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/smp_lock.h>
  25 #include <linux/vmalloc.h>
  26 #include <linux/slab.h>
  27 #include <linux/capability.h>
  28 #include <linux/highuid.h>
  29 #include <linux/security.h>
  30 #include <linux/rcupdate.h>
  31 #include <linux/workqueue.h>
  32 #include <linux/seq_file.h>
  33 #include <linux/proc_fs.h>
  34 #include <linux/audit.h>
  35 #include <linux/nsproxy.h>
  36
  37 #include <asm/unistd.h>
  38
  39 #include "util.h"
  40
  41 struct ipc_proc_iface {
  42         const char *path;
  43         const char *header;
  44         int ids;
  45         int (*show)(struct seq_file *, void *);
  46 };
  47
  48 struct ipc_namespace init_ipc_ns = {
  49         .kref = {
  50                 .refcount       = ATOMIC_INIT(2),
  51         },
  52 };
  53
  54 #ifdef CONFIG_IPC_NS
  55 static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns)
  56 {
  57         int err;
  58         struct ipc_namespace *ns;
  59
  60         err = -ENOMEM;
  61         ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL);
  62         if (ns == NULL)
  63                 goto err_mem;
  64
  65         err = sem_init_ns(ns);
  66         if (err)
  67                 goto err_sem;
  68         err = msg_init_ns(ns);
  69         if (err)
  70                 goto err_msg;
  71         err = shm_init_ns(ns);
  72         if (err)
  73                 goto err_shm;
  74
  75         kref_init(&ns->kref);
  76         return ns;
  77
  78 err_shm:
  79         msg_exit_ns(ns);
  80 err_msg:
  81         sem_exit_ns(ns);
  82 err_sem:
  83         kfree(ns);
  84 err_mem:
  85         return ERR_PTR(err);
  86 }
  87
  88 int unshare_ipcs(unsigned long unshare_flags, struct ipc_namespace **new_ipc)
  89 {
  90         struct ipc_namespace *new;
  91
  92         if (unshare_flags & CLONE_NEWIPC) {
  93                 if (!capable(CAP_SYS_ADMIN))
  94                         return -EPERM;
  95
  96                 new = clone_ipc_ns(current->nsproxy->ipc_ns);
  97                 if (IS_ERR(new))
  98                         return PTR_ERR(new);
  99
 100                 *new_ipc = new;
 101         }
 102
 103         return 0;
 104 }
 105
 106 int copy_ipcs(unsigned long flags, struct task_struct *tsk)
 107 {
 108         struct ipc_namespace *old_ns = tsk->nsproxy->ipc_ns;
 109         struct ipc_namespace *new_ns;
 110         int err = 0;
 111
 112         if (!old_ns)
 113                 return 0;
 114
 115         get_ipc_ns(old_ns);
 116
 117         if (!(flags & CLONE_NEWIPC))
 118                 return 0;
 119
 120         if (!capable(CAP_SYS_ADMIN)) {
 121                 err = -EPERM;
 122                 goto out;
 123         }
 124
 125         new_ns = clone_ipc_ns(old_ns);
 126         if (!new_ns) {
 127                 err = -ENOMEM;
 128                 goto out;
 129         }
 130
 131         tsk->nsproxy->ipc_ns = new_ns;
 132 out:
 133         put_ipc_ns(old_ns);
 134         return err;
 135 }
 136
 137 void free_ipc_ns(struct kref *kref)
 138 {
 139         struct ipc_namespace *ns;
 140
 141         ns = container_of(kref, struct ipc_namespace, kref);
 142         sem_exit_ns(ns);
 143         msg_exit_ns(ns);
 144         shm_exit_ns(ns);
 145         kfree(ns);
 146 }
 147 #else
 148 int copy_ipcs(unsigned long flags, struct task_struct *tsk)
 149 {
 150         if (flags & CLONE_NEWIPC)
 151                 return -EINVAL;
 152         return 0;
 153 }
 154 #endif
 155
 156 /**
 157  *      ipc_init        -       initialise IPC subsystem
 158  *
 159  *      The various system5 IPC resources (semaphores, messages and shared
 160  *      memory) are initialised
 161  */
 162
 163 static int __init ipc_init(void)
 164 {
 165         sem_init();
 166         msg_init();
 167         shm_init();
 168         return 0;
 169 }
 170 __initcall(ipc_init);
 171
 172 /**
 173  *      ipc_init_ids            -       initialise IPC identifiers
 174  *      @ids: Identifier set
 175  *      @size: Number of identifiers
 176  *
 177  *      Given a size for the ipc identifier range (limited below IPCMNI)
 178  *      set up the sequence range to use then allocate and initialise the
 179  *      array itself.
