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
  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/ipc_namespace.h>
  37
  38 #include <asm/unistd.h>
  39
  40 #include "util.h"
  41
  42 struct ipc_proc_iface {
  43         const char *path;
  44         const char *header;
  45         int ids;
  46         int (*show)(struct seq_file *, void *);
  47 };
  48
  49 struct ipc_namespace init_ipc_ns = {
  50         .kref = {
  51                 .refcount       = ATOMIC_INIT(2),
  52         },
  53 };
  54
  55 /**
  56  *      ipc_init        -       initialise IPC subsystem
  57  *
  58  *      The various system5 IPC resources (semaphores, messages and shared
  59  *      memory) are initialised
  60  */
  61
  62 static int __init ipc_init(void)
  63 {
  64         sem_init();
  65         msg_init();
  66         shm_init();
  67         return 0;
  68 }
  69 __initcall(ipc_init);
  70
  71 /**
  72  *      ipc_init_ids            -       initialise IPC identifiers
  73  *      @ids: Identifier set
  74  *
  75  *      Set up the sequence range to use for the ipc identifier range (limited
  76  *      below IPCMNI) then initialise the ids idr.
  77  */
  78
  79 void ipc_init_ids(struct ipc_ids *ids)
  80 {
  81         init_rwsem(&ids->rw_mutex);
  82
  83         ids->in_use = 0;
  84         ids->seq = 0;
  85         {
  86                 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
  87                 if(seq_limit > USHRT_MAX)
  88                         ids->seq_max = USHRT_MAX;
  89                  else
  90                         ids->seq_max = seq_limit;
  91         }
  92
  93         idr_init(&ids->ipcs_idr);
  94 }
  95
  96 #ifdef CONFIG_PROC_FS
  97 static const struct file_operations sysvipc_proc_fops;
  98 /**
  99  *      ipc_init_proc_interface -  Create a proc interface for sysipc types using a seq_file interface.
 100  *      @path: Path in procfs
 101  *      @header: Banner to be printed at the beginning of the file.
 102  *      @ids: ipc id table to iterate.
 103  *      @show: show routine.
 104  */
 105 void __init ipc_init_proc_interface(const char *path, const char *header,
 106                 int ids, int (*show)(struct seq_file *, void *))
 107 {
 108         struct proc_dir_entry *pde;
 109         struct ipc_proc_iface *iface;
 110
 111         iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 112         if (!iface)
 113                 return;
 114         iface->path     = path;
 115         iface->header   = header;
 116         iface->ids      = ids;
 117         iface->show     = show;
 118
 119         pde = create_proc_entry(path,
 120                                 S_IRUGO,        /* world readable */
 121                                 NULL            /* parent dir */);
 122         if (pde) {
 123                 pde->data = iface;
 124                 pde->proc_fops = &sysvipc_proc_fops;
 125         } else {
 126                 kfree(iface);
 127         }
 128 }
 129 #endif
 130
 131 /**
 132  *      ipc_findkey     -       find a key in an ipc identifier set
 133  *      @ids: Identifier set
 134  *      @key: The key to find
 135  *
 136  *      Requires ipc_ids.rw_mutex locked.
 137  *      Returns the LOCKED pointer to the ipc structure if found or NULL
 138  *      if not.
 139  *      If key is found ipc points to the owning ipc structure
 140  */
 141
 142 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 143 {
 144         struct kern_ipc_perm *ipc;
 145         int next_id;
 146         int total;
 147
 148         for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
 149                 ipc = idr_find(&ids->ipcs_idr, next_id);
 150
 151                 if (ipc == NULL)
 152                         continue;
 153
 154                 if (ipc->key != key) {
 155                         total++;
 156                         continue;
 157                 }
 158
 159                 ipc_lock_by_ptr(ipc);
 160                 return ipc;
 161         }
 162
 163         return NULL;
 164 }
 165
 166 /**
 167  *      ipc_get_maxid   -       get the last assigned id
 168  *      @ids: IPC identifier set
 169  *
 170  *      Called with ipc_ids.rw_mutex held.
