ipc/util.c

   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  *  when doing ipc id lookups, take the ids->rwsem
  21  *      rcu_read_lock()
  22  *          obtain the ipc object (kern_ipc_perm)
  23  *          perform security, capabilities, auditing and permission checks, etc.
  24  *          acquire the ipc lock (kern_ipc_perm.lock) throught ipc_lock_object()
  25  *             perform data updates (ie: SET, RMID, LOCK/UNLOCK commands)
  26  */
  27
  28 #include <linux/mm.h>
  29 #include <linux/shm.h>
  30 #include <linux/init.h>
  31 #include <linux/msg.h>
  32 #include <linux/vmalloc.h>
  33 #include <linux/slab.h>
  34 #include <linux/notifier.h>
  35 #include <linux/capability.h>
  36 #include <linux/highuid.h>
  37 #include <linux/security.h>
  38 #include <linux/rcupdate.h>
  39 #include <linux/workqueue.h>
  40 #include <linux/seq_file.h>
  41 #include <linux/proc_fs.h>
  42 #include <linux/audit.h>
  43 #include <linux/nsproxy.h>
  44 #include <linux/rwsem.h>
  45 #include <linux/memory.h>
  46 #include <linux/ipc_namespace.h>
  47
  48 #include <asm/unistd.h>
  49
  50 #include "util.h"
  51
  52 struct ipc_proc_iface {
  53         const char *path;
  54         const char *header;
  55         int ids;
  56         int (*show)(struct seq_file *, void *);
  57 };
  58
  59 static void ipc_memory_notifier(struct work_struct *work)
  60 {
  61         ipcns_notify(IPCNS_MEMCHANGED);
  62 }
  63
  64 static int ipc_memory_callback(struct notifier_block *self,
  65                                 unsigned long action, void *arg)
  66 {
  67         static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
  68
  69         switch (action) {
  70         case MEM_ONLINE:    /* memory successfully brought online */
  71         case MEM_OFFLINE:   /* or offline: it's time to recompute msgmni */
  72                 /*
  73                  * This is done by invoking the ipcns notifier chain with the
  74                  * IPC_MEMCHANGED event.
  75                  * In order not to keep the lock on the hotplug memory chain
  76                  * for too long, queue a work item that will, when waken up,
  77                  * activate the ipcns notification chain.
  78                  * No need to keep several ipc work items on the queue.
  79                  */
  80                 if (!work_pending(&ipc_memory_wq))
  81                         schedule_work(&ipc_memory_wq);
  82                 break;
  83         case MEM_GOING_ONLINE:
  84         case MEM_GOING_OFFLINE:
  85         case MEM_CANCEL_ONLINE:
  86         case MEM_CANCEL_OFFLINE:
  87         default:
  88                 break;
  89         }
  90
  91         return NOTIFY_OK;
  92 }
  93
  94 static struct notifier_block ipc_memory_nb = {
  95         .notifier_call = ipc_memory_callback,
  96         .priority = IPC_CALLBACK_PRI,
  97 };
  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
 109 static int __init ipc_init(void)
 110 {
 111         sem_init();
 112         msg_init();
 113         shm_init();
 114         register_hotmemory_notifier(&ipc_memory_nb);
 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
 128 void ipc_init_ids(struct ipc_ids *ids)
 129 {
 130         init_rwsem(&ids->rwsem);
 131
 132         ids->in_use = 0;
 133         ids->seq = 0;
 134         ids->next_id = -1;
 135         {
 136                 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
 137                 if (seq_limit > USHRT_MAX)
 138                         ids->seq_max = USHRT_MAX;
 139                  else
 140                         ids->seq_max = seq_limit;
 141         }
 142
 143         idr_init(&ids->ipcs_idr);
 144 }
 145
 146 #ifdef CONFIG_PROC_FS
 147 static const struct file_operations sysvipc_proc_fops;
 148 /**
 149  *      ipc_init_proc_interface -  Create a proc interface for sysipc types using a seq_file interface.
 150  *      @path: Path in procfs
 151  *      @header: Banner to be printed at the beginning of the file.
 152  *      @ids: ipc id table to iterate.
 153  *      @show: show routine.
