key: The key to find
183 *
184 * Requires ipc_ids.rw_mutex locked.
185 * Returns the LOCKED pointer to the ipc structure if found or NULL
186 * if not.
187 * If key is found ipc points to the owning ipc structure
188 */
189
ipc_findkey(struct ipc_ids * ids,key_t key)190 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
191 {
192 struct kern_ipc_perm *ipc;
193 int next_id;
194 int total;
195
196 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
197 ipc = idr_find(&ids->ipcs_idr, next_id);
198
199 if (ipc == NULL)
200 continue;
201
202 if (ipc->key != key) {
203 total++;
204 continue;
205 }
206
207 ipc_lock_by_ptr(ipc);
208 return ipc;
209 }
210
211 return NULL;
212 }
213
214 /**
215 * ipc_get_maxid - get the last assigned id
216 * @ids: IPC identifier set
217 *
218 * Called with ipc_ids.rw_mutex held.
219 */
220
ipc_get_maxid(struct ipc_ids * ids)221 int ipc_get_maxid(struct ipc_ids *ids)
222 {
223 struct kern_ipc_perm *ipc;
224 int max_id = -1;
225 int total, id;
226
227 if (ids->in_use == 0)
228 return -1;
229
230 if (ids->in_use == IPCMNI)
231 return IPCMNI - 1;
232
233 /* Look for the last assigned id */
234 total = 0;
235 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
236 ipc = idr_find(&ids->ipcs_idr, id);
237 if (ipc != NULL) {
238 max_id = id;
239 total++;
240 }
241 }
242 return max_id;
243 }
244
245 /**
246 * ipc_addid - add an IPC identifier
247 * @ids: IPC identifier set
248 * @new: new IPC permission set
249 * @size: limit for the number of used ids
250 *
251 * Add an entry 'new' to the IPC ids idr. The permissions object is
252 * initialised and the first free entry is set up and the id assigned
253 * is returned. The 'new' entry is returned in a locked state on success.
254 * On failure the entry is not locked and a negative err-code is returned.
255 *
256 * Called with ipc_ids.rw_mutex held as a writer.
257 */
258
ipc_addid(struct ipc_ids * ids,struct kern_ipc_perm * new,int size)259 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
260 {
261 uid_t euid;
262 gid_t egid;
263 int id, err;
264
265 if (size > IPCMNI)
266 size = IPCMNI;
267
268 if (ids->in_use >= size)
269 return -ENOSPC;
270
271 spin_lock_init(&new->lock);
272 new->deleted = 0;
273 rcu_read_lock();
274 spin_lock(&new->lock);
275
276 err = idr_get_new(&ids->ipcs_idr, new, &id);
277 if (err) {
278 spin_unlock(&new->lock);
279 rcu_read_unlock();
280 return err;
281 }
282
283 ids->in_use++;
284
285 current_euid_egid(&euid, &egid);
286 new->cuid = new->uid = euid;
287 new->gid = new->cgid = egid;
288
289 new->seq = ids->seq++;
290 if(ids->seq > ids->seq_max)
291 ids->seq = 0;
292
293 new->id = ipc_buildid(id, new->seq);
294 return id;
295 }
296
297 /**
298 * ipcget_new - create a new ipc object
299 * @ns: namespace
300 * @ids: IPC identifer set
301 * @ops: the actual creation routine to call
302 * @params: its parameters
303 *
304 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
305 * when the key is IPC_PRIVATE.
306 */
ipcget_new(struct ipc_namespace * ns,struct ipc_ids * ids,struct ipc_ops * ops,struct ipc_params * params)307 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
308 struct ipc_ops *ops, struct ipc_params *params)
309 {
310 int err;
311 retry:
312 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
313
314 if (!err)
315 return -ENOMEM;
316
317 down_write(&ids->rw_mutex);
318 err = ops->getnew(ns, params);
319 up_write(&ids->rw_mutex);
320
321 if (err == -EAGAIN)
322 goto retry;
323
324 return err;
325 }
326
327 /**
328 * ipc_check_perms - check security and permissions for an IPC
329 * @ipcp: ipc permission set
330 * @ops: the actual security routine to call
331 * @params: its parameters
332 *
333 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
334 * when the key is not IPC_PRIVATE and that key already exists in the
335 * ids IDR.
