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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
b6b337ad
ND
50#ifdef CONFIG_MEMORY_HOTPLUG
51
424450c1
ND
52static void ipc_memory_notifier(struct work_struct *work)
53{
54 ipcns_notify(IPCNS_MEMCHANGED);
55}
56
57static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
58
59
b6b337ad
ND
60static int ipc_memory_callback(struct notifier_block *self,
61 unsigned long action, void *arg)
62{
63 switch (action) {
64 case MEM_ONLINE: /* memory successfully brought online */
65 case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */
66 /*
67 * This is done by invoking the ipcns notifier chain with the
68 * IPC_MEMCHANGED event.
424450c1
ND
69 * In order not to keep the lock on the hotplug memory chain
70 * for too long, queue a work item that will, when waken up,
71 * activate the ipcns notification chain.
72 * No need to keep several ipc work items on the queue.
b6b337ad 73 */
424450c1
ND
74 if (!work_pending(&ipc_memory_wq))
75 schedule_work(&ipc_memory_wq);
b6b337ad
ND
76 break;
77 case MEM_GOING_ONLINE:
78 case MEM_GOING_OFFLINE:
79 case MEM_CANCEL_ONLINE:
80 case MEM_CANCEL_OFFLINE:
81 default:
82 break;
83 }
84
85 return NOTIFY_OK;
86}
87
88#endif /* CONFIG_MEMORY_HOTPLUG */
89
1da177e4
LT
90/**
91 * ipc_init - initialise IPC subsystem
92 *
93 * The various system5 IPC resources (semaphores, messages and shared
72fd4a35 94 * memory) are initialised
b6b337ad
ND
95 * A callback routine is registered into the memory hotplug notifier
96 * chain: since msgmni scales to lowmem this callback routine will be
97 * called upon successful memory add / remove to recompute msmgni.
1da177e4
LT
98 */
99
100static int __init ipc_init(void)
101{
102 sem_init();
103 msg_init();
104 shm_init();
b6b337ad
ND
105 hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI);
106 register_ipcns_notifier(&init_ipc_ns);
1da177e4
LT
107 return 0;
108}
109__initcall(ipc_init);
110
111/**
112 * ipc_init_ids - initialise IPC identifiers
113 * @ids: Identifier set
1da177e4 114 *
7ca7e564
ND
115 * Set up the sequence range to use for the ipc identifier range (limited
116 * below IPCMNI) then initialise the ids idr.
1da177e4
LT
117 */
118
7ca7e564 119void ipc_init_ids(struct ipc_ids *ids)
1da177e4 120{
3e148c79 121 init_rwsem(&ids->rw_mutex);
1da177e4 122
1da177e4 123 ids->in_use = 0;
1da177e4
LT
124 ids->seq = 0;
125 {
126 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
4be929be
AD
127 if (seq_limit > USHRT_MAX)
128 ids->seq_max = USHRT_MAX;
1da177e4
LT
129 else
130 ids->seq_max = seq_limit;
131 }
132
7ca7e564 133 idr_init(&ids->ipcs_idr);
1da177e4
LT
134}
135
ae781774 136#ifdef CONFIG_PROC_FS
9a32144e 137static const struct file_operations sysvipc_proc_fops;
ae781774 138/**
72fd4a35 139 * ipc_init_proc_interface - Create a proc interface for sysipc types using a seq_file interface.
ae781774
MW
140 * @path: Path in procfs
141 * @header: Banner to be printed at the beginning of the file.
142 * @ids: ipc id table to iterate.
143 * @show: show routine.