 154  */
 155 void __init ipc_init_proc_interface(const char *path, const char *header,
 156                 int ids, int (*show)(struct seq_file *, void *))
 157 {
 158         struct proc_dir_entry *pde;
 159         struct ipc_proc_iface *iface;
 160
 161         iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 162         if (!iface)
 163                 return;
 164         iface->path     = path;
 165         iface->header   = header;
 166         iface->ids      = ids;
 167         iface->show     = show;
 168
 169         pde = proc_create_data(path,
 170                                S_IRUGO,        /* world readable */
 171                                NULL,           /* parent dir */
 172                                &sysvipc_proc_fops,
 173                                iface);
 174         if (!pde) {
 175                 kfree(iface);
 176         }
 177 }
 178 #endif
 179
 180 /**
 181  *      ipc_findkey     -       find a key in an ipc identifier set
 182  *      @ids: Identifier set
 183  *      @key: The key to find
 184  *
 185  *      Requires ipc_ids.rwsem locked.
 186  *      Returns the LOCKED pointer to the ipc structure if found or NULL
 187  *      if not.
 188  *      If key is found ipc points to the owning ipc structure
 189  */
 190
 191 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 192 {
 193         struct kern_ipc_perm *ipc;
 194         int next_id;
 195         int total;
 196
 197         for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
 198                 ipc = idr_find(&ids->ipcs_idr, next_id);
 199
 200                 if (ipc == NULL)
 201                         continue;
 202
 203                 if (ipc->key != key) {
 204                         total++;
 205                         continue;
 206                 }
 207
 208                 ipc_lock_by_ptr(ipc);
 209                 return ipc;
 210         }
 211
 212         return NULL;
 213 }
 214
 215 /**
 216  *      ipc_get_maxid   -       get the last assigned id
 217  *      @ids: IPC identifier set
 218  *
 219  *      Called with ipc_ids.rwsem held.
 220  */
 221
 222 int ipc_get_maxid(struct ipc_ids *ids)
 223 {
 224         struct kern_ipc_perm *ipc;
 225         int max_id = -1;
 226         int total, id;
 227
 228         if (ids->in_use == 0)
 229                 return -1;
 230
 231         if (ids->in_use == IPCMNI)
 232                 return IPCMNI - 1;
 233
 234         /* Look for the last assigned id */
 235         total = 0;
 236         for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
 237                 ipc = idr_find(&ids->ipcs_idr, id);
 238                 if (ipc != NULL) {
 239                         max_id = id;
 240                         total++;
 241                 }
 242         }
 243         return max_id;
 244 }
 245
 246 /**
 247  *      ipc_addid       -       add an IPC identifier
 248  *      @ids: IPC identifier set
 249  *      @new: new IPC permission set
 250  *      @size: limit for the number of used ids
 251  *
 252  *      Add an entry 'new' to the IPC ids idr. The permissions object is
 253  *      initialised and the first free entry is set up and the id assigned
 254  *      is returned. The 'new' entry is returned in a locked state on success.
 255  *      On failure the entry is not locked and a negative err-code is returned.
 256  *
 257  *      Called with writer ipc_ids.rwsem held.
 258  */
 259 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 260 {
 261         kuid_t euid;
 262         kgid_t egid;
 263         int id;
 264         int next_id = ids->next_id;
 265
 266         if (size > IPCMNI)
 267                 size = IPCMNI;
 268
 269         if (ids->in_use >= size)
 270                 return -ENOSPC;
 271
 272         idr_preload(GFP_KERNEL);
 273
 274         spin_lock_init(&new->lock);
 275         new->deleted = 0;
 276         rcu_read_lock();
 277         spin_lock(&new->lock);
 278
 279         id = idr_alloc(&ids->ipcs_idr, new,
 280                        (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
 281                        GFP_NOWAIT);
 282         idr_preload_end();
 283         if (id < 0) {
 284                 spin_unlock(&new->lock);
 285                 rcu_read_unlock();
 286                 return id;
 287         }
 288
 289         ids->in_use++;
 290
 291         current_euid_egid(&euid, &egid);
 292         new->cuid = new->uid = euid;
 293         new->gid = new->cgid = egid;
 294
 295         if (next_id < 0) {
 296                 new->seq = ids->seq++;
 297                 if (ids->seq > ids->seq_max)
 298                         ids->seq = 0;
 299         } else {
 300                 new->seq = ipcid_to_seqx(next_id);
 301                 ids->next_id = -1;
 302         }
 303
 304         new->id = ipc_buildid(id, new->seq);
 305         return id;
 306 }
 307
 308 /**
 309  *      ipcget_new      -       create a new ipc object
 310  *      @ns: namespace
 311  *      @ids: IPC identifer set
 312  *      @ops: the actual creation routine to call
 313  *      @params: its parameters
 314  *
 315  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 316  *      when the key is IPC_PRIVATE.