336 *
337 * On success, the IPC id is returned.
338 *
339 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
340 */
ipc_check_perms(struct kern_ipc_perm * ipcp,struct ipc_ops * ops,struct ipc_params * params)341 static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
342 struct ipc_params *params)
343 {
344 int err;
345
346 if (ipcperms(ipcp, params->flg))
347 err = -EACCES;
348 else {
349 err = ops->associate(ipcp, params->flg);
350 if (!err)
351 err = ipcp->id;
352 }
353
354 return err;
355 }
356
357 /**
358 * ipcget_public - get an ipc object or create a new one
359 * @ns: namespace
360 * @ids: IPC identifer set
361 * @ops: the actual creation routine to call
362 * @params: its parameters
363 *
364 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
365 * when the key is not IPC_PRIVATE.
366 * It adds a new entry if the key is not found and does some permission
367 * / security checkings if the key is found.
368 *
369 * On success, the ipc id is returned.
370 */
ipcget_public(struct ipc_namespace * ns,struct ipc_ids * ids,struct ipc_ops * ops,struct ipc_params * params)371 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
372 struct ipc_ops *ops, struct ipc_params *params)
373 {
374 struct kern_ipc_perm *ipcp;
375 int flg = params->flg;
376 int err;
377 retry:
378 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
379
380 /*
381 * Take the lock as a writer since we are potentially going to add
382 * a new entry + read locks are not "upgradable"
383 */
384 down_write(&ids->rw_mutex);
385 ipcp = ipc_findkey(ids, params->key);
386 if (ipcp == NULL) {
387 /* key not used */
388 if (!(flg & IPC_CREAT))
389 err = -ENOENT;
390 else if (!err)
391 err = -ENOMEM;
392 else
393 err = ops->getnew(ns, params);
394 } else {
395 /* ipc object has been locked by ipc_findkey() */
396
397 if (flg & IPC_CREAT && flg & IPC_EXCL)
398 err = -EEXIST;
399 else {
400 err = 0;
401 if (ops->more_checks)
402 err = ops->more_checks(ipcp, params);
403 if (!err)
404 /*
405 * ipc_check_perms returns the IPC id on
406 * success
407 */
408 err = ipc_check_perms(ipcp, ops, params);
409 }
410 ipc_unlock(ipcp);
411 }
412 up_write(&ids->rw_mutex);
413
414 if (err == -EAGAIN)
415 goto retry;
416
417 return err;
418 }
419
420
421 /**
422 * ipc_rmid - remove an IPC identifier
423 * @ids: IPC identifier set
424 * @ipcp: ipc perm structure containing the identifier to remove
425 *
426 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
427 * before this function is called, and remain locked on the exit.
428 */
429
ipc_rmid(struct ipc_ids * ids,struct kern_ipc_perm * ipcp)430 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
431 {
432 int lid = ipcid_to_idx(ipcp->id);
433
434 idr_remove(&ids->ipcs_idr, lid);
435
436 ids->in_use--;
437
438 ipcp->deleted = 1;
439
440 return;
441 }
442
443 /**
444 * ipc_alloc - allocate ipc space
445 * @size: size desired
446 *
447 * Allocate memory from the appropriate pools and return a pointer to it.
448 * NULL is returned if the allocation fails
449 */
450
ipc_alloc(int size)451 void* ipc_alloc(int size)
452 {
453 void* out;
454 if(size > PAGE_SIZE)
455 out = vmalloc(size);
456 else
457 out = kmalloc(size, GFP_KERNEL);
458 return out;
459 }
460
461 /**
462 * ipc_free - free ipc space
463 * @ptr: pointer returned by ipc_alloc
464 * @size: size of block
465 *
466 * Free a block created with ipc_alloc(). The caller must know the size
467 * used in the allocation call.