144 */
145void __init ipc_init_proc_interface(const char *path, const char *header,
73ea4130 146 int ids, int (*show)(struct seq_file *, void *))
ae781774
MW
147{
148 struct proc_dir_entry *pde;
149 struct ipc_proc_iface *iface;
150
151 iface = kmalloc(sizeof(*iface), GFP_KERNEL);
152 if (!iface)
153 return;
154 iface->path = path;
155 iface->header = header;
156 iface->ids = ids;
157 iface->show = show;
158
6a6375db
DL
159 pde = proc_create_data(path,
160 S_IRUGO, /* world readable */
161 NULL, /* parent dir */
162 &sysvipc_proc_fops,
163 iface);
164 if (!pde) {
ae781774
MW
165 kfree(iface);
166 }
167}
168#endif
169
1da177e4
LT
170/**
171 * ipc_findkey - find a key in an ipc identifier set
172 * @ids: Identifier set
173 * @key: The key to find
174 *
3e148c79 175 * Requires ipc_ids.rw_mutex locked.
7ca7e564
ND
176 * Returns the LOCKED pointer to the ipc structure if found or NULL
177 * if not.
f4566f04 178 * If key is found ipc points to the owning ipc structure
1da177e4
LT
179 */
180
7748dbfa 181static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
1da177e4 182{
7ca7e564
ND
183 struct kern_ipc_perm *ipc;
184 int next_id;
185 int total;
1da177e4 186
7ca7e564
ND
187 for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
188 ipc = idr_find(&ids->ipcs_idr, next_id);
189
190 if (ipc == NULL)
1da177e4 191 continue;
7ca7e564
ND
192
193 if (ipc->key != key) {
194 total++;
195 continue;
196 }
197
198 ipc_lock_by_ptr(ipc);
199 return ipc;
1da177e4 200 }
7ca7e564
ND
201
202 return NULL;
1da177e4
LT
203}
204
7ca7e564
ND
205/**
206 * ipc_get_maxid - get the last assigned id
207 * @ids: IPC identifier set
208 *
3e148c79 209 * Called with ipc_ids.rw_mutex held.
1da177e4 210 */
1da177e4 211
7ca7e564
ND
212int ipc_get_maxid(struct ipc_ids *ids)
213{
214 struct kern_ipc_perm *ipc;
215 int max_id = -1;
216 int total, id;
217
218 if (ids->in_use == 0)
219 return -1;
1da177e4 220
7ca7e564
ND
221 if (ids->in_use == IPCMNI)
222 return IPCMNI - 1;
223
224 /* Look for the last assigned id */
225 total = 0;
226 for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
227 ipc = idr_find(&ids->ipcs_idr, id);
228 if (ipc != NULL) {
229 max_id = id;
230 total++;
231 }
232 }
233 return max_id;
1da177e4
LT
234}
235
236/**
237 * ipc_addid - add an IPC identifier
238 * @ids: IPC identifier set
239 * @new: new IPC permission set
7ca7e564 240 * @size: limit for the number of used ids
1da177e4 241 *
f4566f04 242 * Add an entry 'new' to the IPC ids idr. The permissions object is
1da177e4 243 * initialised and the first free entry is set up and the id assigned
f4566f04 244 * is returned. The 'new' entry is returned in a locked state on success.
283bb7fa 245 * On failure the entry is not locked and a negative err-code is returned.
1da177e4 246 *
3e148c79 247 * Called with ipc_ids.rw_mutex held as a writer.
