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sysvipc: fix the ipc structures initialization
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1da177e4
LT
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
624dffcb 10 * Manfred Spraul <manfred@colorfullife.com>
1da177e4
LT
11 * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
12 * Mingming Cao <cmm@us.ibm.com>
073115d6
SG
13 * Mar 2006 - support for audit of ipc object properties
14 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
73ea4130
KK
15 * Jun 2006 - namespaces ssupport
16 * OpenVZ, SWsoft Inc.
17 * Pavel Emelianov <xemul@openvz.org>
1da177e4
LT
18 */
19
1da177e4
LT
20#include <linux/mm.h>
21#include <linux/shm.h>
22#include <linux/init.h>
23#include <linux/msg.h>
1da177e4
LT
24#include <linux/vmalloc.h>
25#include <linux/slab.h>
c59ede7b 26#include <linux/capability.h>
1da177e4
LT
27#include <linux/highuid.h>
28#include <linux/security.h>
29#include <linux/rcupdate.h>
30#include <linux/workqueue.h>
ae781774
MW
31#include <linux/seq_file.h>
32#include <linux/proc_fs.h>
073115d6 33#include <linux/audit.h>
73ea4130 34#include <linux/nsproxy.h>
3e148c79 35#include <linux/rwsem.h>
b6b337ad 36#include <linux/memory.h>
ae5e1b22 37#include <linux/ipc_namespace.h>
1da177e4
LT
38
39#include <asm/unistd.h>
40
41#include "util.h"
42
ae781774
MW
43struct ipc_proc_iface {
44 const char *path;
45 const char *header;
73ea4130 46 int ids;
ae781774
MW
47 int (*show)(struct seq_file *, void *);
48};
49
73ea4130
KK
50struct ipc_namespace init_ipc_ns = {
51 .kref = {
52 .refcount = ATOMIC_INIT(2),
53 },
54};
55
4d89dc6a
ND
56atomic_t nr_ipc_ns = ATOMIC_INIT(1);
57
58
b6b337ad
ND
59#ifdef CONFIG_MEMORY_HOTPLUG
60
424450c1
ND
61static void ipc_memory_notifier(struct work_struct *work)
62{
63 ipcns_notify(IPCNS_MEMCHANGED);
64}
65
66static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
67
68
b6b337ad
ND
69static 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.
424450c1
ND
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.
b6b337ad 82 */
424450c1
ND
83 if (!work_pending(&ipc_memory_wq))
84 schedule_work(&ipc_memory_wq);
b6b337ad
ND
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
1da177e4
LT
99/**
100 * ipc_init - initialise IPC subsystem
101 *
102 * The various system5 IPC resources (semaphores, messages and shared
72fd4a35 103 * memory) are initialised
b6b337ad
ND
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.
1da177e4
LT
107 */
108
109static int __init ipc_init(void)
110{
111 sem_init();
112 msg_init();
113 shm_init();
b6b337ad
ND
114 hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
115 register_ipcns_notifier(&init_ipc_ns);
1da177e4
LT
116 return 0;
117}
118__initcall(ipc_init);
119
120/**
121 * ipc_init_ids - initialise IPC identifiers
122 * @ids: Identifier set
1da177e4 123 *
7ca7e564
ND
124 * Set up the sequence range to use for the ipc identifier range (limited
125 * below IPCMNI) then initialise the ids idr.