 171  */
 172
 173 int ipc_get_maxid(struct ipc_ids *ids)
 174 {
 175         struct kern_ipc_perm *ipc;
 176         int max_id = -1;
 177         int total, id;
 178
 179         if (ids->in_use == 0)
 180                 return -1;
 181
 182         if (ids->in_use == IPCMNI)
 183                 return IPCMNI - 1;
 184
 185         /* Look for the last assigned id */
 186         total = 0;
 187         for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
 188                 ipc = idr_find(&ids->ipcs_idr, id);
 189                 if (ipc != NULL) {
 190                         max_id = id;
 191                         total++;
 192                 }
 193         }
 194         return max_id;
 195 }
 196
 197 /**
 198  *      ipc_addid       -       add an IPC identifier
 199  *      @ids: IPC identifier set
 200  *      @new: new IPC permission set
 201  *      @size: limit for the number of used ids
 202  *
 203  *      Add an entry 'new' to the IPC ids idr. The permissions object is
 204  *      initialised and the first free entry is set up and the id assigned
 205  *      is returned. The 'new' entry is returned in a locked state on success.
 206  *      On failure the entry is not locked and a negative err-code is returned.
 207  *
 208  *      Called with ipc_ids.rw_mutex held as a writer.
 209  */
 210
 211 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 212 {
 213         int id, err;
 214
 215         if (size > IPCMNI)
 216                 size = IPCMNI;
 217
 218         if (ids->in_use >= size)
 219                 return -ENOSPC;
 220
 221         err = idr_get_new(&ids->ipcs_idr, new, &id);
 222         if (err)
 223                 return err;
 224
 225         ids->in_use++;
 226
 227         new->cuid = new->uid = current->euid;
 228         new->gid = new->cgid = current->egid;
 229
 230         new->seq = ids->seq++;
 231         if(ids->seq > ids->seq_max)
 232                 ids->seq = 0;
 233
 234         spin_lock_init(&new->lock);
 235         new->deleted = 0;
 236         rcu_read_lock();
 237         spin_lock(&new->lock);
 238         return id;
 239 }
 240
 241 /**
 242  *      ipcget_new      -       create a new ipc object
 243  *      @ns: namespace
 244  *      @ids: IPC identifer set
 245  *      @ops: the actual creation routine to call
 246  *      @params: its parameters
 247  *
 248  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 249  *      when the key is IPC_PRIVATE.
 250  */
 251 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 252                 struct ipc_ops *ops, struct ipc_params *params)
 253 {
 254         int err;
 255 retry:
 256         err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
 257
 258         if (!err)
 259                 return -ENOMEM;
 260
 261         down_write(&ids->rw_mutex);
 262         err = ops->getnew(ns, params);
 263         up_write(&ids->rw_mutex);
 264
 265         if (err == -EAGAIN)
 266                 goto retry;
 267
 268         return err;
 269 }
 270
 271 /**
 272  *      ipc_check_perms -       check security and permissions for an IPC
 273  *      @ipcp: ipc permission set
 274  *      @ops: the actual security routine to call
 275  *      @params: its parameters
 276  *
 277  *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 278  *      when the key is not IPC_PRIVATE and that key already exists in the
 279  *      ids IDR.
 280  *
 281  *      On success, the IPC id is returned.
 282  *
 283  *      It is called with ipc_ids.rw_mutex and ipcp->lock held.
 284  */
 285 static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
 286                         struct ipc_params *params)
 287 {
 288         int err;
 289
 290         if (ipcperms(ipcp, params->flg))
 291                 err = -EACCES;
 292         else {
 293                 err = ops->associate(ipcp, params->flg);
 294                 if (!err)
 295                         err = ipcp->id;
 296         }
 297
 298         return err;
 299 }
 300
 301 /**
 302  *      ipcget_public   -       get an ipc object or create a new one
 303  *      @ns: namespace
 304  *      @ids: IPC identifer set
 305  *      @ops: the actual creation routine to call
 306  *      @params: its parameters
 307  *
 308  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 309  *      when the key is not IPC_PRIVATE.