1da177e4
LT
248 */
249
250int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
251{
414c0708
DH
252 uid_t euid;
253 gid_t egid;
7ca7e564 254 int id, err;
1da177e4 255
7ca7e564
ND
256 if (size > IPCMNI)
257 size = IPCMNI;
258
259 if (ids->in_use >= size)
283bb7fa 260 return -ENOSPC;
7ca7e564 261
e00b4ff7
ND
262 spin_lock_init(&new->lock);
263 new->deleted = 0;
264 rcu_read_lock();
265 spin_lock(&new->lock);
266
7ca7e564 267 err = idr_get_new(&ids->ipcs_idr, new, &id);
e00b4ff7
ND
268 if (err) {
269 spin_unlock(&new->lock);
270 rcu_read_unlock();
283bb7fa 271 return err;
e00b4ff7 272 }
7ca7e564 273
1da177e4 274 ids->in_use++;
1da177e4 275
414c0708
DH
276 current_euid_egid(&euid, &egid);
277 new->cuid = new->uid = euid;
278 new->gid = new->cgid = egid;
1da177e4
LT
279
280 new->seq = ids->seq++;
281 if(ids->seq > ids->seq_max)
282 ids->seq = 0;
283
48dea404 284 new->id = ipc_buildid(id, new->seq);
1da177e4
LT
285 return id;
286}
287
7748dbfa
ND
288/**
289 * ipcget_new - create a new ipc object
290 * @ns: namespace
f4566f04 291 * @ids: IPC identifer set
7748dbfa
ND
292 * @ops: the actual creation routine to call
293 * @params: its parameters
294 *
f4566f04
ND
295 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
296 * when the key is IPC_PRIVATE.
7748dbfa 297 */
b2d75cdd 298static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
7748dbfa
ND
299 struct ipc_ops *ops, struct ipc_params *params)
300{
301 int err;
283bb7fa 302retry:
7748dbfa
ND
303 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
304
305 if (!err)
306 return -ENOMEM;
307
3e148c79 308 down_write(&ids->rw_mutex);
7748dbfa 309 err = ops->getnew(ns, params);
3e148c79 310 up_write(&ids->rw_mutex);
7748dbfa 311
283bb7fa
PP
312 if (err == -EAGAIN)
313 goto retry;
314
7748dbfa
ND
315 return err;
316}
317
318/**
319 * ipc_check_perms - check security and permissions for an IPC
6213cfe8 320 * @ns: IPC namespace
7748dbfa 321 * @ipcp: ipc permission set
7748dbfa
ND
322 * @ops: the actual security routine to call
323 * @params: its parameters
f4566f04
ND
324 *
325 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
326 * when the key is not IPC_PRIVATE and that key already exists in the
327 * ids IDR.
328 *
329 * On success, the IPC id is returned.
330 *
3e148c79 331 * It is called with ipc_ids.rw_mutex and ipcp->lock held.
7748dbfa 332 */
b0e77598
SH
333static int ipc_check_perms(struct ipc_namespace *ns,
334 struct kern_ipc_perm *ipcp,
335 struct ipc_ops *ops,
336 struct ipc_params *params)
7748dbfa
ND
337{
338 int err;
339
b0e77598 340 if (ipcperms(ns, ipcp, params->flg))
7748dbfa
ND
341 err = -EACCES;
342 else {
343 err = ops->associate(ipcp, params->flg);
344 if (!err)
345 err = ipcp->id;
346 }
347
348 return err;
349}
350
351/**
352 * ipcget_public - get an ipc object or create a new one
353 * @ns: namespace
f4566f04 354 * @ids: IPC identifer set
7748dbfa
ND
355 * @ops: the actual creation routine to call
356 * @params: its parameters
357 *
f4566f04
ND
358 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
359 * when the key is not IPC_PRIVATE.
360 * It adds a new entry if the key is not found and does some permission
361 * / security checkings if the key is found.
362 *
363 * On success, the ipc id is returned.
