linux/ipc/util.c
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   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 * General sysv ipc locking scheme:
  20 *      rcu_read_lock()
  21 *          obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
  22 *          tree.
  23 *          - perform initial checks (capabilities, auditing and permission,
  24 *            etc).
  25 *          - perform read-only operations, such as STAT, INFO commands.
  26 *            acquire the ipc lock (kern_ipc_perm.lock) through
  27 *            ipc_lock_object()
  28 *              - perform data updates, such as SET, RMID commands and
  29 *                mechanism-specific operations (semop/semtimedop,
  30 *                msgsnd/msgrcv, shmat/shmdt).
  31 *          drop the ipc lock, through ipc_unlock_object().
  32 *      rcu_read_unlock()
  33 *
  34 *  The ids->rwsem must be taken when:
  35 *      - creating, removing and iterating the existing entries in ipc
  36 *        identifier sets.
  37 *      - iterating through files under /proc/sysvipc/
  38 *
  39 *  Note that sems have a special fast path that avoids kern_ipc_perm.lock -
  40 *  see sem_lock().
  41 */
  42
  43#include <linux/mm.h>
  44#include <linux/shm.h>
  45#include <linux/init.h>
  46#include <linux/msg.h>
  47#include <linux/vmalloc.h>
  48#include <linux/slab.h>
  49#include <linux/notifier.h>
  50#include <linux/capability.h>
  51#include <linux/highuid.h>
  52#include <linux/security.h>
  53#include <linux/rcupdate.h>
  54#include <linux/workqueue.h>
  55#include <linux/seq_file.h>
  56#include <linux/proc_fs.h>
  57#include <linux/audit.h>
  58#include <linux/nsproxy.h>
  59#include <linux/rwsem.h>
  60#include <linux/memory.h>
  61#include <linux/ipc_namespace.h>
  62
  63#include <asm/unistd.h>
  64
  65#include "util.h"
  66
  67struct ipc_proc_iface {
  68        const char *path;
  69        const char *header;
  70        int ids;
  71        int (*show)(struct seq_file *, void *);
  72};
  73
  74/**
  75 * ipc_init - initialise ipc subsystem
  76 *
  77 * The various sysv ipc resources (semaphores, messages and shared
  78 * memory) are initialised.
  79 *
  80 * A callback routine is registered into the memory hotplug notifier
  81 * chain: since msgmni scales to lowmem this callback routine will be
  82 * called upon successful memory add / remove to recompute msmgni.
  83 */
  84static int __init ipc_init(void)
  85{
  86        sem_init();
  87        msg_init();
  88        shm_init();
  89        return 0;
  90}
  91device_initcall(ipc_init);
  92
  93/**
  94 * ipc_init_ids - initialise ipc identifiers
  95 * @ids: ipc identifier set
  96 *
  97 * Set up the sequence range to use for the ipc identifier range (limited
  98 * below IPCMNI) then initialise the ids idr.
  99 */
 100void ipc_init_ids(struct ipc_ids *ids)
 101{
 102        ids->in_use = 0;
 103        ids->seq = 0;
 104        ids->next_id = -1;
 105        init_rwsem(&ids->rwsem);
 106        idr_init(&ids->ipcs_idr);
 107}
 108
 109#ifdef CONFIG_PROC_FS
 110static const struct file_operations sysvipc_proc_fops;
 111/**
 112 * ipc_init_proc_interface -  create a proc interface for sysipc types using a seq_file interface.
 113 * @path: Path in procfs
 114 * @header: Banner to be printed at the beginning of the file.
 115 * @ids: ipc id table to iterate.
 116 * @show: show routine.
 117 */
 118void __init ipc_init_proc_interface(const char *path, const char *header,
 119                int ids, int (*show)(struct seq_file *, void *))
 120{
 121        struct proc_dir_entry *pde;
 122        struct ipc_proc_iface *iface;
 123
 124        iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 125        if (!iface)
 126                return;
 127        iface->path     = path;
 128        iface->header   = header;
 129        iface->ids      = ids;
 130        iface->show     = show;
 131
 132        pde = proc_create_data(path,
 133                               S_IRUGO,        /* world readable */
 134                               NULL,           /* parent dir */
 135                               &sysvipc_proc_fops,
 136                               iface);
 137        if (!pde)
 138                kfree(iface);
 139}
 140#endif
 141
 142/**
 143 * ipc_findkey  - find a key in an ipc identifier set
 144 * @ids: ipc identifier set
 145 * @key: key to find
 146 *
 147 * Returns the locked pointer to the ipc structure if found or NULL
 148 * otherwise. If key is found ipc points to the owning ipc structure
 149 *
 150 * Called with ipc_ids.rwsem held.