 310  *      It adds a new entry if the key is not found and does some permission
 311  *      / security checkings if the key is found.
 312  *
 313  *      On success, the ipc id is returned.
 314  */
 315 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 316                 struct ipc_ops *ops, struct ipc_params *params)
 317 {
 318         struct kern_ipc_perm *ipcp;
 319         int flg = params->flg;
 320         int err;
 321 retry:
 322         err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
 323
 324         /*
 325          * Take the lock as a writer since we are potentially going to add
 326          * a new entry + read locks are not "upgradable"
 327          */
 328         down_write(&ids->rw_mutex);
 329         ipcp = ipc_findkey(ids, params->key);
 330         if (ipcp == NULL) {
 331                 /* key not used */
 332                 if (!(flg & IPC_CREAT))
 333                         err = -ENOENT;
 334                 else if (!err)
 335                         err = -ENOMEM;
 336                 else
 337                         err = ops->getnew(ns, params);
 338         } else {
 339                 /* ipc object has been locked by ipc_findkey() */
 340
 341                 if (flg & IPC_CREAT && flg & IPC_EXCL)
 342                         err = -EEXIST;
 343                 else {
 344                         err = 0;
 345                         if (ops->more_checks)
 346                                 err = ops->more_checks(ipcp, params);
 347                         if (!err)
 348                                 /*
 349                                  * ipc_check_perms returns the IPC id on
 350                                  * success
 351                                  */
 352                                 err = ipc_check_perms(ipcp, ops, params);
 353                 }
 354                 ipc_unlock(ipcp);
 355         }
 356         up_write(&ids->rw_mutex);
 357
 358         if (err == -EAGAIN)
 359                 goto retry;
 360
 361         return err;
 362 }
 363
 364
 365 /**
 366  *      ipc_rmid        -       remove an IPC identifier
 367  *      @ids: IPC identifier set
 368  *      @ipcp: ipc perm structure containing the identifier to remove
 369  *
 370  *      ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
 371  *      before this function is called, and remain locked on the exit.
 372  */
 373
 374 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 375 {
 376         int lid = ipcid_to_idx(ipcp->id);
 377
 378         idr_remove(&ids->ipcs_idr, lid);
 379
 380         ids->in_use--;
 381
 382         ipcp->deleted = 1;
 383
 384         return;
 385 }
 386
 387 /**
 388  *      ipc_alloc       -       allocate ipc space
 389  *      @size: size desired
 390  *
 391  *      Allocate memory from the appropriate pools and return a pointer to it.
 392  *      NULL is returned if the allocation fails
 393  */
 394
 395 void* ipc_alloc(int size)
 396 {
 397         void* out;
 398         if(size > PAGE_SIZE)
 399                 out = vmalloc(size);
 400         else
 401                 out = kmalloc(size, GFP_KERNEL);
 402         return out;
 403 }
 404
 405 /**
 406  *      ipc_free        -       free ipc space
 407  *      @ptr: pointer returned by ipc_alloc
 408  *      @size: size of block
 409  *
 410  *      Free a block created with ipc_alloc(). The caller must know the size
 411  *      used in the allocation call.
 412  */
 413
 414 void ipc_free(void* ptr, int size)
 415 {
 416         if(size > PAGE_SIZE)
 417                 vfree(ptr);
 418         else
 419                 kfree(ptr);
 420 }
 421
 422 /*
 423  * rcu allocations:
 424  * There are three headers that are prepended to the actual allocation:
 425  * - during use: ipc_rcu_hdr.
 426  * - during the rcu grace period: ipc_rcu_grace.
 427  * - [only if vmalloc]: ipc_rcu_sched.
 428  * Their lifetime doesn't overlap, thus the headers share the same memory.