1da177e4
LT
126 */
127
7ca7e564 128void ipc_init_ids(struct ipc_ids *ids)
1da177e4 129{
3e148c79 130 init_rwsem(&ids->rw_mutex);
1da177e4 131
1da177e4 132 ids->in_use = 0;
1da177e4
LT
133 ids->seq = 0;
134 {
135 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
44f564a4
ZY
136 if (seq_limit > USHORT_MAX)
137 ids->seq_max = USHORT_MAX;
1da177e4
LT
138 else
139 ids->seq_max = seq_limit;
140 }
141
7ca7e564 142 idr_init(&ids->ipcs_idr);
1da177e4
LT
143}
144
ae781774 145#ifdef CONFIG_PROC_FS
9a32144e 146static const struct file_operations sysvipc_proc_fops;
ae781774 147/**
72fd4a35 148 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
ae781774
MW
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 */
154void __init ipc_init_proc_interface(const char *path, const char *header,
73ea4130 155 int ids, int (*show)(struct seq_file *, void *))
ae781774
MW
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
6a6375db
DL
168 pde = proc_create_data(path,
169 S_IRUGO, /* world readable */
170 NULL, /* parent dir */
171 &sysvipc_proc_fops,
172 iface);
173 if (!pde) {
ae781774
MW
174 kfree(iface);
175 }
176}
177#endif
178
1da177e4
LT
179/**
180 * ipc_findkey - find a key in an ipc identifier set
181 * @ids: Identifier set
182 * @key: The key to find
183 *
3e148c79 184 * Requires ipc_ids.rw_mutex locked.
7ca7e564
ND
185 * Returns the LOCKED pointer to the ipc structure if found or NULL
186 * if not.
f4566f04 187 * If key is found ipc points to the owning ipc structure
1da177e4
LT
188 */
189
7748dbfa 190static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
1da177e4 191{
7ca7e564
ND
192 struct kern_ipc_perm *ipc;
193 int next_id;
194 int total;
1da177e4 195
7ca7e564
ND
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)
1da177e4 200 continue;
7ca7e564
ND
201
202 if (ipc->key != key) {
203 total++;
204 continue;
205 }
206
207 ipc_lock_by_ptr(ipc);
208 return ipc;
1da177e4 209 }
7ca7e564
ND
210
211 return NULL;
1da177e4
LT
212}
213
7ca7e564
ND
214/**
215 * ipc_get_maxid - get the last assigned id
216 * @ids: IPC identifier set
217 *
3e148c79 218 * Called with ipc_ids.rw_mutex held.
1da177e4 219 */
1da177e4 220
7ca7e564
ND
221int 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;
1da177e4 229
7ca7e564
ND
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;
1da177e4
LT
243}
244
245/**
246 * ipc_addid - add an IPC identifier
247 * @ids: IPC identifier set
248 * @new: new IPC permission set
7ca7e564 249 * @size: limit for the number of used ids
1da177e4 250 *
f4566f04 251 * Add an entry 'new' to the IPC ids idr. The permissions object is
1da177e4 252 * initialised and the first free entry is set up and the id assigned
f4566f04 253 * is returned. The 'new' entry is returned in a locked state on success.
283bb7fa 254 * On failure the entry is not locked and a negative err-code is returned.
1da177e4 255 *
3e148c79 256 * Called with ipc_ids.rw_mutex held as a writer.
1da177e4
LT
257 */
258
259int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
260{
7ca7e564 261 int id, err;
1da177e4 262
7ca7e564
ND
263 if (size > IPCMNI)
264 size = IPCMNI;
265
266 if (ids->in_use >= size)
283bb7fa 267 return -ENOSPC;
7ca7e564 268
e00b4ff7
ND
269 spin_lock_init(&new->lock);
270 new->deleted = 0;
271 rcu_read_lock();
272 spin_lock(&new->lock);
273
7ca7e564 274 err = idr_get_new(&ids->ipcs_idr, new, &id);
e00b4ff7
ND
275 if (err) {
276 spin_unlock(&new->lock);
277 rcu_read_unlock();
283bb7fa 278 return err;
e00b4ff7 279 }
7ca7e564 280
1da177e4 281 ids->in_use++;
1da177e4
LT
282
283 new->cuid = new->uid = current->euid;
284 new->gid = new->cgid = current->egid;
285
286 new->seq = ids->seq++;
287 if(ids->seq > ids->seq_max)
288 ids->seq = 0;
289
48dea404 290 new->id = ipc_buildid(id, new->seq);
1da177e4
LT
291 return id;
292}
293
7748dbfa
ND
294/**
295 * ipcget_new - create a new ipc object
296 * @ns: namespace
f4566f04 297 * @ids: IPC identifer set
7748dbfa
ND
298 * @ops: the actual creation routine to call
299 * @params: its parameters
300 *
f4566f04
ND
301 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
302 * when the key is IPC_PRIVATE.