 317  */
 318 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 319                 struct ipc_ops *ops, struct ipc_params *params)
 320 {
 321         int err;
 322
 323         down_write(&ids->rwsem);
 324         err = ops->getnew(ns, params);
 325         up_write(&ids->rwsem);
 326         return err;
 327 }
 328
 329 /**
 330  *      ipc_check_perms -       check security and permissions for an IPC
 331  *      @ns: IPC namespace
 332  *      @ipcp: ipc permission set
 333  *      @ops: the actual security routine to call
 334  *      @params: its parameters
 335  *
 336  *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 337  *      when the key is not IPC_PRIVATE and that key already exists in the
 338  *      ids IDR.
 339  *
 340  *      On success, the IPC id is returned.
 341  *
 342  *      It is called with ipc_ids.rwsem and ipcp->lock held.
 343  */
 344 static int ipc_check_perms(struct ipc_namespace *ns,
 345                            struct kern_ipc_perm *ipcp,
 346                            struct ipc_ops *ops,
 347                            struct ipc_params *params)
 348 {
 349         int err;
 350
 351         if (ipcperms(ns, ipcp, params->flg))
 352                 err = -EACCES;
 353         else {
 354                 err = ops->associate(ipcp, params->flg);
 355                 if (!err)
 356                         err = ipcp->id;
 357         }
 358
 359         return err;
 360 }
 361
 362 /**
 363  *      ipcget_public   -       get an ipc object or create a new one
 364  *      @ns: namespace
 365  *      @ids: IPC identifer set
 366  *      @ops: the actual creation routine to call
 367  *      @params: its parameters
 368  *
 369  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 370  *      when the key is not IPC_PRIVATE.
 371  *      It adds a new entry if the key is not found and does some permission
 372  *      / security checkings if the key is found.
 373  *
 374  *      On success, the ipc id is returned.
 375  */
 376 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 377                 struct ipc_ops *ops, struct ipc_params *params)
 378 {
 379         struct kern_ipc_perm *ipcp;
 380         int flg = params->flg;
 381         int err;
 382
 383         /*
 384          * Take the lock as a writer since we are potentially going to add
 385          * a new entry + read locks are not "upgradable"
 386          */
 387         down_write(&ids->rwsem);
 388         ipcp = ipc_findkey(ids, params->key);
 389         if (ipcp == NULL) {
 390                 /* key not used */
 391                 if (!(flg & IPC_CREAT))
 392                         err = -ENOENT;
 393                 else
 394                         err = ops->getnew(ns, params);
 395         } else {
 396                 /* ipc object has been locked by ipc_findkey() */
 397
 398                 if (flg & IPC_CREAT && flg & IPC_EXCL)
 399                         err = -EEXIST;
 400                 else {
 401                         err = 0;
 402                         if (ops->more_checks)
 403                                 err = ops->more_checks(ipcp, params);
 404                         if (!err)
 405                                 /*
 406                                  * ipc_check_perms returns the IPC id on
 407                                  * success
 408                                  */
 409                                 err = ipc_check_perms(ns, ipcp, ops, params);
 410                 }
 411                 ipc_unlock(ipcp);
 412         }
 413         up_write(&ids->rwsem);
 414
 415         return err;
 416 }
 417
 418
 419 /**
 420  *      ipc_rmid        -       remove an IPC identifier
 421  *      @ids: IPC identifier set
 422  *      @ipcp: ipc perm structure containing the identifier to remove
 423  *
 424  *      ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
 425  *      before this function is called, and remain locked on the exit.