 429  * Unlike a normal union, they are right-aligned, thus some container_of
 430  * forward/backward casting is necessary:
 431  */
 432 struct ipc_rcu_hdr
 433 {
 434         int refcount;
 435         int is_vmalloc;
 436         void *data[0];
 437 };
 438
 439
 440 struct ipc_rcu_grace
 441 {
 442         struct rcu_head rcu;
 443         /* "void *" makes sure alignment of following data is sane. */
 444         void *data[0];
 445 };
 446
 447 struct ipc_rcu_sched
 448 {
 449         struct work_struct work;
 450         /* "void *" makes sure alignment of following data is sane. */
 451         void *data[0];
 452 };
 453
 454 #define HDRLEN_KMALLOC          (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
 455                                         sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
 456 #define HDRLEN_VMALLOC          (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
 457                                         sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
 458
 459 static inline int rcu_use_vmalloc(int size)
 460 {
 461         /* Too big for a single page? */
 462         if (HDRLEN_KMALLOC + size > PAGE_SIZE)
 463                 return 1;
 464         return 0;
 465 }
 466
 467 /**
 468  *      ipc_rcu_alloc   -       allocate ipc and rcu space
 469  *      @size: size desired
 470  *
 471  *      Allocate memory for the rcu header structure +  the object.
 472  *      Returns the pointer to the object.
 473  *      NULL is returned if the allocation fails.
 474  */
 475
 476 void* ipc_rcu_alloc(int size)
 477 {
 478         void* out;
 479         /*
 480          * We prepend the allocation with the rcu struct, and
 481          * workqueue if necessary (for vmalloc).
 482          */
 483         if (rcu_use_vmalloc(size)) {
 484                 out = vmalloc(HDRLEN_VMALLOC + size);
 485                 if (out) {
 486                         out += HDRLEN_VMALLOC;
 487                         container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
 488                         container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
 489                 }
 490         } else {
 491                 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
 492                 if (out) {
 493                         out += HDRLEN_KMALLOC;
 494                         container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
 495                         container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
 496                 }
 497         }
 498
 499         return out;
 500 }
 501
 502 void ipc_rcu_getref(void *ptr)
 503 {
 504         container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
 505 }
 506
 507 static void ipc_do_vfree(struct work_struct *work)
 508 {
 509         vfree(container_of(work, struct ipc_rcu_sched, work));
 510 }
 511
 512 /**
 513  * ipc_schedule_free - free ipc + rcu space
 514  * @head: RCU callback structure for queued work
 515  *
 516  * Since RCU callback function is called in bh,
 517  * we need to defer the vfree to schedule_work().
 518  */
 519 static void ipc_schedule_free(struct rcu_head *head)
 520 {
 521         struct ipc_rcu_grace *grace;
 522         struct ipc_rcu_sched *sched;
 523
 524         grace = container_of(head, struct ipc_rcu_grace, rcu);
 525         sched = container_of(&(grace->data[0]), struct ipc_rcu_sched,
 526                                 data[0]);
 527
 528         INIT_WORK(&sched->work, ipc_do_vfree);
 529         schedule_work(&sched->work);
 530 }
 531
 532 /**
 533  * ipc_immediate_free - free ipc + rcu space
 534  * @head: RCU callback structure that contains pointer to be freed
 535  *
 536  * Free from the RCU callback context.
 537  */
 538 static void ipc_immediate_free(struct rcu_head *head)
 539 {
 540         struct ipc_rcu_grace *free =
 541                 container_of(head, struct ipc_rcu_grace, rcu);
 542         kfree(free);
 543 }
 544
 545 void ipc_rcu_putref(void *ptr)
 546 {
 547         if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
 548                 return;
 549
 550         if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
 551                 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
 552                                 ipc_schedule_free);
 553         } else {
 554                 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
 555                                 ipc_immediate_free);
 556         }
 557 }
 558
 559 /**
 560  *      ipcperms        -       check IPC permissions
 561  *      @ipcp: IPC permission set
 562  *      @flag: desired permission set.
