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