7748dbfa 364 */
b2d75cdd 365static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
7748dbfa
ND
366 struct ipc_ops *ops, struct ipc_params *params)
367{
368 struct kern_ipc_perm *ipcp;
369 int flg = params->flg;
370 int err;
283bb7fa 371retry:
7748dbfa
ND
372 err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
373
3e148c79
ND
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->rw_mutex);
7748dbfa
ND
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 if (!err)
385 err = -ENOMEM;
386 else
387 err = ops->getnew(ns, params);
388 } else {
389 /* ipc object has been locked by ipc_findkey() */
390
391 if (flg & IPC_CREAT && flg & IPC_EXCL)
392 err = -EEXIST;
393 else {
394 err = 0;
395 if (ops->more_checks)
396 err = ops->more_checks(ipcp, params);
397 if (!err)
f4566f04
ND
398 /*
399 * ipc_check_perms returns the IPC id on
400 * success
401 */
b0e77598 402 err = ipc_check_perms(ns, ipcp, ops, params);
7748dbfa
ND
403 }
404 ipc_unlock(ipcp);
405 }
3e148c79 406 up_write(&ids->rw_mutex);
7748dbfa 407
283bb7fa
PP
408 if (err == -EAGAIN)
409 goto retry;
410
7748dbfa
ND
411 return err;
412}
413
414
1da177e4
LT
415/**
416 * ipc_rmid - remove an IPC identifier
f4566f04
ND
417 * @ids: IPC identifier set
418 * @ipcp: ipc perm structure containing the identifier to remove
1da177e4 419 *
3e148c79
ND
420 * ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
421 * before this function is called, and remain locked on the exit.
1da177e4
LT
422 */
423
7ca7e564 424void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
1da177e4 425{
ce621f5b 426 int lid = ipcid_to_idx(ipcp->id);
7ca7e564
ND
427
428 idr_remove(&ids->ipcs_idr, lid);
1da177e4 429
1da177e4
LT
430 ids->in_use--;
431
7ca7e564
ND
432 ipcp->deleted = 1;
433
434 return;
1da177e4
LT
435}
436
437/**
438 * ipc_alloc - allocate ipc space
439 * @size: size desired
440 *
441 * Allocate memory from the appropriate pools and return a pointer to it.
442 * NULL is returned if the allocation fails
443 */
444
445void* ipc_alloc(int size)
446{
447 void* out;
448 if(size > PAGE_SIZE)
449 out = vmalloc(size);
450 else
451 out = kmalloc(size, GFP_KERNEL);
452 return out;
453}
454
455/**
456 * ipc_free - free ipc space
457 * @ptr: pointer returned by ipc_alloc
458 * @size: size of block
459 *
72fd4a35 460 * Free a block created with ipc_alloc(). The caller must know the size
1da177e4
LT
461 * used in the allocation call.
462 */
463
464void ipc_free(void* ptr, int size)
465{
466 if(size > PAGE_SIZE)
467 vfree(ptr);
468 else
469 kfree(ptr);
470}
471
472/*
473 * rcu allocations:
474 * There are three headers that are prepended to the actual allocation:
475 * - during use: ipc_rcu_hdr.
476 * - during the rcu grace period: ipc_rcu_grace.
477 * - [only if vmalloc]: ipc_rcu_sched.
478 * Their lifetime doesn't overlap, thus the headers share the same memory.
479 * Unlike a normal union, they are right-aligned, thus some container_of
480 * forward/backward casting is necessary:
481 */
482struct ipc_rcu_hdr
483{
484 int refcount;
485 int is_vmalloc;
486 void *data[0];
487};
488
489
490struct ipc_rcu_grace
491{
492 struct rcu_head rcu;
493 /* "void *" makes sure alignment of following data is sane. */
494 void *data[0];
495};
496
497struct ipc_rcu_sched
498{
499 struct work_struct work;
500 /* "void *" makes sure alignment of following data is sane. */
501 void *data[0];
502};
503
504#define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
505 sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
506#define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
507 sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
508
509static inline int rcu_use_vmalloc(int size)
510{
511 /* Too big for a single page? */
512 if (HDRLEN_KMALLOC + size > PAGE_SIZE)
513 return 1;
514 return 0;
515}
516
517/**
518 * ipc_rcu_alloc - allocate ipc and rcu space
519 * @size: size desired
520 *
521 * Allocate memory for the rcu header structure + the object.
522 * Returns the pointer to the object.
523 * NULL is returned if the allocation fails.
524 */
525
526void* ipc_rcu_alloc(int size)
527{
528 void* out;
529 /*
530 * We prepend the allocation with the rcu struct, and
531 * workqueue if necessary (for vmalloc).