 151 */
 152static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 153{
 154        struct kern_ipc_perm *ipc;
 155        int next_id;
 156        int total;
 157
 158        for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
 159                ipc = idr_find(&ids->ipcs_idr, next_id);
 160
 161                if (ipc == NULL)
 162                        continue;
 163
 164                if (ipc->key != key) {
 165                        total++;
 166                        continue;
 167                }
 168
 169                rcu_read_lock();
 170                ipc_lock_object(ipc);
 171                return ipc;
 172        }
 173
 174        return NULL;
 175}
 176
 177/**
 178 * ipc_get_maxid - get the last assigned id
 179 * @ids: ipc identifier set
 180 *
 181 * Called with ipc_ids.rwsem held.
 182 */
 183int ipc_get_maxid(struct ipc_ids *ids)
 184{
 185        struct kern_ipc_perm *ipc;
 186        int max_id = -1;
 187        int total, id;
 188
 189        if (ids->in_use == 0)
 190                return -1;
 191
 192        if (ids->in_use == IPCMNI)
 193                return IPCMNI - 1;
 194
 195        /* Look for the last assigned id */
 196        total = 0;
 197        for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
 198                ipc = idr_find(&ids->ipcs_idr, id);
 199                if (ipc != NULL) {
 200                        max_id = id;
 201                        total++;
 202                }
 203        }
 204        return max_id;
 205}
 206
 207/**
 208 * ipc_addid - add an ipc identifier
 209 * @ids: ipc identifier set
 210 * @new: new ipc permission set
 211 * @size: limit for the number of used ids
 212 *
 213 * Add an entry 'new' to the ipc ids idr. The permissions object is
 214 * initialised and the first free entry is set up and the id assigned
 215 * is returned. The 'new' entry is returned in a locked state on success.
 216 * On failure the entry is not locked and a negative err-code is returned.
 217 *
 218 * Called with writer ipc_ids.rwsem held.
 219 */
 220int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int size)
 221{
 222        kuid_t euid;
 223        kgid_t egid;
 224        int id;
 225        int next_id = ids->next_id;
 226
 227        if (size > IPCMNI)
 228                size = IPCMNI;
 229
 230        if (ids->in_use >= size)
 231                return -ENOSPC;
 232
 233        idr_preload(GFP_KERNEL);
 234
 235        spin_lock_init(&new->lock);
 236        new->deleted = false;
 237        rcu_read_lock();
 238        spin_lock(&new->lock);
 239
 240        id = idr_alloc(&ids->ipcs_idr, new,
 241                       (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
 242                       GFP_NOWAIT);
 243        idr_preload_end();
 244        if (id < 0) {
 245                spin_unlock(&new->lock);
 246                rcu_read_unlock();
 247                return id;
 248        }
 249
 250        ids->in_use++;
 251
 252        current_euid_egid(&euid, &egid);
 253        new->cuid = new->uid = euid;
 254        new->gid = new->cgid = egid;
 255
 256        if (next_id < 0) {
 257                new->seq = ids->seq++;
 258                if (ids->seq > IPCID_SEQ_MAX)
 259                        ids->seq = 0;
 260        } else {
 261                new->seq = ipcid_to_seqx(next_id);
 262                ids->next_id = -1;
 263        }
 264
 265        new->id = ipc_buildid(id, new->seq);
 266        return id;
 267}
 268
 269/**
 270 * ipcget_new - create a new ipc object
 271 * @ns: ipc namespace
 272 * @ids: ipc identifier set
 273 * @ops: the actual creation routine to call
 274 * @params: its parameters
 275 *
 276 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
 277 * when the key is IPC_PRIVATE.
 278 */
 279static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 280                const struct ipc_ops *ops, struct ipc_params *params)
 281{
 282        int err;
 283
 284        down_write(&ids->rwsem);
 285        err = ops->getnew(ns, params);
 286        up_write(&ids->rwsem);
 287        return err;
 288}
 289
 290/**
 291 * ipc_check_perms - check security and permissions for an ipc object
 292 * @ns: ipc namespace
 293 * @ipcp: ipc permission set
 294 * @ops: the actual security routine to call
 295 * @params: its parameters
 296 *
 297 * This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 298 * when the key is not IPC_PRIVATE and that key already exists in the
 299 * ds IDR.
 300 *
 301 * On success, the ipc id is returned.