7748dbfa 303 */
b2d75cdd 304static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
7748dbfa
ND
305 struct ipc_ops *ops, struct ipc_params *params)
306{
307 int err;
283bb7fa 308retry:
7748dbfa
ND
309 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
310
311 if (!err)
312 return -ENOMEM;
313
3e148c79 314 down_write(&ids->rw_mutex);
7748dbfa 315 err = ops->getnew(ns, params);
3e148c79 316 up_write(&ids->rw_mutex);
7748dbfa 317
283bb7fa
PP
318 if (err == -EAGAIN)
319 goto retry;
320
7748dbfa
ND
321 return err;
322}
323
324/**
325 * ipc_check_perms - check security and permissions for an IPC
326 * @ipcp: ipc permission set
7748dbfa
ND
327 * @ops: the actual security routine to call
328 * @params: its parameters
f4566f04
ND
329 *
330 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
331 * when the key is not IPC_PRIVATE and that key already exists in the
332 * ids IDR.
333 *
334 * On success, the IPC id is returned.
335 *
3e148c79 336 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
7748dbfa
ND
337 */
338static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
339 struct ipc_params *params)
340{
341 int err;
342
343 if (ipcperms(ipcp, params->flg))
344 err = -EACCES;
345 else {
346 err = ops->associate(ipcp, params->flg);
347 if (!err)
348 err = ipcp->id;
349 }
350
351 return err;
352}
353
354/**
355 * ipcget_public - get an ipc object or create a new one
356 * @ns: namespace
f4566f04 357 * @ids: IPC identifer set
7748dbfa
ND
358 * @ops: the actual creation routine to call
359 * @params: its parameters
360 *
f4566f04
ND
361 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
362 * when the key is not IPC_PRIVATE.
363 * It adds a new entry if the key is not found and does some permission
364 * / security checkings if the key is found.
365 *
366 * On success, the ipc id is returned.
7748dbfa 367 */
b2d75cdd 368static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
7748dbfa
ND
369 struct ipc_ops *ops, struct ipc_params *params)
370{
371 struct kern_ipc_perm *ipcp;
372 int flg = params->flg;
373 int err;
283bb7fa 374retry:
7748dbfa
ND
375 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
376
3e148c79
ND
377 /*
378 * Take the lock as a writer since we are potentially going to add
379 * a new entry + read locks are not "upgradable"
380 */
381 down_write(&ids->rw_mutex);
7748dbfa
ND
382 ipcp = ipc_findkey(ids, params->key);
383 if (ipcp == NULL) {
384 /* key not used */
385 if (!(flg & IPC_CREAT))
386 err = -ENOENT;
387 else if (!err)
388 err = -ENOMEM;
389 else
390 err = ops->getnew(ns, params);
391 } else {
392 /* ipc object has been locked by ipc_findkey() */
393
394 if (flg & IPC_CREAT && flg & IPC_EXCL)
395 err = -EEXIST;
396 else {
397 err = 0;
398 if (ops->more_checks)
399 err = ops->more_checks(ipcp, params);
400 if (!err)
f4566f04
ND
401 /*
402 * ipc_check_perms returns the IPC id on
403 * success
404 */
7748dbfa
ND
405 err = ipc_check_perms(ipcp, ops, params);
406 }
407 ipc_unlock(ipcp);
408 }
3e148c79 409 up_write(&ids->rw_mutex);
7748dbfa 410
283bb7fa
PP
411 if (err == -EAGAIN)
412 goto retry;
413
7748dbfa
ND
414 return err;
415}
416
417
1da177e4
LT
418/**
419 * ipc_rmid - remove an IPC identifier
f4566f04
ND
420 * @ids: IPC identifier set
421 * @ipcp: ipc perm structure containing the identifier to remove
1da177e4 422 *
3e148c79
ND
423 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
424 * before this function is called, and remain locked on the exit.