468 */
469
ipc_free(void * ptr,int size)470 void ipc_free(void* ptr, int size)
471 {
472 if(size > PAGE_SIZE)
473 vfree(ptr);
474 else
475 kfree(ptr);
476 }
477
478 /*
479 * rcu allocations:
480 * There are three headers that are prepended to the actual allocation:
481 * - during use: ipc_rcu_hdr.
482 * - during the rcu grace period: ipc_rcu_grace.
483 * - [only if vmalloc]: ipc_rcu_sched.
484 * Their lifetime doesn't overlap, thus the headers share the same memory.
485 * Unlike a normal union, they are right-aligned, thus some container_of
486 * forward/backward casting is necessary:
487 */
488 struct ipc_rcu_hdr
489 {
490 int refcount;
491 int is_vmalloc;
492 void *data[0];
493 };
494
495
496 struct ipc_rcu_grace
497 {
498 struct rcu_head rcu;
499 /* "void *" makes sure alignment of following data is sane. */
500 void *data[0];
501 };
502
503 struct ipc_rcu_sched
504 {
505 struct work_struct work;
506 /* "void *" makes sure alignment of following data is sane. */
507 void *data[0];
508 };
509
510 #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
511 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
512 #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
513 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
514
rcu_use_vmalloc(int size)515 static inline int rcu_use_vmalloc(int size)
516 {
517 /* Too big for a single page? */
518 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
519 return 1;
520 return 0;
521 }
522
523 /**
524 * ipc_rcu_alloc - allocate ipc and rcu space
525 * @size: size desired
526 *
527 * Allocate memory for the rcu header structure + the object.
528 * Returns the pointer to the object.
529 * NULL is returned if the allocation fails.
530 */
531
ipc_rcu_alloc(int size)532 void* ipc_rcu_alloc(int size)
533 {
534 void* out;
535 /*
536 * We prepend the allocation with the rcu struct, and
537 * workqueue if necessary (for vmalloc).
538 */
539 if (rcu_use_vmalloc(size)) {
540 out = vmalloc(HDRLEN_VMALLOC + size);
541 if (out) {
542 out += HDRLEN_VMALLOC;
543 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
544 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
545 }
546 } else {
547 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
548 if (out) {
549 out += HDRLEN_KMALLOC;
550 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
551 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
552 }
553 }
554
555 return out;
556 }
557
ipc_rcu_getref(void * ptr)558 void ipc_rcu_getref(void *ptr)
559 {
560 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
561 }
562
ipc_do_vfree(struct work_struct * work)563 static void ipc_do_vfree(struct work_struct *work)
564 {
565 vfree(container_of(work, struct ipc_rcu_sched, work));
566 }
567
568 /**
569 * ipc_schedule_free - free ipc + rcu space
570 * @head: RCU callback structure for queued work
571 *
572 * Since RCU callback function is called in bh,
573 * we need to defer the vfree to schedule_work().
574 */
ipc_schedule_free(struct rcu_head * head)575 static void ipc_schedule_free(struct rcu_head *head)
576 {
577 struct ipc_rcu_grace *grace;
578 struct ipc_rcu_sched *sched;
579
580 grace = container_of(head, struct ipc_rcu_grace, rcu);
581 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
582 data[0]);
583
584 INIT_WORK(&sched->work, ipc_do_vfree);
585 schedule_work(&sched->work);
586 }
587
588 /**
589 * ipc_immediate_free - free ipc + rcu space
590 * @head: RCU callback structure that contains pointer to be freed
591 *
592 * Free from the RCU callback context.
593 */
ipc_immediate_free(struct rcu_head * head)594 static void ipc_immediate_free(struct rcu_head *head)
595 {
596 struct ipc_rcu_grace *free =
597 container_of(head, struct ipc_rcu_grace, rcu);
598 kfree(free);
599 }
600
ipc_rcu_putref(void * ptr)601 void ipc_rcu_putref(void *ptr)
602 {
603 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
604 return;
605
606 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
607 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
608 ipc_schedule_free);
609 } else {
610 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
611 ipc_immediate_free);
612 }
613 }
614
615 /**
616 * ipcperms - check IPC permissions
617 * @ipcp: IPC permission set
618 * @flag: desired permission set.