 563  *
 564  *      Check user, group, other permissions for access
 565  *      to ipc resources. return 0 if allowed
 566  */
 567
 568 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
 569 {       /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
 570         int requested_mode, granted_mode, err;
 571
 572         if (unlikely((err = audit_ipc_obj(ipcp))))
 573                 return err;
 574         requested_mode = (flag >> 6) | (flag >> 3) | flag;
 575         granted_mode = ipcp->mode;
 576         if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
 577                 granted_mode >>= 6;
 578         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 579                 granted_mode >>= 3;
 580         /* is there some bit set in requested_mode but not in granted_mode? */
 581         if ((requested_mode & ~granted_mode & 0007) &&
 582             !capable(CAP_IPC_OWNER))
 583                 return -1;
 584
 585         return security_ipc_permission(ipcp, flag);
 586 }
 587
 588 /*
 589  * Functions to convert between the kern_ipc_perm structure and the
 590  * old/new ipc_perm structures
 591  */
 592
 593 /**
 594  *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
 595  *      @in: kernel permissions
 596  *      @out: new style IPC permissions
 597  *
 598  *      Turn the kernel object @in into a set of permissions descriptions
 599  *      for returning to userspace (@out).
 600  */
 601
 602
 603 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
 604 {
 605         out->key        = in->key;
 606         out->uid        = in->uid;
 607         out->gid        = in->gid;
 608         out->cuid       = in->cuid;
 609         out->cgid       = in->cgid;
 610         out->mode       = in->mode;
 611         out->seq        = in->seq;
 612 }
 613
 614 /**
 615  *      ipc64_perm_to_ipc_perm  -       convert new ipc permissions to old
 616  *      @in: new style IPC permissions
 617  *      @out: old style IPC permissions
 618  *
 619  *      Turn the new style permissions object @in into a compatibility
 620  *      object and store it into the @out pointer.
 621  */
 622
 623 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
 624 {
 625         out->key        = in->key;
 626         SET_UID(out->uid, in->uid);
 627         SET_GID(out->gid, in->gid);
 628         SET_UID(out->cuid, in->cuid);
 629         SET_GID(out->cgid, in->cgid);
 630         out->mode       = in->mode;
 631         out->seq        = in->seq;
 632 }
 633
 634 /**
 635  * ipc_lock - Lock an ipc structure without rw_mutex held
 636  * @ids: IPC identifier set
 637  * @id: ipc id to look for
 638  *
 639  * Look for an id in the ipc ids idr and lock the associated ipc object.
 640  *
 641  * The ipc object is locked on exit.
 642  *
 643  * This is the routine that should be called when the rw_mutex is not already
 644  * held, i.e. idr tree not protected: it protects the idr tree in read mode
 645  * during the idr_find().
 646  */
 647
 648 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 649 {
 650         struct kern_ipc_perm *out;
 651         int lid = ipcid_to_idx(id);
 652
 653         down_read(&ids->rw_mutex);
 654
 655         rcu_read_lock();
 656         out = idr_find(&ids->ipcs_idr, lid);
 657         if (out == NULL) {
 658                 rcu_read_unlock();
 659                 up_read(&ids->rw_mutex);
 660                 return ERR_PTR(-EINVAL);
 661         }
 662
 663         up_read(&ids->rw_mutex);
 664
 665         spin_lock(&out->lock);
 666
 667         /* ipc_rmid() may have already freed the ID while ipc_lock
 668          * was spinning: here verify that the structure is still valid
 669          */
 670         if (out->deleted) {
 671                 spin_unlock(&out->lock);
 672                 rcu_read_unlock();
 673                 return ERR_PTR(-EINVAL);
 674         }
 675
 676         return out;
 677 }
 678
 679 /**
 680  * ipc_lock_down - Lock an ipc structure with rw_sem held
 681  * @ids: IPC identifier set
 682  * @id: ipc id to look for
 683  *
 684  * Look for an id in the ipc ids idr and lock the associated ipc object.