 180  */
 181
 182 void __ipc_init ipc_init_ids(struct ipc_ids* ids, int size)
 183 {
 184         int i;
 185
 186         mutex_init(&ids->mutex);
 187
 188         if(size > IPCMNI)
 189                 size = IPCMNI;
 190         ids->in_use = 0;
 191         ids->max_id = -1;
 192         ids->seq = 0;
 193         {
 194                 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
 195                 if(seq_limit > USHRT_MAX)
 196                         ids->seq_max = USHRT_MAX;
 197                  else
 198                         ids->seq_max = seq_limit;
 199         }
 200
 201         ids->entries = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*size +
 202                                      sizeof(struct ipc_id_ary));
 203
 204         if(ids->entries == NULL) {
 205                 printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
 206                 size = 0;
 207                 ids->entries = &ids->nullentry;
 208         }
 209         ids->entries->size = size;
 210         for(i=0;i<size;i++)
 211                 ids->entries->p[i] = NULL;
 212 }
 213
 214 #ifdef CONFIG_PROC_FS
 215 static const struct file_operations sysvipc_proc_fops;
 216 /**
 217  *      ipc_init_proc_interface -  Create a proc interface for sysipc types using a seq_file interface.
 218  *      @path: Path in procfs
 219  *      @header: Banner to be printed at the beginning of the file.
 220  *      @ids: ipc id table to iterate.
 221  *      @show: show routine.
 222  */
 223 void __init ipc_init_proc_interface(const char *path, const char *header,
 224                 int ids, int (*show)(struct seq_file *, void *))
 225 {
 226         struct proc_dir_entry *pde;
 227         struct ipc_proc_iface *iface;
 228
 229         iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 230         if (!iface)
 231                 return;
 232         iface->path     = path;
 233         iface->header   = header;
 234         iface->ids      = ids;
 235         iface->show     = show;
 236
 237         pde = create_proc_entry(path,
 238                                 S_IRUGO,        /* world readable */
 239                                 NULL            /* parent dir */);
 240         if (pde) {
 241                 pde->data = iface;
 242                 pde->proc_fops = &sysvipc_proc_fops;
 243         } else {
 244                 kfree(iface);
 245         }
 246 }
 247 #endif
 248
 249 /**
 250  *      ipc_findkey     -       find a key in an ipc identifier set
 251  *      @ids: Identifier set
 252  *      @key: The key to find
 253  *
 254  *      Requires ipc_ids.mutex locked.
 255  *      Returns the identifier if found or -1 if not.
 256  */
 257
 258 int ipc_findkey(struct ipc_ids* ids, key_t key)
 259 {
 260         int id;
 261         struct kern_ipc_perm* p;
 262         int max_id = ids->max_id;
 263
 264         /*
 265          * rcu_dereference() is not needed here
 266          * since ipc_ids.mutex is held
 267          */
 268         for (id = 0; id <= max_id; id++) {
 269                 p = ids->entries->p[id];
 270                 if(p==NULL)
 271                         continue;
 272                 if (key == p->key)
 273                         return id;
 274         }
 275         return -1;
 276 }
 277
 278 /*
 279  * Requires ipc_ids.mutex locked
 280  */
 281 static int grow_ary(struct ipc_ids* ids, int newsize)
 282 {
 283         struct ipc_id_ary* new;
 284         struct ipc_id_ary* old;
 285         int i;
 286         int size = ids->entries->size;
 287
 288         if(newsize > IPCMNI)
 289                 newsize = IPCMNI;
 290         if(newsize <= size)
 291                 return newsize;
 292
 293         new = ipc_rcu_alloc(sizeof(struct kern_ipc_perm *)*newsize +
 294                             sizeof(struct ipc_id_ary));
 295         if(new == NULL)
 296                 return size;
 297         new->size = newsize;
 298         memcpy(new->p, ids->entries->p, sizeof(struct kern_ipc_perm *)*size);
 299         for(i=size;i<newsize;i++) {
 300                 new->p[i] = NULL;
 301         }
 302         old = ids->entries;
 303
 304         /*
 305          * Use rcu_assign_pointer() to make sure the memcpyed contents
 306          * of the new array are visible before the new array becomes visible.