532 */
533 if (rcu_use_vmalloc(size)) {
534 out = vmalloc(HDRLEN_VMALLOC + size);
535 if (out) {
536 out += HDRLEN_VMALLOC;
537 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
538 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
539 }
540 } else {
541 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
542 if (out) {
543 out += HDRLEN_KMALLOC;
544 container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
545 container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
546 }
547 }
548
549 return out;
550}
551
552void ipc_rcu_getref(void *ptr)
553{
554 container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
555}
556
65f27f38
DH
557static void ipc_do_vfree(struct work_struct *work)
558{
559 vfree(container_of(work, struct ipc_rcu_sched, work));
560}
561
1da177e4 562/**
1e5d5331
RD
563 * ipc_schedule_free - free ipc + rcu space
564 * @head: RCU callback structure for queued work
1da177e4
LT
565 *
566 * Since RCU callback function is called in bh,
72fd4a35 567 * we need to defer the vfree to schedule_work().
1da177e4
LT
568 */
569static void ipc_schedule_free(struct rcu_head *head)
570{
f4566f04
ND
571 struct ipc_rcu_grace *grace;
572 struct ipc_rcu_sched *sched;
573
574 grace = container_of(head, struct ipc_rcu_grace, rcu);
575 sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
576 data[0]);
1da177e4 577
65f27f38 578 INIT_WORK(&sched->work, ipc_do_vfree);
1da177e4
LT
579 schedule_work(&sched->work);
580}
581
1da177e4
LT
582void ipc_rcu_putref(void *ptr)
583{
584 if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
585 return;
586
587 if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
588 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
589 ipc_schedule_free);
590 } else {
d4ee9aa3 591 kfree_rcu(container_of(ptr, struct ipc_rcu_grace, data), rcu);
1da177e4
LT
592 }
593}
594
595/**
596 * ipcperms - check IPC permissions
6213cfe8 597 * @ns: IPC namespace
1da177e4
LT
598 * @ipcp: IPC permission set
599 * @flag: desired permission set.
600 *
601 * Check user, group, other permissions for access
602 * to ipc resources. return 0 if allowed
b0e77598
SH
603 *
604 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
1da177e4
LT
605 */
606
b0e77598
SH
607int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
608{
414c0708 609 uid_t euid = current_euid();
a33e6751 610 int requested_mode, granted_mode;
1da177e4 611
a33e6751 612 audit_ipc_obj(ipcp);
1da177e4
LT
613 requested_mode = (flag >> 6) | (flag >> 3) | flag;
614 granted_mode = ipcp->mode;
414c0708
DH
615 if (euid == ipcp->cuid ||
616 euid == ipcp->uid)
1da177e4
LT
617 granted_mode >>= 6;
618 else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
619 granted_mode >>= 3;
620 /* is there some bit set in requested_mode but not in granted_mode? */
621 if ((requested_mode & ~granted_mode & 0007) &&
b0e77598 622 !ns_capable(ns->user_ns, CAP_IPC_OWNER))
1da177e4
LT
623 return -1;
624
625 return security_ipc_permission(ipcp, flag);
626}
627
628/*
629 * Functions to convert between the kern_ipc_perm structure and the
630 * old/new ipc_perm structures
631 */
632
633/**
634 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
635 * @in: kernel permissions
636 * @out: new style IPC permissions
637 *
72fd4a35
RD
638 * Turn the kernel object @in into a set of permissions descriptions
639 * for returning to userspace (@out).
1da177e4
LT
640 */
641
642
643void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
644{
645 out->key = in->key;
646 out->uid = in->uid;
647 out->gid = in->gid;
648 out->cuid = in->cuid;
649 out->cgid = in->cgid;
650 out->mode = in->mode;
651 out->seq = in->seq;
652}
653
654/**
f4566f04 655 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
1da177e4
LT
656 * @in: new style IPC permissions
657 * @out: old style IPC permissions
658 *
72fd4a35
RD
659 * Turn the new style permissions object @in into a compatibility
660 * object and store it into the @out pointer.