 685  *
 686  * The ipc object is locked on exit.
 687  *
 688  * This is the routine that should be called when the rw_mutex is already
 689  * held, i.e. idr tree protected.
 690  */
 691
 692 struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
 693 {
 694         struct kern_ipc_perm *out;
 695         int lid = ipcid_to_idx(id);
 696
 697         rcu_read_lock();
 698         out = idr_find(&ids->ipcs_idr, lid);
 699         if (out == NULL) {
 700                 rcu_read_unlock();
 701                 return ERR_PTR(-EINVAL);
 702         }
 703
 704         spin_lock(&out->lock);
 705
 706         /*
 707          * No need to verify that the structure is still valid since the
 708          * rw_mutex is held.
 709          */
 710         return out;
 711 }
 712
 713 struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids, int id)
 714 {
 715         struct kern_ipc_perm *out;
 716
 717         out = ipc_lock_down(ids, id);
 718         if (IS_ERR(out))
 719                 return out;
 720
 721         if (ipc_checkid(out, id)) {
 722                 ipc_unlock(out);
 723                 return ERR_PTR(-EIDRM);
 724         }
 725
 726         return out;
 727 }
 728
 729 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
 730 {
 731         struct kern_ipc_perm *out;
 732
 733         out = ipc_lock(ids, id);
 734         if (IS_ERR(out))
 735                 return out;
 736
 737         if (ipc_checkid(out, id)) {
 738                 ipc_unlock(out);
 739                 return ERR_PTR(-EIDRM);
 740         }
 741
 742         return out;
 743 }
 744
 745 /**
 746  * ipcget - Common sys_*get() code
 747  * @ns : namsepace
 748  * @ids : IPC identifier set
 749  * @ops : operations to be called on ipc object creation, permission checks
 750  *        and further checks
 751  * @params : the parameters needed by the previous operations.
 752  *
 753  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 754  */
 755 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 756                         struct ipc_ops *ops, struct ipc_params *params)
 757 {
 758         if (params->key == IPC_PRIVATE)
 759                 return ipcget_new(ns, ids, ops, params);
 760         else
 761                 return ipcget_public(ns, ids, ops, params);
 762 }
 763
 764 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
 765
 766
 767 /**
 768  *      ipc_parse_version       -       IPC call version
 769  *      @cmd: pointer to command
 770  *
 771  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 772  *      The @cmd value is turned from an encoding command and version into
 773  *      just the command code.
 774  */
 775
 776 int ipc_parse_version (int *cmd)
 777 {
 778         if (*cmd & IPC_64) {
 779                 *cmd ^= IPC_64;
 780                 return IPC_64;
 781         } else {
 782                 return IPC_OLD;
 783         }
 784 }
 785
 786 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
 787
 788 #ifdef CONFIG_PROC_FS
 789 struct ipc_proc_iter {
 790         struct ipc_namespace *ns;
 791         struct ipc_proc_iface *iface;
 792 };
 793
 794 /*
 795  * This routine locks the ipc structure found at least at position pos.
