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
  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
  43struct ipc_proc_iface {
  44        const char *path;
  45        const char *header;
  46        int ids;
  47        int (*show)(struct seq_file *, void *);
  48};
  49
  50struct ipc_namespace init_ipc_ns = {
  51        .kref = {
  52                .refcount       = ATOMIC_INIT(2),
  53        },
  54};
  55
  56atomic_t nr_ipc_ns = ATOMIC_INIT(1);
  57
  58
  59#ifdef CONFIG_MEMORY_HOTPLUG
  60
  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
  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.
  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 
 109static 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 
 128void 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
 146static 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 */
 154void __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 
 190static 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
 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;
 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 
 259int 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 */
 307static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 308                struct ipc_ops *ops, struct ipc_params *params)
 309{
 310        int err;
 311retry:
 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 */
 341static 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 */
 371static 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;
 377retry:
 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 
 430void 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 
 451void* 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
 470void 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 */
 488struct ipc_rcu_hdr
 489{
 490        int refcount;
 491        int is_vmalloc;
 492        void *data[0];
 493};
 494
 495
 496struct 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
 503struct 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
 515static 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 
 532void* 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
 558void ipc_rcu_getref(void *ptr)
 559{
 560        container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
 561}
 562
 563static 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 */
 575static 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 */
 594static 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
 601void 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 
 624int 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
 660void 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 
 680void 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
 701struct 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
 727struct 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 */
 753int 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 */
 767void 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 */
 791struct 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);
 817out_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 
 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 */
 845
 846#ifdef CONFIG_PROC_FS
 847struct 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 */
 855static 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
 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
 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 */
 901static 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
 927static 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
 943static 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
 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
 961static 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);
 981out:
 982        return ret;
 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);
 994}
 995
 996static 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