 426  */
 427
 428 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 429 {
 430         int lid = ipcid_to_idx(ipcp->id);
 431
 432         idr_remove(&ids->ipcs_idr, lid);
 433
 434         ids->in_use--;
 435
 436         ipcp->deleted = 1;
 437
 438         return;
 439 }
 440
 441 /**
 442  *      ipc_alloc       -       allocate ipc space
 443  *      @size: size desired
 444  *
 445  *      Allocate memory from the appropriate pools and return a pointer to it.
 446  *      NULL is returned if the allocation fails
 447  */
 448
 449 void *ipc_alloc(int size)
 450 {
 451         void *out;
 452         if(size > PAGE_SIZE)
 453                 out = vmalloc(size);
 454         else
 455                 out = kmalloc(size, GFP_KERNEL);
 456         return out;
 457 }
 458
 459 /**
 460  *      ipc_free        -       free ipc space
 461  *      @ptr: pointer returned by ipc_alloc
 462  *      @size: size of block
 463  *
 464  *      Free a block created with ipc_alloc(). The caller must know the size
 465  *      used in the allocation call.
 466  */
 467
 468 void ipc_free(void* ptr, int size)
 469 {
 470         if(size > PAGE_SIZE)
 471                 vfree(ptr);
 472         else
 473                 kfree(ptr);
 474 }
 475
 476 struct ipc_rcu {
 477         struct rcu_head rcu;
 478         atomic_t refcount;
 479 } ____cacheline_aligned_in_smp;
 480
 481 /**
 482  *      ipc_rcu_alloc   -       allocate ipc and rcu space
 483  *      @size: size desired
 484  *
 485  *      Allocate memory for the rcu header structure +  the object.
 486  *      Returns the pointer to the object or NULL upon failure.
 487  */
 488 void *ipc_rcu_alloc(int size)
 489 {
 490         /*
 491          * We prepend the allocation with the rcu struct
 492          */
 493         struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
 494         if (unlikely(!out))
 495                 return NULL;
 496         atomic_set(&out->refcount, 1);
 497         return out + 1;
 498 }
 499
 500 int ipc_rcu_getref(void *ptr)
 501 {
 502         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 503
 504         return atomic_inc_not_zero(&p->refcount);
 505 }
 506
 507 /**
 508  * ipc_schedule_free - free ipc + rcu space
 509  * @head: RCU callback structure for queued work
 510  */
 511 static void ipc_schedule_free(struct rcu_head *head)
 512 {
 513         vfree(container_of(head, struct ipc_rcu, rcu));
 514 }
 515
 516 void ipc_rcu_putref(void *ptr)
 517 {
 518         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 519
 520         if (!atomic_dec_and_test(&p->refcount))
 521                 return;
 522
 523         if (is_vmalloc_addr(ptr)) {
 524                 call_rcu(&p->rcu, ipc_schedule_free);
 525         } else {
 526                 kfree_rcu(p, rcu);
 527         }
 528 }
 529
 530 /**
 531  *      ipcperms        -       check IPC permissions
 532  *      @ns: IPC namespace
 533  *      @ipcp: IPC permission set
 534  *      @flag: desired permission set.
 535  *
 536  *      Check user, group, other permissions for access
 537  *      to ipc resources. return 0 if allowed
 538  *
 539  *      @flag will most probably be 0 or S_...UGO from <linux/stat.h>
 540  */
 541
 542 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 543 {
 544         kuid_t euid = current_euid();
 545         int requested_mode, granted_mode;
 546
 547         audit_ipc_obj(ipcp);
 548         requested_mode = (flag >> 6) | (flag >> 3) | flag;
 549         granted_mode = ipcp->mode;
 550         if (uid_eq(euid, ipcp->cuid) ||
 551             uid_eq(euid, ipcp->uid))
 552                 granted_mode >>= 6;
 553         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 554                 granted_mode >>= 3;
 555         /* is there some bit set in requested_mode but not in granted_mode? */
 556         if ((requested_mode & ~granted_mode & 0007) &&
 557             !ns_capable(ns->user_ns, CAP_IPC_OWNER))
 558                 return -1;
 559
 560         return security_ipc_permission(ipcp, flag);
 561 }
 562
 563 /*
 564  * Functions to convert between the kern_ipc_perm structure and the
 565  * old/new ipc_perm structures
 566  */
 567
 568 /**
 569  *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
 570  *      @in: kernel permissions
 571  *      @out: new style IPC permissions
 572  *
 573  *      Turn the kernel object @in into a set of permissions descriptions
 574  *      for returning to userspace (@out).