 302 *
 303 * It is called with ipc_ids.rwsem and ipcp->lock held.
 304 */
 305static int ipc_check_perms(struct ipc_namespace *ns,
 306                           struct kern_ipc_perm *ipcp,
 307                           const struct ipc_ops *ops,
 308                           struct ipc_params *params)
 309{
 310        int err;
 311
 312        if (ipcperms(ns, ipcp, params->flg))
 313                err = -EACCES;
 314        else {
 315                err = ops->associate(ipcp, params->flg);
 316                if (!err)
 317                        err = ipcp->id;
 318        }
 319
 320        return err;
 321}
 322
 323/**
 324 * ipcget_public - get an ipc object or create a new one
 325 * @ns: ipc namespace
 326 * @ids: ipc identifier set
 327 * @ops: the actual creation routine to call
 328 * @params: its parameters
 329 *
 330 * This routine is called by sys_msgget, sys_semget() and sys_shmget()
 331 * when the key is not IPC_PRIVATE.
 332 * It adds a new entry if the key is not found and does some permission
 333 * / security checkings if the key is found.
 334 *
 335 * On success, the ipc id is returned.
 336 */
 337static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 338                const struct ipc_ops *ops, struct ipc_params *params)
 339{
 340        struct kern_ipc_perm *ipcp;
 341        int flg = params->flg;
 342        int err;
 343
 344        /*
 345         * Take the lock as a writer since we are potentially going to add
 346         * a new entry + read locks are not "upgradable"
 347         */
 348        down_write(&ids->rwsem);
 349        ipcp = ipc_findkey(ids, params->key);
 350        if (ipcp == NULL) {
 351                /* key not used */
 352                if (!(flg & IPC_CREAT))
 353                        err = -ENOENT;
 354                else
 355                        err = ops->getnew(ns, params);
 356        } else {
 357                /* ipc object has been locked by ipc_findkey() */
 358
 359                if (flg & IPC_CREAT && flg & IPC_EXCL)
 360                        err = -EEXIST;
 361                else {
 362                        err = 0;
 363                        if (ops->more_checks)
 364                                err = ops->more_checks(ipcp, params);
 365                        if (!err)
 366                                /*
 367                                 * ipc_check_perms returns the IPC id on
 368                                 * success
 369                                 */
 370                                err = ipc_check_perms(ns, ipcp, ops, params);
 371                }
 372                ipc_unlock(ipcp);
 373        }
 374        up_write(&ids->rwsem);
 375
 376        return err;
 377}
 378
 379
 380/**
 381 * ipc_rmid - remove an ipc identifier
 382 * @ids: ipc identifier set
 383 * @ipcp: ipc perm structure containing the identifier to remove
 384 *
 385 * ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
 386 * before this function is called, and remain locked on the exit.
 387 */
 388void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 389{
 390        int lid = ipcid_to_idx(ipcp->id);
 391
 392        idr_remove(&ids->ipcs_idr, lid);
 393        ids->in_use--;
 394        ipcp->deleted = true;
 395}
 396
 397/**
 398 * ipc_alloc -  allocate ipc space
 399 * @size: size desired
 400 *
 401 * Allocate memory from the appropriate pools and return a pointer to it.
 402 * NULL is returned if the allocation fails
 403 */
 404void *ipc_alloc(int size)
 405{
 406        void *out;
 407        if (size > PAGE_SIZE)
 408                out = vmalloc(size);
 409        else
 410                out = kmalloc(size, GFP_KERNEL);
 411        return out;
 412}
 413
 414/**
 415 * ipc_free - free ipc space
 416 * @ptr: pointer returned by ipc_alloc
 417 * @size: size of block
 418 *
 419 * Free a block created with ipc_alloc(). The caller must know the size
 420 * used in the allocation call.
 421 */
 422void ipc_free(void *ptr, int size)
 423{
 424        if (size > PAGE_SIZE)
 425                vfree(ptr);
 426        else
 427                kfree(ptr);
 428}
 429
 430/**
 431 * ipc_rcu_alloc - allocate ipc and rcu space
 432 * @size: size desired
 433 *
 434 * Allocate memory for the rcu header structure +  the object.
 435 * Returns the pointer to the object or NULL upon failure.