1da177e4
LT
661 */
662
663void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
664{
665 out->key = in->key;
666 SET_UID(out->uid, in->uid);
667 SET_GID(out->gid, in->gid);
668 SET_UID(out->cuid, in->cuid);
669 SET_GID(out->cgid, in->cgid);
670 out->mode = in->mode;
671 out->seq = in->seq;
672}
673
f4566f04 674/**
3e148c79 675 * ipc_lock - Lock an ipc structure without rw_mutex held
f4566f04
ND
676 * @ids: IPC identifier set
677 * @id: ipc id to look for
678 *
679 * Look for an id in the ipc ids idr and lock the associated ipc object.
680 *
f4566f04
ND
681 * The ipc object is locked on exit.
682 */
683
7ca7e564 684struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
1da177e4 685{
7ca7e564 686 struct kern_ipc_perm *out;
ce621f5b 687 int lid = ipcid_to_idx(id);
1da177e4
LT
688
689 rcu_read_lock();
7ca7e564
ND
690 out = idr_find(&ids->ipcs_idr, lid);
691 if (out == NULL) {
1da177e4 692 rcu_read_unlock();
023a5355 693 return ERR_PTR(-EINVAL);
1da177e4 694 }
7ca7e564 695
1da177e4
LT
696 spin_lock(&out->lock);
697
698 /* ipc_rmid() may have already freed the ID while ipc_lock
699 * was spinning: here verify that the structure is still valid
700 */
701 if (out->deleted) {
702 spin_unlock(&out->lock);
703 rcu_read_unlock();
023a5355 704 return ERR_PTR(-EINVAL);
1da177e4 705 }
7ca7e564 706
1da177e4
LT
707 return out;
708}
709
b2d75cdd
PE
710struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
711{
712 struct kern_ipc_perm *out;
713
714 out = ipc_lock(ids, id);
715 if (IS_ERR(out))
716 return out;
717
718 if (ipc_checkid(out, id)) {
719 ipc_unlock(out);
720 return ERR_PTR(-EIDRM);
721 }
722
723 return out;
724}
725
726/**
727 * ipcget - Common sys_*get() code
728 * @ns : namsepace
729 * @ids : IPC identifier set
730 * @ops : operations to be called on ipc object creation, permission checks
731 * and further checks
732 * @params : the parameters needed by the previous operations.
733 *
734 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
735 */
736int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
737 struct ipc_ops *ops, struct ipc_params *params)
738{
739 if (params->key == IPC_PRIVATE)
740 return ipcget_new(ns, ids, ops, params);
741 else
742 return ipcget_public(ns, ids, ops, params);
743}
744
8f4a3809
PP
745/**
746 * ipc_update_perm - update the permissions of an IPC.
747 * @in: the permission given as input.
748 * @out: the permission of the ipc to set.
749 */
750void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
751{
752 out->uid = in->uid;
753 out->gid = in->gid;
754 out->mode = (out->mode & ~S_IRWXUGO)
755 | (in->mode & S_IRWXUGO);
756}
757
a5f75e7f
PP
758/**
759 * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
6213cfe8 760 * @ns: the ipc namespace
a5f75e7f
PP
761 * @ids: the table of ids where to look for the ipc
762 * @id: the id of the ipc to retrieve
763 * @cmd: the cmd to check
764 * @perm: the permission to set
765 * @extra_perm: one extra permission parameter used by msq
766 *
767 * This function does some common audit and permissions check for some IPC_XXX
768 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
769 * It must be called without any lock held and
770 * - retrieves the ipc with the given id in the given table.
771 * - performs some audit and permission check, depending on the given cmd
772 * - returns the ipc with both ipc and rw_mutex locks held in case of success
773 * or an err-code without any lock held otherwise.