 575  */
 576
 577
 578 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
 579 {
 580         out->key        = in->key;
 581         out->uid        = from_kuid_munged(current_user_ns(), in->uid);
 582         out->gid        = from_kgid_munged(current_user_ns(), in->gid);
 583         out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
 584         out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
 585         out->mode       = in->mode;
 586         out->seq        = in->seq;
 587 }
 588
 589 /**
 590  *      ipc64_perm_to_ipc_perm  -       convert new ipc permissions to old
 591  *      @in: new style IPC permissions
 592  *      @out: old style IPC permissions
 593  *
 594  *      Turn the new style permissions object @in into a compatibility
 595  *      object and store it into the @out pointer.
 596  */
 597
 598 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
 599 {
 600         out->key        = in->key;
 601         SET_UID(out->uid, in->uid);
 602         SET_GID(out->gid, in->gid);
 603         SET_UID(out->cuid, in->cuid);
 604         SET_GID(out->cgid, in->cgid);
 605         out->mode       = in->mode;
 606         out->seq        = in->seq;
 607 }
 608
 609 /**
 610  * ipc_obtain_object
 611  * @ids: ipc identifier set
 612  * @id: ipc id to look for
 613  *
 614  * Look for an id in the ipc ids idr and return associated ipc object.
 615  *
 616  * Call inside the RCU critical section.
 617  * The ipc object is *not* locked on exit.
 618  */
 619 struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
 620 {
 621         struct kern_ipc_perm *out;
 622         int lid = ipcid_to_idx(id);
 623
 624         out = idr_find(&ids->ipcs_idr, lid);
 625         if (!out)
 626                 return ERR_PTR(-EINVAL);
 627
 628         return out;
 629 }
 630
 631 /**
 632  * ipc_lock - Lock an ipc structure without rwsem held
 633  * @ids: IPC identifier set
 634  * @id: ipc id to look for
 635  *
 636  * Look for an id in the ipc ids idr and lock the associated ipc object.
 637  *
 638  * The ipc object is locked on successful exit.
 639  */
 640 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 641 {
 642         struct kern_ipc_perm *out;
 643
 644         rcu_read_lock();
 645         out = ipc_obtain_object(ids, id);
 646         if (IS_ERR(out))
 647                 goto err1;
 648
 649         spin_lock(&out->lock);
 650
 651         /* ipc_rmid() may have already freed the ID while ipc_lock
 652          * was spinning: here verify that the structure is still valid
 653          */
 654         if (!out->deleted)
 655                 return out;
 656
 657         spin_unlock(&out->lock);
 658         out = ERR_PTR(-EINVAL);
 659 err1:
 660         rcu_read_unlock();
 661         return out;
 662 }
 663
 664 /**
 665  * ipc_obtain_object_check
 666  * @ids: ipc identifier set
 667  * @id: ipc id to look for
 668  *
 669  * Similar to ipc_obtain_object() but also checks
 670  * the ipc object reference counter.
 671  *
 672  * Call inside the RCU critical section.
 673  * The ipc object is *not* locked on exit.
 674  */
 675 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
 676 {
 677         struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
 678
 679         if (IS_ERR(out))
 680                 goto out;
 681
 682         if (ipc_checkid(out, id))
 683                 return ERR_PTR(-EIDRM);
 684 out:
 685         return out;
 686 }
 687
 688 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
 689 {
 690         struct kern_ipc_perm *out;
 691
 692         out = ipc_lock(ids, id);
 693         if (IS_ERR(out))
 694                 return out;
 695
 696         if (ipc_checkid(out, id)) {
 697                 ipc_unlock(out);
 698                 return ERR_PTR(-EIDRM);
 699         }
 700
 701         return out;
 702 }
 703
 704 /**
 705  * ipcget - Common sys_*get() code
 706  * @ns : namsepace
 707  * @ids : IPC identifier set
 708  * @ops : operations to be called on ipc object creation, permission checks
 709  *        and further checks
 710  * @params : the parameters needed by the previous operations.