 436 */
 437void *ipc_rcu_alloc(int size)
 438{
 439        /*
 440         * We prepend the allocation with the rcu struct
 441         */
 442        struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
 443        if (unlikely(!out))
 444                return NULL;
 445        atomic_set(&out->refcount, 1);
 446        return out + 1;
 447}
 448
 449int ipc_rcu_getref(void *ptr)
 450{
 451        struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 452
 453        return atomic_inc_not_zero(&p->refcount);
 454}
 455
 456void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
 457{
 458        struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 459
 460        if (!atomic_dec_and_test(&p->refcount))
 461                return;
 462
 463        call_rcu(&p->rcu, func);
 464}
 465
 466void ipc_rcu_free(struct rcu_head *head)
 467{
 468        struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
 469
 470        if (is_vmalloc_addr(p))
 471                vfree(p);
 472        else
 473                kfree(p);
 474}
 475
 476/**
 477 * ipcperms - check ipc permissions
 478 * @ns: ipc namespace
 479 * @ipcp: ipc permission set
 480 * @flag: desired permission set
 481 *
 482 * Check user, group, other permissions for access
 483 * to ipc resources. return 0 if allowed
 484 *
 485 * @flag will most probably be 0 or S_...UGO from <linux/stat.h>
 486 */
 487int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 488{
 489        kuid_t euid = current_euid();
 490        int requested_mode, granted_mode;
 491
 492        audit_ipc_obj(ipcp);
 493        requested_mode = (flag >> 6) | (flag >> 3) | flag;
 494        granted_mode = ipcp->mode;
 495        if (uid_eq(euid, ipcp->cuid) ||
 496            uid_eq(euid, ipcp->uid))
 497                granted_mode >>= 6;
 498        else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 499                granted_mode >>= 3;
 500        /* is there some bit set in requested_mode but not in granted_mode? */
 501        if ((requested_mode & ~granted_mode & 0007) &&
 502            !ns_capable(ns->user_ns, CAP_IPC_OWNER))
 503                return -1;
 504
 505        return security_ipc_permission(ipcp, flag);
 506}
 507
 508/*
 509 * Functions to convert between the kern_ipc_perm structure and the
 510 * old/new ipc_perm structures
 511 */
 512
 513/**
 514 * kernel_to_ipc64_perm - convert kernel ipc permissions to user
 515 * @in: kernel permissions
 516 * @out: new style ipc permissions
 517 *
 518 * Turn the kernel object @in into a set of permissions descriptions
 519 * for returning to userspace (@out).
 520 */
 521void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
 522{
 523        out->key        = in->key;
 524        out->uid        = from_kuid_munged(current_user_ns(), in->uid);
 525        out->gid        = from_kgid_munged(current_user_ns(), in->gid);
 526        out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
 527        out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
 528        out->mode       = in->mode;
 529        out->seq        = in->seq;
 530}
 531
 532/**
 533 * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
 534 * @in: new style ipc permissions
 535 * @out: old style ipc permissions
 536 *
 537 * Turn the new style permissions object @in into a compatibility
 538 * object and store it into the @out pointer.
 539 */
 540void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
 541{
 542        out->key        = in->key;
 543        SET_UID(out->uid, in->uid);
 544        SET_GID(out->gid, in->gid);
 545        SET_UID(out->cuid, in->cuid);
 546        SET_GID(out->cgid, in->cgid);
 547        out->mode       = in->mode;
 548        out->seq        = in->seq;
 549}
 550
 551/**
 552 * ipc_obtain_object
 553 * @ids: ipc identifier set
 554 * @id: ipc id to look for
 555 *
 556 * Look for an id in the ipc ids idr and return associated ipc object.
 557 *
 558 * Call inside the RCU critical section.
 559 * The ipc object is *not* locked on exit.
 560 */
 561struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
 562{
 563        struct kern_ipc_perm *out;
 564        int lid = ipcid_to_idx(id);
 565
 566        out = idr_find(&ids->ipcs_idr, lid);
 567        if (!out)
 568                return ERR_PTR(-EINVAL);
 569
 570        return out;
 571}
 572
 573/**
 574 * ipc_lock - lock an ipc structure without rwsem held
 575 * @ids: ipc identifier set
 576 * @id: ipc id to look for
 577 *
 578 * Look for an id in the ipc ids idr and lock the associated ipc object.
 579 *
 580 * The ipc object is locked on successful exit.