 307          */
 308         rcu_assign_pointer(ids->entries, new);
 309
 310         __ipc_fini_ids(ids, old);
 311         return newsize;
 312 }
 313
 314 /**
 315  *      ipc_addid       -       add an IPC identifier
 316  *      @ids: IPC identifier set
 317  *      @new: new IPC permission set
 318  *      @size: new size limit for the id array
 319  *
 320  *      Add an entry 'new' to the IPC arrays. The permissions object is
 321  *      initialised and the first free entry is set up and the id assigned
 322  *      is returned. The list is returned in a locked state on success.
 323  *      On failure the list is not locked and -1 is returned.
 324  *
 325  *      Called with ipc_ids.mutex held.
 326  */
 327
 328 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 329 {
 330         int id;
 331
 332         size = grow_ary(ids,size);
 333
 334         /*
 335          * rcu_dereference()() is not needed here since
 336          * ipc_ids.mutex is held
 337          */
 338         for (id = 0; id < size; id++) {
 339                 if(ids->entries->p[id] == NULL)
 340                         goto found;
 341         }
 342         return -1;
 343 found:
 344         ids->in_use++;
 345         if (id > ids->max_id)
 346                 ids->max_id = id;
 347
 348         new->cuid = new->uid = current->euid;
 349         new->gid = new->cgid = current->egid;
 350
 351         new->seq = ids->seq++;
 352         if(ids->seq > ids->seq_max)
 353                 ids->seq = 0;
 354
 355         spin_lock_init(&new->lock);
 356         new->deleted = 0;
 357         rcu_read_lock();
 358         spin_lock(&new->lock);
 359         ids->entries->p[id] = new;
 360         return id;
 361 }
 362
 363 /**
 364  *      ipc_rmid        -       remove an IPC identifier
 365  *      @ids: identifier set
 366  *      @id: Identifier to remove
 367  *
 368  *      The identifier must be valid, and in use. The kernel will panic if
 369  *      fed an invalid identifier. The entry is removed and internal
 370  *      variables recomputed. The object associated with the identifier
 371  *      is returned.
 372  *      ipc_ids.mutex and the spinlock for this ID is hold before this function
 373  *      is called, and remain locked on the exit.
 374  */
 375
 376 struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
 377 {
 378         struct kern_ipc_perm* p;
 379         int lid = id % SEQ_MULTIPLIER;
 380         BUG_ON(lid >= ids->entries->size);
 381
 382         /*
 383          * do not need a rcu_dereference()() here to force ordering
 384          * on Alpha, since the ipc_ids.mutex is held.
 385          */
 386         p = ids->entries->p[lid];
 387         ids->entries->p[lid] = NULL;
 388         BUG_ON(p==NULL);
 389         ids->in_use--;
 390
 391         if (lid == ids->max_id) {
 392                 do {
 393                         lid--;
 394                         if(lid == -1)
 395                                 break;
 396                 } while (ids->entries->p[lid] == NULL);
 397                 ids->max_id = lid;
 398         }
 399         p->deleted = 1;
 400         return p;
 401 }
 402
 403 /**
 404  *      ipc_alloc       -       allocate ipc space
 405  *      @size: size desired
 406  *
 407  *      Allocate memory from the appropriate pools and return a pointer to it.