 711  *
 712  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 713  */
 714 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 715                         struct ipc_ops *ops, struct ipc_params *params)
 716 {
 717         if (params->key == IPC_PRIVATE)
 718                 return ipcget_new(ns, ids, ops, params);
 719         else
 720                 return ipcget_public(ns, ids, ops, params);
 721 }
 722
 723 /**
 724  * ipc_update_perm - update the permissions of an IPC.
 725  * @in:  the permission given as input.
 726  * @out: the permission of the ipc to set.
 727  */
 728 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 729 {
 730         kuid_t uid = make_kuid(current_user_ns(), in->uid);
 731         kgid_t gid = make_kgid(current_user_ns(), in->gid);
 732         if (!uid_valid(uid) || !gid_valid(gid))
 733                 return -EINVAL;
 734
 735         out->uid = uid;
 736         out->gid = gid;
 737         out->mode = (out->mode & ~S_IRWXUGO)
 738                 | (in->mode & S_IRWXUGO);
 739
 740         return 0;
 741 }
 742
 743 /**
 744  * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
 745  * @ns:  the ipc namespace
 746  * @ids:  the table of ids where to look for the ipc
 747  * @id:   the id of the ipc to retrieve
 748  * @cmd:  the cmd to check
 749  * @perm: the permission to set
 750  * @extra_perm: one extra permission parameter used by msq
 751  *
 752  * This function does some common audit and permissions check for some IPC_XXX
 753  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
 754  * It must be called without any lock held and
 755  *  - retrieves the ipc with the given id in the given table.
 756  *  - performs some audit and permission check, depending on the given cmd
 757  *  - returns a pointer to the ipc object or otherwise, the corresponding error.
 758  *
 759  * Call holding the both the rwsem and the rcu read lock.
 760  */
 761 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 762                                         struct ipc_ids *ids, int id, int cmd,
 763                                         struct ipc64_perm *perm, int extra_perm)
 764 {
 765         kuid_t euid;
 766         int err = -EPERM;
 767         struct kern_ipc_perm *ipcp;
 768
 769         ipcp = ipc_obtain_object_check(ids, id);
 770         if (IS_ERR(ipcp)) {
 771                 err = PTR_ERR(ipcp);
 772                 goto err;
 773         }
 774
 775         audit_ipc_obj(ipcp);
 776         if (cmd == IPC_SET)
 777                 audit_ipc_set_perm(extra_perm, perm->uid,
 778                                    perm->gid, perm->mode);
 779
 780         euid = current_euid();
 781         if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
 782             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 783                 return ipcp; /* successful lookup */
 784 err:
 785         return ERR_PTR(err);
 786 }
 787
 788 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 789
 790
 791 /**
 792  *      ipc_parse_version       -       IPC call version
 793  *      @cmd: pointer to command
 794  *
 795  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 796  *      The @cmd value is turned from an encoding command and version into
 797  *      just the command code.
 798  */
 799
 800 int ipc_parse_version (int *cmd)
 801 {
 802         if (*cmd & IPC_64) {
 803                 *cmd ^= IPC_64;
 804                 return IPC_64;
 805         } else {
 806                 return IPC_OLD;
 807         }
 808 }
 809
 810 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
 811
 812 #ifdef CONFIG_PROC_FS
 813 struct ipc_proc_iter {
 814         struct ipc_namespace *ns;
 815         struct ipc_proc_iface *iface;
 816 };
 817
 818 /*
 819  * This routine locks the ipc structure found at least at position pos.