1da177e4
LT
425 */
426
7ca7e564 427void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
1da177e4 428{
ce621f5b 429 int lid = ipcid_to_idx(ipcp->id);
7ca7e564
ND
430
431 idr_remove(&ids->ipcs_idr, lid);
1da177e4 432
1da177e4
LT
433 ids->in_use--;
434
7ca7e564
ND
435 ipcp->deleted = 1;
436
437 return;
1da177e4
LT
438}
439
440/**
441 * ipc_alloc - allocate ipc space
442 * @size: size desired
443 *
444 * Allocate memory from the appropriate pools and return a pointer to it.
445 * NULL is returned if the allocation fails
446 */
447
448void* ipc_alloc(int size)
449{
450 void* out;
451 if(size > PAGE_SIZE)
452 out = vmalloc(size);
453 else
454 out = kmalloc(size, GFP_KERNEL);
455 return out;
456}
457
458/**
459 * ipc_free - free ipc space
460 * @ptr: pointer returned by ipc_alloc
461 * @size: size of block
462 *
72fd4a35 463 * Free a block created with ipc_alloc(). The caller must know the size
1da177e4
LT
464 * used in the allocation call.
465 */
466
467void ipc_free(void* ptr, int size)
468{
469 if(size > PAGE_SIZE)
470 vfree(ptr);
471 else
472 kfree(ptr);
473}
474
475/*
476 * rcu allocations:
477 * There are three headers that are prepended to the actual allocation:
478 * - during use: ipc_rcu_hdr.
479 * - during the rcu grace period: ipc_rcu_grace.
480 * - [only if vmalloc]: ipc_rcu_sched.
481 * Their lifetime doesn't overlap, thus the headers share the same memory.
482 * Unlike a normal union, they are right-aligned, thus some container_of
483 * forward/backward casting is necessary:
484 */
485struct ipc_rcu_hdr
486{
487 int refcount;
488 int is_vmalloc;
489 void *data[0];
490};
491
492
493struct ipc_rcu_grace
494{
495 struct rcu_head rcu;
496 /* "void *" makes sure alignment of following data is sane. */
497 void *data[0];
498};
499
500struct ipc_rcu_sched
501{
502 struct work_struct work;
503 /* "void *" makes sure alignment of following data is sane. */
504 void *data[0];
505};
506
507#define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
508 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
509#define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
510 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
511
512static inline int rcu_use_vmalloc(int size)
513{
514 /* Too big for a single page? */
515 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
516 return 1;
517 return 0;
518}
519
520/**
521 * ipc_rcu_alloc - allocate ipc and rcu space
522 * @size: size desired
523 *
524 * Allocate memory for the rcu header structure + the object.
525 * Returns the pointer to the object.
526 * NULL is returned if the allocation fails.
527 */
528
529void* ipc_rcu_alloc(int size)
530{
531 void* out;
532 /*
533 * We prepend the allocation with the rcu struct, and
534 * workqueue if necessary (for vmalloc).
535 */
536 if (rcu_use_vmalloc(size)) {
537 out = vmalloc(HDRLEN_VMALLOC + size);
538 if (out) {
539 out += HDRLEN_VMALLOC;
540 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
541 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
542 }
543 } else {
544 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
545 if (out) {
546 out += HDRLEN_KMALLOC;
547 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
548 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
549 }
550 }
551
552 return out;
553}
554
555void ipc_rcu_getref(void *ptr)
556{
557 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
558}
559
65f27f38
DH
560static void ipc_do_vfree(struct work_struct *work)
561{
562 vfree(container_of(work, struct ipc_rcu_sched, work));
563}
564
1da177e4 565/**
1e5d5331
RD
566 * ipc_schedule_free - free ipc + rcu space
567 * @head: RCU callback structure for queued work
1da177e4
LT
568 *
569 * Since RCU callback function is called in bh,
72fd4a35 570 * we need to defer the vfree to schedule_work().