 408  *      NULL is returned if the allocation fails
 409  */
 410
 411 void* ipc_alloc(int size)
 412 {
 413         void* out;
 414         if(size > PAGE_SIZE)
 415                 out = vmalloc(size);
 416         else
 417                 out = kmalloc(size, GFP_KERNEL);
 418         return out;
 419 }
 420
 421 /**
 422  *      ipc_free        -       free ipc space
 423  *      @ptr: pointer returned by ipc_alloc
 424  *      @size: size of block
 425  *
 426  *      Free a block created with ipc_alloc(). The caller must know the size
 427  *      used in the allocation call.
 428  */
 429
 430 void ipc_free(void* ptr, int size)
 431 {
 432         if(size > PAGE_SIZE)
 433                 vfree(ptr);
 434         else
 435                 kfree(ptr);
 436 }
 437
 438 /*
 439  * rcu allocations:
 440  * There are three headers that are prepended to the actual allocation:
 441  * - during use: ipc_rcu_hdr.
 442  * - during the rcu grace period: ipc_rcu_grace.
 443  * - [only if vmalloc]: ipc_rcu_sched.
 444  * Their lifetime doesn't overlap, thus the headers share the same memory.
 445  * Unlike a normal union, they are right-aligned, thus some container_of
 446  * forward/backward casting is necessary:
 447  */
 448 struct ipc_rcu_hdr
 449 {
 450         int refcount;
 451         int is_vmalloc;
 452         void *data[0];
 453 };
 454
 455
 456 struct ipc_rcu_grace
 457 {
 458         struct rcu_head rcu;
 459         /* "void *" makes sure alignment of following data is sane. */
 460         void *data[0];
 461 };
 462
 463 struct ipc_rcu_sched
 464 {
 465         struct work_struct work;
 466         /* "void *" makes sure alignment of following data is sane. */
 467         void *data[0];
 468 };
 469
 470 #define HDRLEN_KMALLOC          (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \
 471                                         sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr))
 472 #define HDRLEN_VMALLOC          (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \
 473                                         sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC)
 474
 475 static inline int rcu_use_vmalloc(int size)
 476 {
 477         /* Too big for a single page? */
 478         if (HDRLEN_KMALLOC + size > PAGE_SIZE)
 479                 return 1;
 480         return 0;
 481 }
 482
 483 /**
 484  *      ipc_rcu_alloc   -       allocate ipc and rcu space
 485  *      @size: size desired
 486  *
 487  *      Allocate memory for the rcu header structure +  the object.
 488  *      Returns the pointer to the object.
 489  *      NULL is returned if the allocation fails.
 490  */
 491
 492 void* ipc_rcu_alloc(int size)
 493 {
 494         void* out;
 495         /*
 496          * We prepend the allocation with the rcu struct, and
 497          * workqueue if necessary (for vmalloc).
 498          */
 499         if (rcu_use_vmalloc(size)) {
 500                 out = vmalloc(HDRLEN_VMALLOC + size);
 501                 if (out) {
 502                         out += HDRLEN_VMALLOC;
 503                         container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1;
 504                         container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
 505                 }
 506         } else {
 507                 out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL);
 508                 if (out) {
 509                         out += HDRLEN_KMALLOC;
 510                         container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0;
 511                         container_of(out, struct ipc_rcu_hdr, data)->refcount = 1;
 512                 }
 513         }
 514
 515         return out;
 516 }
 517
 518 void ipc_rcu_getref(void *ptr)
 519 {
 520         container_of(ptr, struct ipc_rcu_hdr, data)->refcount++;
 521 }
 522
 523 static void ipc_do_vfree(struct work_struct *work)
 524 {
 525         vfree(container_of(work, struct ipc_rcu_sched, work));
 526 }
 527
 528 /**
 529  * ipc_schedule_free - free ipc + rcu space
 530  * @head: RCU callback structure for queued work
 531  *
 532  * Since RCU callback function is called in bh,
 533  * we need to defer the vfree to schedule_work().