 820  */
 821 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 822                                               loff_t *new_pos)
 823 {
 824         struct kern_ipc_perm *ipc;
 825         int total, id;
 826
 827         total = 0;
 828         for (id = 0; id < pos && total < ids->in_use; id++) {
 829                 ipc = idr_find(&ids->ipcs_idr, id);
 830                 if (ipc != NULL)
 831                         total++;
 832         }
 833
 834         if (total >= ids->in_use)
 835                 return NULL;
 836
 837         for ( ; pos < IPCMNI; pos++) {
 838                 ipc = idr_find(&ids->ipcs_idr, pos);
 839                 if (ipc != NULL) {
 840                         *new_pos = pos + 1;
 841                         ipc_lock_by_ptr(ipc);
 842                         return ipc;
 843                 }
 844         }
 845
 846         /* Out of range - return NULL to terminate iteration */
 847         return NULL;
 848 }
 849
 850 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 851 {
 852         struct ipc_proc_iter *iter = s->private;
 853         struct ipc_proc_iface *iface = iter->iface;
 854         struct kern_ipc_perm *ipc = it;
 855
 856         /* If we had an ipc id locked before, unlock it */
 857         if (ipc && ipc != SEQ_START_TOKEN)
 858                 ipc_unlock(ipc);
 859
 860         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 861 }
 862
 863 /*
 864  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 865  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 866  */
 867 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 868 {
 869         struct ipc_proc_iter *iter = s->private;
 870         struct ipc_proc_iface *iface = iter->iface;
 871         struct ipc_ids *ids;
 872
 873         ids = &iter->ns->ids[iface->ids];
 874
 875         /*
 876          * Take the lock - this will be released by the corresponding
 877          * call to stop().
 878          */
 879         down_read(&ids->rwsem);
 880
 881         /* pos < 0 is invalid */
 882         if (*pos < 0)
 883                 return NULL;
 884
 885         /* pos == 0 means header */
 886         if (*pos == 0)
 887                 return SEQ_START_TOKEN;
 888
 889         /* Find the (pos-1)th ipc */
 890         return sysvipc_find_ipc(ids, *pos - 1, pos);
 891 }
 892
 893 static void sysvipc_proc_stop(struct seq_file *s, void *it)
 894 {
 895         struct kern_ipc_perm *ipc = it;
 896         struct ipc_proc_iter *iter = s->private;
 897         struct ipc_proc_iface *iface = iter->iface;
 898         struct ipc_ids *ids;
 899
 900         /* If we had a locked structure, release it */
 901         if (ipc && ipc != SEQ_START_TOKEN)
 902                 ipc_unlock(ipc);
 903
 904         ids = &iter->ns->ids[iface->ids];
 905         /* Release the lock we took in start() */
 906         up_read(&ids->rwsem);
 907 }
 908
 909 static int sysvipc_proc_show(struct seq_file *s, void *it)
 910 {
 911         struct ipc_proc_iter *iter = s->private;
 912         struct ipc_proc_iface *iface = iter->iface;
 913
 914         if (it == SEQ_START_TOKEN)
 915                 return seq_puts(s, iface->header);
 916
 917         return iface->show(s, it);
 918 }
 919
 920 static const struct seq_operations sysvipc_proc_seqops = {
 921         .start = sysvipc_proc_start,
 922         .stop  = sysvipc_proc_stop,
 923         .next  = sysvipc_proc_next,
 924         .show  = sysvipc_proc_show,
 925 };
 926
 927 static int sysvipc_proc_open(struct inode *inode, struct file *file)
 928 {
 929         int ret;
 930         struct seq_file *seq;
 931         struct ipc_proc_iter *iter;
 932
 933         ret = -ENOMEM;
 934         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 935         if (!iter)
 936                 goto out;
 937
 938         ret = seq_open(file, &sysvipc_proc_seqops);
 939         if (ret)
 940                 goto out_kfree;
 941
 942         seq = file->private_data;
 943         seq->private = iter;
 944
 945         iter->iface = PDE_DATA(inode);
 946         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 947 out:
 948         return ret;
 949 out_kfree:
 950         kfree(iter);
 951         goto out;
 952 }
 953
 954 static int sysvipc_proc_release(struct inode *inode, struct file *file)
 955 {
 956         struct seq_file *seq = file->private_data;
 957         struct ipc_proc_iter *iter = seq->private;
 958         put_ipc_ns(iter->ns);
 959         return seq_release_private(inode, file);
 960 }
 961
 962 static const struct file_operations sysvipc_proc_fops = {
 963         .open    = sysvipc_proc_open,
 964         .read    = seq_read,
 965         .llseek  = seq_lseek,
 966         .release = sysvipc_proc_release,
 967 };
 968 #endif /* CONFIG_PROC_FS */