1da177e4
LT
571 */
572static void ipc_schedule_free(struct rcu_head *head)
573{
f4566f04
ND
574 struct ipc_rcu_grace *grace;
575 struct ipc_rcu_sched *sched;
576
577 grace = container_of(head, struct ipc_rcu_grace, rcu);
578 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
579 data[0]);
1da177e4 580
65f27f38 581 INIT_WORK(&sched->work, ipc_do_vfree);
1da177e4
LT
582 schedule_work(&sched->work);
583}
584
585/**
1e5d5331
RD
586 * ipc_immediate_free - free ipc + rcu space
587 * @head: RCU callback structure that contains pointer to be freed
1da177e4 588 *
72fd4a35 589 * Free from the RCU callback context.
1da177e4
LT
590 */
591static void ipc_immediate_free(struct rcu_head *head)
592{
593 struct ipc_rcu_grace *free =
594 container_of(head, struct ipc_rcu_grace, rcu);
595 kfree(free);
596}
597
598void ipc_rcu_putref(void *ptr)
599{
600 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
601 return;
602
603 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
604 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
605 ipc_schedule_free);
606 } else {
607 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
608 ipc_immediate_free);
609 }
610}
611
612/**
613 * ipcperms - check IPC permissions
614 * @ipcp: IPC permission set
615 * @flag: desired permission set.
616 *
617 * Check user, group, other permissions for access
618 * to ipc resources. return 0 if allowed
619 */
620
621int ipcperms (struct kern_ipc_perm *ipcp, short flag)
622{ /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
073115d6 623 int requested_mode, granted_mode, err;
1da177e4 624
073115d6
SG
625 if (unlikely((err = audit_ipc_obj(ipcp))))
626 return err;
1da177e4
LT
627 requested_mode = (flag >> 6) | (flag >> 3) | flag;
628 granted_mode = ipcp->mode;
629 if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
630 granted_mode >>= 6;
631 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
632 granted_mode >>= 3;
633 /* is there some bit set in requested_mode but not in granted_mode? */
634 if ((requested_mode & ~granted_mode & 0007) &&
635 !capable(CAP_IPC_OWNER))
636 return -1;
637
638 return security_ipc_permission(ipcp, flag);
639}
640
641/*
642 * Functions to convert between the kern_ipc_perm structure and the
643 * old/new ipc_perm structures
644 */
645
646/**
647 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
648 * @in: kernel permissions
649 * @out: new style IPC permissions
650 *
72fd4a35
RD
651 * Turn the kernel object @in into a set of permissions descriptions
652 * for returning to userspace (@out).
1da177e4
LT
653 */
654
655
656void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
657{
658 out->key = in->key;
659 out->uid = in->uid;
660 out->gid = in->gid;
661 out->cuid = in->cuid;
662 out->cgid = in->cgid;
663 out->mode = in->mode;
664 out->seq = in->seq;
665}
666
667/**
f4566f04 668 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
1da177e4
LT
669 * @in: new style IPC permissions
670 * @out: old style IPC permissions
671 *
72fd4a35
RD
672 * Turn the new style permissions object @in into a compatibility
673 * object and store it into the @out pointer.
1da177e4
LT
674 */
675
676void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
677{
678 out->key = in->key;
679 SET_UID(out->uid, in->uid);
680 SET_GID(out->gid, in->gid);
681 SET_UID(out->cuid, in->cuid);
682 SET_GID(out->cgid, in->cgid);
683 out->mode = in->mode;
684 out->seq = in->seq;
685}
686
f4566f04 687/**
3e148c79 688 * ipc_lock - Lock an ipc structure without rw_mutex held
f4566f04
ND
689 * @ids: IPC identifier set
690 * @id: ipc id to look for
691 *
692 * Look for an id in the ipc ids idr and lock the associated ipc object.
693 *
f4566f04
ND
694 * The ipc object is locked on exit.