619 *
620 * Check user, group, other permissions for access
621 * to ipc resources. return 0 if allowed
622 */
623
ipcperms(struct kern_ipc_perm * ipcp,short flag)624 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
625 { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
626 uid_t euid = current_euid();
627 int requested_mode, granted_mode;
628
629 audit_ipc_obj(ipcp);
630 requested_mode = (flag >> 6) | (flag >> 3) | flag;
631 granted_mode = ipcp->mode;
632 if (euid == ipcp->cuid ||
633 euid == ipcp->uid)
634 granted_mode >>= 6;
635 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
636 granted_mode >>= 3;
637 /* is there some bit set in requested_mode but not in granted_mode? */
638 if ((requested_mode & ~granted_mode & 0007) &&
639 !capable(CAP_IPC_OWNER))
640 return -1;
641
642 return security_ipc_permission(ipcp, flag);
643 }
644
645 /*
646 * Functions to convert between the kern_ipc_perm structure and the
647 * old/new ipc_perm structures
648 */
649
650 /**
651 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
652 * @in: kernel permissions
653 * @out: new style IPC permissions
654 *
655 * Turn the kernel object @in into a set of permissions descriptions
656 * for returning to userspace (@out).
657 */
658
659
kernel_to_ipc64_perm(struct kern_ipc_perm * in,struct ipc64_perm * out)660 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
661 {
662 out->key = in->key;
663 out->uid = in->uid;
664 out->gid = in->gid;
665 out->cuid = in->cuid;
666 out->cgid = in->cgid;
667 out->mode = in->mode;
668 out->seq = in->seq;
669 }
670
671 /**
672 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
673 * @in: new style IPC permissions
674 * @out: old style IPC permissions
675 *
676 * Turn the new style permissions object @in into a compatibility
677 * object and store it into the @out pointer.
678 */
679
ipc64_perm_to_ipc_perm(struct ipc64_perm * in,struct ipc_perm * out)680 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
681 {
682 out->key = in->key;
683 SET_UID(out->uid, in->uid);
684 SET_GID(out->gid, in->gid);
685 SET_UID(out->cuid, in->cuid);
686 SET_GID(out->cgid, in->cgid);
687 out->mode = in->mode;
688 out->seq = in->seq;
689 }
690
691 /**
692 * ipc_lock - Lock an ipc structure without rw_mutex held
693 * @ids: IPC identifier set
694 * @id: ipc id to look for
695 *
696 * Look for an id in the ipc ids idr and lock the associated ipc object.
697 *
698 * The ipc object is locked on exit.
699 */
700
ipc_lock(struct ipc_ids * ids,int id)701 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
702 {
703 struct kern_ipc_perm *out;
704 int lid = ipcid_to_idx(id);
705
706 rcu_read_lock();
707 out = idr_find(&ids->ipcs_idr, lid);
708 if (out == NULL) {
709 rcu_read_unlock();
710 return ERR_PTR(-EINVAL);
711 }
712
713 spin_lock(&out->lock);
714
715 /* ipc_rmid() may have already freed the ID while ipc_lock
716 * was spinning: here verify that the structure is still valid
717 */
718 if (out->deleted) {
719 spin_unlock(&out->lock);
720 rcu_read_unlock();
721 return ERR_PTR(-EINVAL);
722 }
723
724 return out;
725 }
726
ipc_lock_check(struct ipc_ids * ids,int id)727 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
728 {
729 struct kern_ipc_perm *out;
730
731 out = ipc_lock(ids, id);
732 if (IS_ERR(out))
733 return out;
734
735 if (ipc_checkid(out, id)) {
736 ipc_unlock(out);
737 return ERR_PTR(-EIDRM);
738 }
739
740 return out;
741 }
742
743 /**
744 * ipcget - Common sys_*get() code
745 * @ns : namsepace
746 * @ids : IPC identifier set
747 * @ops : operations to be called on ipc object creation, permission checks
748 * and further checks
749 * @params : the parameters needed by the previous operations.
