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