 796  */
 797 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 798                                               loff_t *new_pos)
 799 {
 800         struct kern_ipc_perm *ipc;
 801         int total, id;
 802
 803         total = 0;
 804         for (id = 0; id < pos && total < ids->in_use; id++) {
 805                 ipc = idr_find(&ids->ipcs_idr, id);
 806                 if (ipc != NULL)
 807                         total++;
 808         }
 809
 810         if (total >= ids->in_use)
 811                 return NULL;
 812
 813         for ( ; pos < IPCMNI; pos++) {
 814                 ipc = idr_find(&ids->ipcs_idr, pos);
 815                 if (ipc != NULL) {
 816                         *new_pos = pos + 1;
 817                         ipc_lock_by_ptr(ipc);
 818                         return ipc;
 819                 }
 820         }
 821
 822         /* Out of range - return NULL to terminate iteration */
 823         return NULL;
 824 }
 825
 826 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 827 {
 828         struct ipc_proc_iter *iter = s->private;
 829         struct ipc_proc_iface *iface = iter->iface;
 830         struct kern_ipc_perm *ipc = it;
 831
 832         /* If we had an ipc id locked before, unlock it */
 833         if (ipc && ipc != SEQ_START_TOKEN)
 834                 ipc_unlock(ipc);
 835
 836         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 837 }
 838
 839 /*
 840  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 841  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 842  */
 843 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 844 {
 845         struct ipc_proc_iter *iter = s->private;
 846         struct ipc_proc_iface *iface = iter->iface;
 847         struct ipc_ids *ids;
 848
 849         ids = &iter->ns->ids[iface->ids];
 850
 851         /*
 852          * Take the lock - this will be released by the corresponding
 853          * call to stop().
 854          */
 855         down_read(&ids->rw_mutex);
 856
 857         /* pos < 0 is invalid */
 858         if (*pos < 0)
 859                 return NULL;
 860
 861         /* pos == 0 means header */
 862         if (*pos == 0)
 863                 return SEQ_START_TOKEN;
 864
 865         /* Find the (pos-1)th ipc */
 866         return sysvipc_find_ipc(ids, *pos - 1, pos);
 867 }
 868
 869 static void sysvipc_proc_stop(struct seq_file *s, void *it)
 870 {
 871         struct kern_ipc_perm *ipc = it;
 872         struct ipc_proc_iter *iter = s->private;
 873         struct ipc_proc_iface *iface = iter->iface;
 874         struct ipc_ids *ids;
 875
 876         /* If we had a locked structure, release it */
 877         if (ipc && ipc != SEQ_START_TOKEN)
 878                 ipc_unlock(ipc);
 879
 880         ids = &iter->ns->ids[iface->ids];
 881         /* Release the lock we took in start() */
 882         up_read(&ids->rw_mutex);
 883 }
 884
 885 static int sysvipc_proc_show(struct seq_file *s, void *it)
 886 {
 887         struct ipc_proc_iter *iter = s->private;
 888         struct ipc_proc_iface *iface = iter->iface;
 889
 890         if (it == SEQ_START_TOKEN)
 891                 return seq_puts(s, iface->header);
 892
 893         return iface->show(s, it);
 894 }
 895
 896 static struct seq_operations sysvipc_proc_seqops = {
 897         .start = sysvipc_proc_start,
 898         .stop  = sysvipc_proc_stop,
 899         .next  = sysvipc_proc_next,
 900         .show  = sysvipc_proc_show,
 901 };
 902
 903 static int sysvipc_proc_open(struct inode *inode, struct file *file)
 904 {
 905         int ret;
 906         struct seq_file *seq;
 907         struct ipc_proc_iter *iter;
 908
 909         ret = -ENOMEM;
 910         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 911         if (!iter)
 912                 goto out;
 913
 914         ret = seq_open(file, &sysvipc_proc_seqops);
 915         if (ret)
 916                 goto out_kfree;
 917
 918         seq = file->private_data;
 919         seq->private = iter;
 920
 921         iter->iface = PDE(inode)->data;
 922         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 923 out:
 924         return ret;
 925 out_kfree:
 926         kfree(iter);
 927         goto out;
 928 }
 929
 930 static int sysvipc_proc_release(struct inode *inode, struct file *file)
 931 {
 932         struct seq_file *seq = file->private_data;
 933         struct ipc_proc_iter *iter = seq->private;
 934         put_ipc_ns(iter->ns);
 935         return seq_release_private(inode, file);
 936 }
 937
 938 static const struct file_operations sysvipc_proc_fops = {
 939         .open    = sysvipc_proc_open,
 940         .read    = seq_read,
 941         .llseek  = seq_lseek,
 942         .release = sysvipc_proc_release,
 943 };
 944 #endif /* CONFIG_PROC_FS */