695 */
696
7ca7e564 697struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
1da177e4 698{
7ca7e564 699 struct kern_ipc_perm *out;
ce621f5b 700 int lid = ipcid_to_idx(id);
1da177e4
LT
701
702 rcu_read_lock();
7ca7e564
ND
703 out = idr_find(&ids->ipcs_idr, lid);
704 if (out == NULL) {
1da177e4 705 rcu_read_unlock();
023a5355 706 return ERR_PTR(-EINVAL);
1da177e4 707 }
7ca7e564 708
1da177e4
LT
709 spin_lock(&out->lock);
710
711 /* ipc_rmid() may have already freed the ID while ipc_lock
712 * was spinning: here verify that the structure is still valid
713 */
714 if (out->deleted) {
715 spin_unlock(&out->lock);
716 rcu_read_unlock();
023a5355 717 return ERR_PTR(-EINVAL);
1da177e4 718 }
7ca7e564 719
1da177e4
LT
720 return out;
721}
722
b2d75cdd
PE
723struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
724{
725 struct kern_ipc_perm *out;
726
727 out = ipc_lock(ids, id);
728 if (IS_ERR(out))
729 return out;
730
731 if (ipc_checkid(out, id)) {
732 ipc_unlock(out);
733 return ERR_PTR(-EIDRM);
734 }
735
736 return out;
737}
738
739/**
740 * ipcget - Common sys_*get() code
741 * @ns : namsepace
742 * @ids : IPC identifier set
743 * @ops : operations to be called on ipc object creation, permission checks
744 * and further checks
745 * @params : the parameters needed by the previous operations.
746 *
747 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
748 */
749int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
750 struct ipc_ops *ops, struct ipc_params *params)
751{
752 if (params->key == IPC_PRIVATE)
753 return ipcget_new(ns, ids, ops, params);
754 else
755 return ipcget_public(ns, ids, ops, params);
756}
757
8f4a3809
PP
758/**
759 * ipc_update_perm - update the permissions of an IPC.
760 * @in: the permission given as input.
761 * @out: the permission of the ipc to set.
762 */
763void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
764{
765 out->uid = in->uid;
766 out->gid = in->gid;
767 out->mode = (out->mode & ~S_IRWXUGO)
768 | (in->mode & S_IRWXUGO);
769}
770
a5f75e7f
PP
771/**
772 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
773 * @ids: the table of ids where to look for the ipc
774 * @id: the id of the ipc to retrieve
775 * @cmd: the cmd to check
776 * @perm: the permission to set
777 * @extra_perm: one extra permission parameter used by msq
778 *
779 * This function does some common audit and permissions check for some IPC_XXX
780 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
781 * It must be called without any lock held and
782 * - retrieves the ipc with the given id in the given table.
783 * - performs some audit and permission check, depending on the given cmd
784 * - returns the ipc with both ipc and rw_mutex locks held in case of success
785 * or an err-code without any lock held otherwise.
786 */
787struct kern_ipc_perm *ipcctl_pre_down(struct ipc_ids *ids, int id, int cmd,
788 struct ipc64_perm *perm, int extra_perm)
789{
790 struct kern_ipc_perm *ipcp;
791 int err;
792
793 down_write(&ids->rw_mutex);
00c2bf85 794 ipcp = ipc_lock_check(ids, id);
a5f75e7f
PP
795 if (IS_ERR(ipcp)) {
796 err = PTR_ERR(ipcp);
797 goto out_up;
798 }
799
800 err = audit_ipc_obj(ipcp);
801 if (err)
802 goto out_unlock;
803
804 if (cmd == IPC_SET) {
805 err = audit_ipc_set_perm(extra_perm, perm->uid,
806 perm->gid, perm->mode);
807 if (err)
808 goto out_unlock;
809 }
810 if (current->euid == ipcp->cuid ||
811 current->euid == ipcp->uid || capable(CAP_SYS_ADMIN))
812 return ipcp;
813
814 err = -EPERM;
815out_unlock:
816 ipc_unlock(ipcp);
817out_up:
818 up_write(&ids->rw_mutex);
819 return ERR_PTR(err);
820}
821
1da177e4
LT
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.