774 */
b0e77598
SH
775struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
776 struct ipc_ids *ids, int id, int cmd,
a5f75e7f
PP
777 struct ipc64_perm *perm, int extra_perm)
778{
779 struct kern_ipc_perm *ipcp;
414c0708 780 uid_t euid;
a5f75e7f
PP
781 int err;
782
783 down_write(&ids->rw_mutex);
00c2bf85 784 ipcp = ipc_lock_check(ids, id);
a5f75e7f
PP
785 if (IS_ERR(ipcp)) {
786 err = PTR_ERR(ipcp);
787 goto out_up;
788 }
789
a33e6751 790 audit_ipc_obj(ipcp);
e816f370
AV
791 if (cmd == IPC_SET)
792 audit_ipc_set_perm(extra_perm, perm->uid,
a5f75e7f 793 perm->gid, perm->mode);
414c0708
DH
794
795 euid = current_euid();
b0e77598
SH
796 if (euid == ipcp->cuid || euid == ipcp->uid ||
797 ns_capable(ns->user_ns, CAP_SYS_ADMIN))
a5f75e7f
PP
798 return ipcp;
799
800 err = -EPERM;
a5f75e7f
PP
801 ipc_unlock(ipcp);
802out_up:
803 up_write(&ids->rw_mutex);
804 return ERR_PTR(err);
805}
806
1da177e4
LT
807#ifdef __ARCH_WANT_IPC_PARSE_VERSION
808
809
810/**
811 * ipc_parse_version - IPC call version
812 * @cmd: pointer to command
813 *
814 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
72fd4a35 815 * The @cmd value is turned from an encoding command and version into
1da177e4
LT
816 * just the command code.
817 */
818
819int ipc_parse_version (int *cmd)
820{
821 if (*cmd & IPC_64) {
822 *cmd ^= IPC_64;
823 return IPC_64;
824 } else {
825 return IPC_OLD;
826 }
827}
828
829#endif /* __ARCH_WANT_IPC_PARSE_VERSION */
ae781774
MW
830
831#ifdef CONFIG_PROC_FS
bc1fc6d8
EB
832struct ipc_proc_iter {
833 struct ipc_namespace *ns;
834 struct ipc_proc_iface *iface;
835};
836
7ca7e564
ND
837/*
838 * This routine locks the ipc structure found at least at position pos.
839 */
b524b9ad
AB
840static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
841 loff_t *new_pos)
ae781774 842{
7ca7e564
ND
843 struct kern_ipc_perm *ipc;
844 int total, id;
73ea4130 845
7ca7e564
ND
846 total = 0;
847 for (id = 0; id < pos && total < ids->in_use; id++) {
848 ipc = idr_find(&ids->ipcs_idr, id);
849 if (ipc != NULL)
850 total++;
851 }
ae781774 852
7ca7e564
ND
853 if (total >= ids->in_use)
854 return NULL;
ae781774 855
7ca7e564
ND
856 for ( ; pos < IPCMNI; pos++) {
857 ipc = idr_find(&ids->ipcs_idr, pos);
858 if (ipc != NULL) {
859 *new_pos = pos + 1;
860 ipc_lock_by_ptr(ipc);
ae781774
MW
861 return ipc;
862 }
863 }
864
865 /* Out of range - return NULL to terminate iteration */
866 return NULL;
867}
868
7ca7e564
ND
869static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
870{
871 struct ipc_proc_iter *iter = s->private;
872 struct ipc_proc_iface *iface = iter->iface;
873 struct kern_ipc_perm *ipc = it;
874
875 /* If we had an ipc id locked before, unlock it */
876 if (ipc && ipc != SEQ_START_TOKEN)
877 ipc_unlock(ipc);
878
ed2ddbf8 879 return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
7ca7e564
ND
880}
881
ae781774 882/*
f4566f04
ND
883 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
884 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
ae781774
MW
885 */
886static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
887{
bc1fc6d8
EB
888 struct ipc_proc_iter *iter = s->private;
889 struct ipc_proc_iface *iface = iter->iface;
73ea4130
KK
890 struct ipc_ids *ids;
891
ed2ddbf8 892 ids = &iter->ns->ids[iface->ids];
ae781774
MW
893
894 /*
895 * Take the lock - this will be released by the corresponding
896 * call to stop().