 581 */
 582struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 583{
 584        struct kern_ipc_perm *out;
 585
 586        rcu_read_lock();
 587        out = ipc_obtain_object(ids, id);
 588        if (IS_ERR(out))
 589                goto err1;
 590
 591        spin_lock(&out->lock);
 592
 593        /* ipc_rmid() may have already freed the ID while ipc_lock
 594         * was spinning: here verify that the structure is still valid
 595         */
 596        if (ipc_valid_object(out))
 597                return out;
 598
 599        spin_unlock(&out->lock);
 600        out = ERR_PTR(-EINVAL);
 601err1:
 602        rcu_read_unlock();
 603        return out;
 604}
 605
 606/**
 607 * ipc_obtain_object_check
 608 * @ids: ipc identifier set
 609 * @id: ipc id to look for
 610 *
 611 * Similar to ipc_obtain_object() but also checks
 612 * the ipc object reference counter.
 613 *
 614 * Call inside the RCU critical section.
 615 * The ipc object is *not* locked on exit.
 616 */
 617struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
 618{
 619        struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
 620
 621        if (IS_ERR(out))
 622                goto out;
 623
 624        if (ipc_checkid(out, id))
 625                return ERR_PTR(-EIDRM);
 626out:
 627        return out;
 628}
 629
 630/**
 631 * ipcget - Common sys_*get() code
 632 * @ns: namespace
 633 * @ids: ipc identifier set
 634 * @ops: operations to be called on ipc object creation, permission checks
 635 *       and further checks
 636 * @params: the parameters needed by the previous operations.
 637 *
 638 * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 639 */
 640int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 641                        const struct ipc_ops *ops, struct ipc_params *params)
 642{
 643        if (params->key == IPC_PRIVATE)
 644                return ipcget_new(ns, ids, ops, params);
 645        else
 646                return ipcget_public(ns, ids, ops, params);
 647}
 648
 649/**
 650 * ipc_update_perm - update the permissions of an ipc object
 651 * @in:  the permission given as input.
 652 * @out: the permission of the ipc to set.
 653 */
 654int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 655{
 656        kuid_t uid = make_kuid(current_user_ns(), in->uid);
 657        kgid_t gid = make_kgid(current_user_ns(), in->gid);
 658        if (!uid_valid(uid) || !gid_valid(gid))
 659                return -EINVAL;
 660
 661        out->uid = uid;
 662        out->gid = gid;
 663        out->mode = (out->mode & ~S_IRWXUGO)
 664                | (in->mode & S_IRWXUGO);
 665
 666        return 0;
 667}
 668
 669/**
 670 * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
 671 * @ns:  ipc namespace
 672 * @ids:  the table of ids where to look for the ipc
 673 * @id:   the id of the ipc to retrieve
 674 * @cmd:  the cmd to check
 675 * @perm: the permission to set
 676 * @extra_perm: one extra permission parameter used by msq
 677 *
 678 * This function does some common audit and permissions check for some IPC_XXX
 679 * cmd and is called from semctl_down, shmctl_down and msgctl_down.
 680 * It must be called without any lock held and
 681 *  - retrieves the ipc with the given id in the given table.
 682 *  - performs some audit and permission check, depending on the given cmd
 683 *  - returns a pointer to the ipc object or otherwise, the corresponding error.
 684 *
 685 * Call holding the both the rwsem and the rcu read lock.
 686 */
 687struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 688                                        struct ipc_ids *ids, int id, int cmd,
 689                                        struct ipc64_perm *perm, int extra_perm)
 690{
 691        kuid_t euid;
 692        int err = -EPERM;
 693        struct kern_ipc_perm *ipcp;
 694
 695        ipcp = ipc_obtain_object_check(ids, id);
 696        if (IS_ERR(ipcp)) {
 697                err = PTR_ERR(ipcp);
 698                goto err;
 699        }
 700
 701        audit_ipc_obj(ipcp);
 702        if (cmd == IPC_SET)
 703                audit_ipc_set_perm(extra_perm, perm->uid,
 704                                   perm->gid, perm->mode);
 705
 706        euid = current_euid();
 707        if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
 708            ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 709                return ipcp; /* successful lookup */
 710err:
 711        return ERR_PTR(err);
 712}
 713
 714#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 715
 716
 717/**
 718 * ipc_parse_version - ipc call version
 719 * @cmd: pointer to command
 720 *
 721 * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 722 * The @cmd value is turned from an encoding command and version into
 723 * just the command code.
 724 */
 725int ipc_parse_version(int *cmd)
 726{
 727        if (*cmd & IPC_64) {
 728                *cmd ^= IPC_64;
 729                return IPC_64;
 730        } else {
 731                return IPC_OLD;
 732        }
 733}
 734
 735#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
 736
 737#ifdef CONFIG_PROC_FS
 738struct ipc_proc_iter {
 739        struct ipc_namespace *ns;
 740        struct ipc_proc_iface *iface;
 741};
 742
 743/*
 744 * This routine locks the ipc structure found at least at position pos.