750 *
751 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
752 */
ipcget(struct ipc_namespace * ns,struct ipc_ids * ids,struct ipc_ops * ops,struct ipc_params * params)753 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
754 struct ipc_ops *ops, struct ipc_params *params)
755 {
756 if (params->key == IPC_PRIVATE)
757 return ipcget_new(ns, ids, ops, params);
758 else
759 return ipcget_public(ns, ids, ops, params);
760 }
761
762 /**
763 * ipc_update_perm - update the permissions of an IPC.
764 * @in: the permission given as input.
765 * @out: the permission of the ipc to set.
766 */
ipc_update_perm(struct ipc64_perm * in,struct kern_ipc_perm * out)767 void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
768 {
769 out->uid = in->uid;
770 out->gid = in->gid;
771 out->mode = (out->mode & ~S_IRWXUGO)
772 | (in->mode & S_IRWXUGO);
773 }
774
775 /**
776 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
777 * @ids: the table of ids where to look for the ipc
778 * @id: the id of the ipc to retrieve
779 * @cmd: the cmd to check
780 * @perm: the permission to set
781 * @extra_perm: one extra permission parameter used by msq
782 *
783 * This function does some common audit and permissions check for some IPC_XXX
784 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
785 * It must be called without any lock held and
786 * - retrieves the ipc with the given id in the given table.
787 * - performs some audit and permission check, depending on the given cmd
788 * - returns the ipc with both ipc and rw_mutex locks held in case of success
789 * or an err-code without any lock held otherwise.
790 */
ipcctl_pre_down(struct ipc_ids * ids,int id,int cmd,struct ipc64_perm * perm,int extra_perm)791 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
792 struct ipc64_perm *perm, int extra_perm)
793 {
794 struct kern_ipc_perm *ipcp;
795 uid_t euid;
796 int err;
797
798 down_write(&ids->rw_mutex);
799 ipcp = ipc_lock_check(ids, id);
800 if (IS_ERR(ipcp)) {
801 err = PTR_ERR(ipcp);
802 goto out_up;
803 }
804
805 audit_ipc_obj(ipcp);
806 if (cmd == IPC_SET)
807 audit_ipc_set_perm(extra_perm, perm->uid,
808 perm->gid, perm->mode);
809
810 euid = current_euid();
811 if (euid == ipcp->cuid ||
812 euid == ipcp->uid || capable(CAP_SYS_ADMIN))
813 return ipcp;
814
815 err = -EPERM;
816 ipc_unlock(ipcp);
817 out_up:
818 up_write(&ids->rw_mutex);
819 return ERR_PTR(err);
820 }
821
822 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
823
824
825 /**
826 * ipc_parse_version - IPC call version
827 * @cmd: pointer to command
828 *
829 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
830 * The @cmd value is turned from an encoding command and version into
831 * just the command code.
832 */
833
ipc_parse_version(int * cmd)834 int ipc_parse_version (int *cmd)
835 {
836 if (*cmd & IPC_64) {
837 *cmd ^= IPC_64;
838 return IPC_64;
839 } else {
840 return IPC_OLD;
841 }
842 }
843
844 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
845
846 #ifdef CONFIG_PROC_FS
847 struct ipc_proc_iter {
848 struct ipc_namespace *ns;
849 struct ipc_proc_iface *iface;
850 };
851
852 /*
853 * This routine locks the ipc structure found at least at position pos.