72fd4a35 830 * The @cmd value is turned from an encoding command and version into
1da177e4
LT
831 * just the command code.
832 */
833
834int 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 */
ae781774
MW
845
846#ifdef CONFIG_PROC_FS
bc1fc6d8
EB
847struct ipc_proc_iter {
848 struct ipc_namespace *ns;
849 struct ipc_proc_iface *iface;
850};
851
7ca7e564
ND
852/*
853 * This routine locks the ipc structure found at least at position pos.
854 */
b524b9ad
AB
855static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
856 loff_t *new_pos)
ae781774 857{
7ca7e564
ND
858 struct kern_ipc_perm *ipc;
859 int total, id;
73ea4130 860
7ca7e564
ND
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 }
ae781774 867
7ca7e564
ND
868 if (total >= ids->in_use)
869 return NULL;
ae781774 870
7ca7e564
ND
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);
ae781774
MW
876 return ipc;
877 }
878 }
879
880 /* Out of range - return NULL to terminate iteration */
881 return NULL;
882}
883
7ca7e564
ND
884static 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
ed2ddbf8 894 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
7ca7e564
ND
895}
896
ae781774 897/*
f4566f04
ND
898 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
899 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
ae781774
MW
900 */
901static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
902{
bc1fc6d8
EB
903 struct ipc_proc_iter *iter = s->private;
904 struct ipc_proc_iface *iface = iter->iface;
73ea4130
KK
905 struct ipc_ids *ids;
906
ed2ddbf8 907 ids = &iter->ns->ids[iface->ids];
ae781774
MW
908
909 /*
910 * Take the lock - this will be released by the corresponding
911 * call to stop().
912 */
3e148c79 913 down_read(&ids->rw_mutex);
ae781774
MW
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 */
7ca7e564 924 return sysvipc_find_ipc(ids, *pos - 1, pos);
ae781774
MW
925}
926
927static void sysvipc_proc_stop(struct seq_file *s, void *it)
928{
929 struct kern_ipc_perm *ipc = it;
bc1fc6d8
EB
930 struct ipc_proc_iter *iter = s->private;
931 struct ipc_proc_iface *iface = iter->iface;
73ea4130 932 struct ipc_ids *ids;
ae781774 933
f4566f04 934 /* If we had a locked structure, release it */
ae781774
MW
935 if (ipc && ipc != SEQ_START_TOKEN)
936 ipc_unlock(ipc);
937
ed2ddbf8 938 ids = &iter->ns->ids[iface->ids];
ae781774 939 /* Release the lock we took in start() */
3e148c79 940 up_read(&ids->rw_mutex);
ae781774
MW
941}
942
943static int sysvipc_proc_show(struct seq_file *s, void *it)
944{
bc1fc6d8
EB
945 struct ipc_proc_iter *iter = s->private;
946 struct ipc_proc_iface *iface = iter->iface;
ae781774
MW
947
948 if (it == SEQ_START_TOKEN)
949 return seq_puts(s, iface->header);
950
951 return iface->show(s, it);
952}
953
954static 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
bc1fc6d8
EB
961static int sysvipc_proc_open(struct inode *inode, struct file *file)
962{
ae781774
MW
963 int ret;
964 struct seq_file *seq;
bc1fc6d8
EB
965 struct ipc_proc_iter *iter;
966
967 ret = -ENOMEM;
968 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
969 if (!iter)
970 goto out;
ae781774
MW
971
972 ret = seq_open(file, &sysvipc_proc_seqops);
bc1fc6d8
EB
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);
981out:
ae781774 982 return ret;
bc1fc6d8
EB
983out_kfree:
984 kfree(iter);
985 goto out;
986}
987
988static 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);
ae781774
MW
994}
995
9a32144e 996static const struct file_operations sysvipc_proc_fops = {
ae781774
MW
997 .open = sysvipc_proc_open,
998 .read = seq_read,
999 .llseek = seq_lseek,
bc1fc6d8 1000 .release = sysvipc_proc_release,
ae781774
MW
1001};
1002#endif /* CONFIG_PROC_FS */