 534  */
 535 static void ipc_schedule_free(struct rcu_head *head)
 536 {
 537         struct ipc_rcu_grace *grace =
 538                 container_of(head, struct ipc_rcu_grace, rcu);
 539         struct ipc_rcu_sched *sched =
 540                         container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]);
 541
 542         INIT_WORK(&sched->work, ipc_do_vfree);
 543         schedule_work(&sched->work);
 544 }
 545
 546 /**
 547  * ipc_immediate_free - free ipc + rcu space
 548  * @head: RCU callback structure that contains pointer to be freed
 549  *
 550  * Free from the RCU callback context.
 551  */
 552 static void ipc_immediate_free(struct rcu_head *head)
 553 {
 554         struct ipc_rcu_grace *free =
 555                 container_of(head, struct ipc_rcu_grace, rcu);
 556         kfree(free);
 557 }
 558
 559 void ipc_rcu_putref(void *ptr)
 560 {
 561         if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0)
 562                 return;
 563
 564         if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) {
 565                 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
 566                                 ipc_schedule_free);
 567         } else {
 568                 call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu,
 569                                 ipc_immediate_free);
 570         }
 571 }
 572
 573 /**
 574  *      ipcperms        -       check IPC permissions
 575  *      @ipcp: IPC permission set
 576  *      @flag: desired permission set.
 577  *
 578  *      Check user, group, other permissions for access
 579  *      to ipc resources. return 0 if allowed
 580  */
 581
 582 int ipcperms (struct kern_ipc_perm *ipcp, short flag)
 583 {       /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
 584         int requested_mode, granted_mode, err;
 585
 586         if (unlikely((err = audit_ipc_obj(ipcp))))
 587                 return err;
 588         requested_mode = (flag >> 6) | (flag >> 3) | flag;
 589         granted_mode = ipcp->mode;
 590         if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
 591                 granted_mode >>= 6;
 592         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 593                 granted_mode >>= 3;
 594         /* is there some bit set in requested_mode but not in granted_mode? */
 595         if ((requested_mode & ~granted_mode & 0007) &&
 596             !capable(CAP_IPC_OWNER))
 597                 return -1;
 598
 599         return security_ipc_permission(ipcp, flag);
 600 }
 601
 602 /*
 603  * Functions to convert between the kern_ipc_perm structure and the
 604  * old/new ipc_perm structures
 605  */
 606
 607 /**
 608  *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
 609  *      @in: kernel permissions
 610  *      @out: new style IPC permissions
 611  *
 612  *      Turn the kernel object @in into a set of permissions descriptions
 613  *      for returning to userspace (@out).
 614  */
 615
 616
 617 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
 618 {
 619         out->key        = in->key;
 620         out->uid        = in->uid;
 621         out->gid        = in->gid;
 622         out->cuid       = in->cuid;
 623         out->cgid       = in->cgid;
 624         out->mode       = in->mode;
 625         out->seq        = in->seq;
 626 }
 627
 628 /**
 629  *      ipc64_perm_to_ipc_perm  -       convert old ipc permissions to new
 630  *      @in: new style IPC permissions
 631  *      @out: old style IPC permissions
 632  *
 633  *      Turn the new style permissions object @in into a compatibility
 634  *      object and store it into the @out pointer.
 635  */
 636
 637 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
 638 {
 639         out->key        = in->key;
 640         SET_UID(out->uid, in->uid);
 641         SET_GID(out->gid, in->gid);
 642         SET_UID(out->cuid, in->cuid);
 643         SET_GID(out->cgid, in->cgid);
 644         out->mode       = in->mode;
 645         out->seq        = in->seq;
 646 }
 647
 648 /*
 649  * So far only shm_get_stat() calls ipc_get() via shm_get(), so ipc_get()
 650  * is called with shm_ids.mutex locked.  Since grow_ary() is also called with
 651  * shm_ids.mutex down(for Shared Memory), there is no need to add read
 652  * barriers here to gurantee the writes in grow_ary() are seen in order
 653  * here (for Alpha).