854 */
sysvipc_find_ipc(struct ipc_ids * ids,loff_t pos,loff_t * new_pos)855 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
856 loff_t *new_pos)
857 {
858 struct kern_ipc_perm *ipc;
859 int total, id;
860
861 total = 0;
862 for (id = 0; id < pos && total < ids->in_use; id++) {
863 ipc = idr_find(&ids->ipcs_idr, id);
864 if (ipc != NULL)
865 total++;
866 }
867
868 if (total >= ids->in_use)
869 return NULL;
870
871 for ( ; pos < IPCMNI; pos++) {
872 ipc = idr_find(&ids->ipcs_idr, pos);
873 if (ipc != NULL) {
874 *new_pos = pos + 1;
875 ipc_lock_by_ptr(ipc);
876 return ipc;
877 }
878 }
879
880 /* Out of range - return NULL to terminate iteration */
881 return NULL;
882 }
883
sysvipc_proc_next(struct seq_file * s,void * it,loff_t * pos)884 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
885 {
886 struct ipc_proc_iter *iter = s->private;
887 struct ipc_proc_iface *iface = iter->iface;
888 struct kern_ipc_perm *ipc = it;
889
890 /* If we had an ipc id locked before, unlock it */
891 if (ipc && ipc != SEQ_START_TOKEN)
892 ipc_unlock(ipc);
893
894 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
895 }
896
897 /*
898 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
899 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
900 */
sysvipc_proc_start(struct seq_file * s,loff_t * pos)901 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
902 {
903 struct ipc_proc_iter *iter = s->private;
904 struct ipc_proc_iface *iface = iter->iface;
905 struct ipc_ids *ids;
906
907 ids = &iter->ns->ids[iface->ids];
908
909 /*
910 * Take the lock - this will be released by the corresponding
911 * call to stop().
912 */
913 down_read(&ids->rw_mutex);
914
915 /* pos < 0 is invalid */
916 if (*pos < 0)
917 return NULL;
918
919 /* pos == 0 means header */
920 if (*pos == 0)
921 return SEQ_START_TOKEN;
922
923 /* Find the (pos-1)th ipc */
924 return sysvipc_find_ipc(ids, *pos - 1, pos);
925 }
926
sysvipc_proc_stop(struct seq_file * s,void * it)927 static void sysvipc_proc_stop(struct seq_file *s, void *it)
928 {
929 struct kern_ipc_perm *ipc = it;
930 struct ipc_proc_iter *iter = s->private;
931 struct ipc_proc_iface *iface = iter->iface;
932 struct ipc_ids *ids;
933
934 /* If we had a locked structure, release it */
935 if (ipc && ipc != SEQ_START_TOKEN)
936 ipc_unlock(ipc);
937
938 ids = &iter->ns->ids[iface->ids];
939 /* Release the lock we took in start() */
940 up_read(&ids->rw_mutex);
941 }
942
sysvipc_proc_show(struct seq_file * s,void * it)943 static int sysvipc_proc_show(struct seq_file *s, void *it)
944 {
945 struct ipc_proc_iter *iter = s->private;
946 struct ipc_proc_iface *iface = iter->iface;
947
948 if (it == SEQ_START_TOKEN)
949 return seq_puts(s, iface->header);
950
951 return iface->show(s, it);
952 }
953
954 static struct seq_operations sysvipc_proc_seqops = {
955 .start = sysvipc_proc_start,
956 .stop = sysvipc_proc_stop,
957 .next = sysvipc_proc_next,
958 .show = sysvipc_proc_show,
959 };
960
sysvipc_proc_open(struct inode * inode,struct file * file)961 static int sysvipc_proc_open(struct inode *inode, struct file *file)
962 {
963 int ret;
964 struct seq_file *seq;
965 struct ipc_proc_iter *iter;
966
967 ret = -ENOMEM;
968 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
969 if (!iter)
970 goto out;
971
972 ret = seq_open(file, &sysvipc_proc_seqops);
973 if (ret)
974 goto out_kfree;
975
976 seq = file->private_data;
977 seq->private = iter;
978
979 iter->iface = PDE(inode)->data;
980 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
981 out:
982 return ret;
983 out_kfree:
984 kfree(iter);
985 goto out;
986 }
987
sysvipc_proc_release(struct inode * inode,struct file * file)988 static int sysvipc_proc_release(struct inode *inode, struct file *file)
989 {
990 struct seq_file *seq = file->private_data;
991 struct ipc_proc_iter *iter = seq->private;
992 put_ipc_ns(iter->ns);
993 return seq_release_private(inode, file);
994 }
995
996 static const struct file_operations sysvipc_proc_fops = {
997 .open = sysvipc_proc_open,
998 .read = seq_read,
999 .llseek = seq_lseek,
1000 .release = sysvipc_proc_release,
1001 };
1002 #endif /* CONFIG_PROC_FS */
1003