897 */
3e148c79 898 down_read(&ids->rw_mutex);
ae781774
MW
899
900 /* pos < 0 is invalid */
901 if (*pos < 0)
902 return NULL;
903
904 /* pos == 0 means header */
905 if (*pos == 0)
906 return SEQ_START_TOKEN;
907
908 /* Find the (pos-1)th ipc */
7ca7e564 909 return sysvipc_find_ipc(ids, *pos - 1, pos);
ae781774
MW
910}
911
912static void sysvipc_proc_stop(struct seq_file *s, void *it)
913{
914 struct kern_ipc_perm *ipc = it;
bc1fc6d8
EB
915 struct ipc_proc_iter *iter = s->private;
916 struct ipc_proc_iface *iface = iter->iface;
73ea4130 917 struct ipc_ids *ids;
ae781774 918
f4566f04 919 /* If we had a locked structure, release it */
ae781774
MW
920 if (ipc && ipc != SEQ_START_TOKEN)
921 ipc_unlock(ipc);
922
ed2ddbf8 923 ids = &iter->ns->ids[iface->ids];
ae781774 924 /* Release the lock we took in start() */
3e148c79 925 up_read(&ids->rw_mutex);
ae781774
MW
926}
927
928static int sysvipc_proc_show(struct seq_file *s, void *it)
929{
bc1fc6d8
EB
930 struct ipc_proc_iter *iter = s->private;
931 struct ipc_proc_iface *iface = iter->iface;
ae781774
MW
932
933 if (it == SEQ_START_TOKEN)
934 return seq_puts(s, iface->header);
935
936 return iface->show(s, it);
937}
938
88e9d34c 939static const struct seq_operations sysvipc_proc_seqops = {
ae781774
MW
940 .start = sysvipc_proc_start,
941 .stop = sysvipc_proc_stop,
942 .next = sysvipc_proc_next,
943 .show = sysvipc_proc_show,
944};
945
bc1fc6d8
EB
946static int sysvipc_proc_open(struct inode *inode, struct file *file)
947{
ae781774
MW
948 int ret;
949 struct seq_file *seq;
bc1fc6d8
EB
950 struct ipc_proc_iter *iter;
951
952 ret = -ENOMEM;
953 iter = kmalloc(sizeof(*iter), GFP_KERNEL);
954 if (!iter)
955 goto out;
ae781774
MW
956
957 ret = seq_open(file, &sysvipc_proc_seqops);
bc1fc6d8
EB
958 if (ret)
959 goto out_kfree;
960
961 seq = file->private_data;
962 seq->private = iter;
963
964 iter->iface = PDE(inode)->data;
965 iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
966out:
ae781774 967 return ret;
bc1fc6d8
EB
968out_kfree:
969 kfree(iter);
970 goto out;
971}
972
973static int sysvipc_proc_release(struct inode *inode, struct file *file)
974{
975 struct seq_file *seq = file->private_data;
976 struct ipc_proc_iter *iter = seq->private;
977 put_ipc_ns(iter->ns);
978 return seq_release_private(inode, file);
ae781774
MW
979}
980
9a32144e 981static const struct file_operations sysvipc_proc_fops = {
ae781774
MW
982 .open = sysvipc_proc_open,
983 .read = seq_read,
984 .llseek = seq_lseek,
bc1fc6d8 985 .release = sysvipc_proc_release,
ae781774
MW
986};
987#endif /* CONFIG_PROC_FS */