 654  *
 655  * However ipc_get() itself does not necessary require ipc_ids.mutex down. So
 656  * if in the future ipc_get() is used by other places without ipc_ids.mutex
 657  * down, then ipc_get() needs read memery barriers as ipc_lock() does.
 658  */
 659 struct kern_ipc_perm* ipc_get(struct ipc_ids* ids, int id)
 660 {
 661         struct kern_ipc_perm* out;
 662         int lid = id % SEQ_MULTIPLIER;
 663         if(lid >= ids->entries->size)
 664                 return NULL;
 665         out = ids->entries->p[lid];
 666         return out;
 667 }
 668
 669 struct kern_ipc_perm* ipc_lock(struct ipc_ids* ids, int id)
 670 {
 671         struct kern_ipc_perm* out;
 672         int lid = id % SEQ_MULTIPLIER;
 673         struct ipc_id_ary* entries;
 674
 675         rcu_read_lock();
 676         entries = rcu_dereference(ids->entries);
 677         if(lid >= entries->size) {
 678                 rcu_read_unlock();
 679                 return NULL;
 680         }
 681         out = entries->p[lid];
 682         if(out == NULL) {
 683                 rcu_read_unlock();
 684                 return NULL;
 685         }
 686         spin_lock(&out->lock);
 687
 688         /* ipc_rmid() may have already freed the ID while ipc_lock
 689          * was spinning: here verify that the structure is still valid
 690          */
 691         if (out->deleted) {
 692                 spin_unlock(&out->lock);
 693                 rcu_read_unlock();
 694                 return NULL;
 695         }
 696         return out;
 697 }
 698
 699 void ipc_lock_by_ptr(struct kern_ipc_perm *perm)
 700 {
 701         rcu_read_lock();
 702         spin_lock(&perm->lock);
 703 }
 704
 705 void ipc_unlock(struct kern_ipc_perm* perm)
 706 {
 707         spin_unlock(&perm->lock);
 708         rcu_read_unlock();
 709 }
 710
 711 int ipc_buildid(struct ipc_ids* ids, int id, int seq)
 712 {
 713         return SEQ_MULTIPLIER*seq + id;
 714 }
 715
 716 int ipc_checkid(struct ipc_ids* ids, struct kern_ipc_perm* ipcp, int uid)
 717 {
 718         if(uid/SEQ_MULTIPLIER != ipcp->seq)
 719                 return 1;
 720         return 0;
 721 }
 722
 723 #ifdef __ARCH_WANT_IPC_PARSE_VERSION
 724
 725
 726 /**
 727  *      ipc_parse_version       -       IPC call version
 728  *      @cmd: pointer to command
 729  *
 730  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 731  *      The @cmd value is turned from an encoding command and version into
 732  *      just the command code.
 733  */
 734
 735 int ipc_parse_version (int *cmd)
 736 {
 737         if (*cmd & IPC_64) {
 738                 *cmd ^= IPC_64;
 739                 return IPC_64;
 740         } else {
 741                 return IPC_OLD;
 742         }
 743 }
 744
 745 #endif /* __ARCH_WANT_IPC_PARSE_VERSION */
 746
 747 #ifdef CONFIG_PROC_FS
 748 struct ipc_proc_iter {
 749         struct ipc_namespace *ns;
 750         struct ipc_proc_iface *iface;
 751 };
 752
 753 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 754 {
 755         struct ipc_proc_iter *iter = s->private;
 756         struct ipc_proc_iface *iface = iter->iface;
 757         struct kern_ipc_perm *ipc = it;
 758         loff_t p;
 759         struct ipc_ids *ids;
 760
 761         ids = iter->ns->ids[iface->ids];
 762
 763         /* If we had an ipc id locked before, unlock it */
 764         if (ipc && ipc != SEQ_START_TOKEN)
 765                 ipc_unlock(ipc);
 766
 767         /*
 768          * p = *pos - 1 (because id 0 starts at position 1)
 769          *          + 1 (because we increment the position by one)
 770          */
 771         for (p = *pos; p <= ids->max_id; p++) {
 772                 if ((ipc = ipc_lock(ids, p)) != NULL) {
 773                         *pos = p + 1;
 774                         return ipc;
 775                 }
 776         }
 777
 778         /* Out of range - return NULL to terminate iteration */
 779         return NULL;
 780 }
 781
 782 /*
 783  * File positions: pos 0 -> header, pos n -> ipc id + 1.