 745 */
 746static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 747                                              loff_t *new_pos)
 748{
 749        struct kern_ipc_perm *ipc;
 750        int total, id;
 751
 752        total = 0;
 753        for (id = 0; id < pos && total < ids->in_use; id++) {
 754                ipc = idr_find(&ids->ipcs_idr, id);
 755                if (ipc != NULL)
 756                        total++;
 757        }
 758
 759        if (total >= ids->in_use)
 760                return NULL;
 761
 762        for (; pos < IPCMNI; pos++) {
 763                ipc = idr_find(&ids->ipcs_idr, pos);
 764                if (ipc != NULL) {
 765                        *new_pos = pos + 1;
 766                        rcu_read_lock();
 767                        ipc_lock_object(ipc);
 768                        return ipc;
 769                }
 770        }
 771
 772        /* Out of range - return NULL to terminate iteration */
 773        return NULL;
 774}
 775
 776static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 777{
 778        struct ipc_proc_iter *iter = s->private;
 779        struct ipc_proc_iface *iface = iter->iface;
 780        struct kern_ipc_perm *ipc = it;
 781
 782        /* If we had an ipc id locked before, unlock it */
 783        if (ipc && ipc != SEQ_START_TOKEN)
 784                ipc_unlock(ipc);
 785
 786        return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 787}
 788
 789/*
 790 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 791 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 792 */
 793static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 794{
 795        struct ipc_proc_iter *iter = s->private;
 796        struct ipc_proc_iface *iface = iter->iface;
 797        struct ipc_ids *ids;
 798
 799        ids = &iter->ns->ids[iface->ids];
 800
 801        /*
 802         * Take the lock - this will be released by the corresponding
 803         * call to stop().
 804         */
 805        down_read(&ids->rwsem);
 806
 807        /* pos < 0 is invalid */
 808        if (*pos < 0)
 809                return NULL;
 810
 811        /* pos == 0 means header */
 812        if (*pos == 0)
 813                return SEQ_START_TOKEN;
 814
 815        /* Find the (pos-1)th ipc */
 816        return sysvipc_find_ipc(ids, *pos - 1, pos);
 817}
 818
 819static void sysvipc_proc_stop(struct seq_file *s, void *it)
 820{
 821        struct kern_ipc_perm *ipc = it;
 822        struct ipc_proc_iter *iter = s->private;
 823        struct ipc_proc_iface *iface = iter->iface;
 824        struct ipc_ids *ids;
 825
 826        /* If we had a locked structure, release it */
 827        if (ipc && ipc != SEQ_START_TOKEN)
 828                ipc_unlock(ipc);
 829
 830        ids = &iter->ns->ids[iface->ids];
 831        /* Release the lock we took in start() */
 832        up_read(&ids->rwsem);
 833}
 834
 835static int sysvipc_proc_show(struct seq_file *s, void *it)
 836{
 837        struct ipc_proc_iter *iter = s->private;
 838        struct ipc_proc_iface *iface = iter->iface;
 839
 840        if (it == SEQ_START_TOKEN)
 841                return seq_puts(s, iface->header);
 842
 843        return iface->show(s, it);
 844}
 845
 846static const struct seq_operations sysvipc_proc_seqops = {
 847        .start = sysvipc_proc_start,
 848        .stop  = sysvipc_proc_stop,
 849        .next  = sysvipc_proc_next,
 850        .show  = sysvipc_proc_show,
 851};
 852
 853static int sysvipc_proc_open(struct inode *inode, struct file *file)
 854{
 855        struct ipc_proc_iter *iter;
 856
 857        iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
 858        if (!iter)
 859                return -ENOMEM;
 860
 861        iter->iface = PDE_DATA(inode);
 862        iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 863
 864        return 0;
 865}
 866
 867static int sysvipc_proc_release(struct inode *inode, struct file *file)
 868{
 869        struct seq_file *seq = file->private_data;
 870        struct ipc_proc_iter *iter = seq->private;
 871        put_ipc_ns(iter->ns);
 872        return seq_release_private(inode, file);
 873}
 874
 875static const struct file_operations sysvipc_proc_fops = {
 876        .open    = sysvipc_proc_open,
 877        .read    = seq_read,
 878        .llseek  = seq_lseek,
 879        .release = sysvipc_proc_release,
 880};
 881#endif /* CONFIG_PROC_FS */
 882
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