 784  * SeqFile iterator: iterator value locked shp or SEQ_TOKEN_START.
 785  */
 786 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 787 {
 788         struct ipc_proc_iter *iter = s->private;
 789         struct ipc_proc_iface *iface = iter->iface;
 790         struct kern_ipc_perm *ipc;
 791         loff_t p;
 792         struct ipc_ids *ids;
 793
 794         ids = iter->ns->ids[iface->ids];
 795
 796         /*
 797          * Take the lock - this will be released by the corresponding
 798          * call to stop().
 799          */
 800         mutex_lock(&ids->mutex);
 801
 802         /* pos < 0 is invalid */
 803         if (*pos < 0)
 804                 return NULL;
 805
 806         /* pos == 0 means header */
 807         if (*pos == 0)
 808                 return SEQ_START_TOKEN;
 809
 810         /* Find the (pos-1)th ipc */
 811         for (p = *pos - 1; p <= ids->max_id; p++) {
 812                 if ((ipc = ipc_lock(ids, p)) != NULL) {
 813                         *pos = p + 1;
 814                         return ipc;
 815                 }
 816         }
 817         return NULL;
 818 }
 819
 820 static void sysvipc_proc_stop(struct seq_file *s, void *it)
 821 {
 822         struct kern_ipc_perm *ipc = it;
 823         struct ipc_proc_iter *iter = s->private;
 824         struct ipc_proc_iface *iface = iter->iface;
 825         struct ipc_ids *ids;
 826
 827         /* If we had a locked segment, release it */
 828         if (ipc && ipc != SEQ_START_TOKEN)
 829                 ipc_unlock(ipc);
 830
 831         ids = iter->ns->ids[iface->ids];
 832         /* Release the lock we took in start() */
 833         mutex_unlock(&ids->mutex);
 834 }
 835
 836 static int sysvipc_proc_show(struct seq_file *s, void *it)
 837 {
 838         struct ipc_proc_iter *iter = s->private;
 839         struct ipc_proc_iface *iface = iter->iface;
 840
 841         if (it == SEQ_START_TOKEN)
 842                 return seq_puts(s, iface->header);
 843
 844         return iface->show(s, it);
 845 }
 846
 847 static struct seq_operations sysvipc_proc_seqops = {
 848         .start = sysvipc_proc_start,
 849         .stop  = sysvipc_proc_stop,
 850         .next  = sysvipc_proc_next,
 851         .show  = sysvipc_proc_show,
 852 };
 853
 854 static int sysvipc_proc_open(struct inode *inode, struct file *file)
 855 {
 856         int ret;
 857         struct seq_file *seq;
 858         struct ipc_proc_iter *iter;
 859
 860         ret = -ENOMEM;
 861         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 862         if (!iter)
 863                 goto out;
 864
 865         ret = seq_open(file, &sysvipc_proc_seqops);
 866         if (ret)
 867                 goto out_kfree;
 868
 869         seq = file->private_data;
 870         seq->private = iter;
 871
 872         iter->iface = PDE(inode)->data;
 873         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 874 out:
 875         return ret;
 876 out_kfree:
 877         kfree(iter);
 878         goto out;
 879 }
 880
 881 static int sysvipc_proc_release(struct inode *inode, struct file *file)
 882 {
 883         struct seq_file *seq = file->private_data;
 884         struct ipc_proc_iter *iter = seq->private;
 885         put_ipc_ns(iter->ns);
 886         return seq_release_private(inode, file);
 887 }
 888
 889 static const struct file_operations sysvipc_proc_fops = {
 890         .open    = sysvipc_proc_open,
 891         .read    = seq_read,
 892         .llseek  = seq_lseek,
 893         .release = sysvipc_proc_release,
 894 };
 895 #endif /* CONFIG_PROC_FS */