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                 rcu_read_lock();
 209                 ipc_lock_object(ipc);
 210                 return ipc;
 211         }
 212
 213         return NULL;
 214 }
 215
 216 /**
 217  *      ipc_get_maxid   -       get the last assigned id
 218  *      @ids: IPC identifier set
 219  *
 220  *      Called with ipc_ids.rwsem held.
 221  */
 222
 223 int ipc_get_maxid(struct ipc_ids *ids)
 224 {
 225         struct kern_ipc_perm *ipc;
 226         int max_id = -1;
 227         int total, id;
 228
 229         if (ids->in_use == 0)
 230                 return -1;
 231
 232         if (ids->in_use == IPCMNI)
 233                 return IPCMNI - 1;
 234
 235         /* Look for the last assigned id */
 236         total = 0;
 237         for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
 238                 ipc = idr_find(&ids->ipcs_idr, id);
 239                 if (ipc != NULL) {
 240                         max_id = id;
 241                         total++;
 242                 }
 243         }
 244         return max_id;
 245 }
 246
 247 /**
 248  *      ipc_addid       -       add an IPC identifier
 249  *      @ids: IPC identifier set
 250  *      @new: new IPC permission set
 251  *      @size: limit for the number of used ids
 252  *
 253  *      Add an entry 'new' to the IPC ids idr. The permissions object is
 254  *      initialised and the first free entry is set up and the id assigned
 255  *      is returned. The 'new' entry is returned in a locked state on success.
 256  *      On failure the entry is not locked and a negative err-code is returned.
 257  *
 258  *      Called with writer ipc_ids.rwsem held.
 259  */
 260 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 261 {
 262         kuid_t euid;
 263         kgid_t egid;
 264         int id;
 265         int next_id = ids->next_id;
 266
 267         if (size > IPCMNI)
 268                 size = IPCMNI;
 269
 270         if (ids->in_use >= size)
 271                 return -ENOSPC;
 272
 273         idr_preload(GFP_KERNEL);
 274
 275         spin_lock_init(&new->lock);
 276         new->deleted = 0;
 277         rcu_read_lock();
 278         spin_lock(&new->lock);
 279
 280         id = idr_alloc(&ids->ipcs_idr, new,
 281                        (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
 282                        GFP_NOWAIT);
 283         idr_preload_end();
 284         if (id < 0) {
 285                 spin_unlock(&new->lock);
 286                 rcu_read_unlock();
 287                 return id;
 288         }
 289
 290         ids->in_use++;
 291
 292         current_euid_egid(&euid, &egid);
 293         new->cuid = new->uid = euid;
 294         new->gid = new->cgid = egid;
 295
 296         if (next_id < 0) {
 297                 new->seq = ids->seq++;
 298                 if (ids->seq > ids->seq_max)
 299                         ids->seq = 0;
 300         } else {
 301                 new->seq = ipcid_to_seqx(next_id);
 302                 ids->next_id = -1;
 303         }
 304
 305         new->id = ipc_buildid(id, new->seq);
 306         return id;
 307 }
 308
 309 /**
 310  *      ipcget_new      -       create a new ipc object
 311  *      @ns: namespace
 312  *      @ids: IPC identifer set
 313  *      @ops: the actual creation routine to call
 314  *      @params: its parameters
 315  *
 316  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 317  *      when the key is IPC_PRIVATE.
 318  */
 319 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 320                 struct ipc_ops *ops, struct ipc_params *params)
 321 {
 322         int err;
 323
 324         down_write(&ids->rwsem);
 325         err = ops->getnew(ns, params);
 326         up_write(&ids->rwsem);
 327         return err;
 328 }
 329
 330 /**
 331  *      ipc_check_perms -       check security and permissions for an IPC
 332  *      @ns: IPC namespace
 333  *      @ipcp: ipc permission set
 334  *      @ops: the actual security routine to call
 335  *      @params: its parameters
 336  *
 337  *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 338  *      when the key is not IPC_PRIVATE and that key already exists in the
 339  *      ids IDR.
 340  *
 341  *      On success, the IPC id is returned.
 342  *
 343  *      It is called with ipc_ids.rwsem and ipcp->lock held.
 344  */
 345 static int ipc_check_perms(struct ipc_namespace *ns,
 346                            struct kern_ipc_perm *ipcp,
 347                            struct ipc_ops *ops,
 348                            struct ipc_params *params)
 349 {
 350         int err;
 351
 352         if (ipcperms(ns, ipcp, params->flg))
 353                 err = -EACCES;
 354         else {
 355                 err = ops->associate(ipcp, params->flg);
 356                 if (!err)
 357                         err = ipcp->id;
 358         }
 359
 360         return err;
 361 }
 362
 363 /**
 364  *      ipcget_public   -       get an ipc object or create a new one
 365  *      @ns: namespace
 366  *      @ids: IPC identifer set
 367  *      @ops: the actual creation routine to call
 368  *      @params: its parameters
 369  *
 370  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 371  *      when the key is not IPC_PRIVATE.
 372  *      It adds a new entry if the key is not found and does some permission
 373  *      / security checkings if the key is found.
 374  *
 375  *      On success, the ipc id is returned.
 376  */
 377 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 378                 struct ipc_ops *ops, struct ipc_params *params)
 379 {
 380         struct kern_ipc_perm *ipcp;
 381         int flg = params->flg;
 382         int err;
 383
 384         /*
 385          * Take the lock as a writer since we are potentially going to add
 386          * a new entry + read locks are not "upgradable"
 387          */
 388         down_write(&ids->rwsem);
 389         ipcp = ipc_findkey(ids, params->key);
 390         if (ipcp == NULL) {
 391                 /* key not used */
 392                 if (!(flg & IPC_CREAT))
 393                         err = -ENOENT;
 394                 else
 395                         err = ops->getnew(ns, params);
 396         } else {
 397                 /* ipc object has been locked by ipc_findkey() */
 398
 399                 if (flg & IPC_CREAT && flg & IPC_EXCL)
 400                         err = -EEXIST;
 401                 else {
 402                         err = 0;
 403                         if (ops->more_checks)
 404                                 err = ops->more_checks(ipcp, params);
 405                         if (!err)
 406                                 /*
 407                                  * ipc_check_perms returns the IPC id on
 408                                  * success
 409                                  */
 410                                 err = ipc_check_perms(ns, ipcp, ops, params);
 411                 }
 412                 ipc_unlock(ipcp);
 413         }
 414         up_write(&ids->rwsem);
 415
 416         return err;
 417 }
 418
 419
 420 /**
 421  *      ipc_rmid        -       remove an IPC identifier
 422  *      @ids: IPC identifier set
 423  *      @ipcp: ipc perm structure containing the identifier to remove
 424  *
 425  *      ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
 426  *      before this function is called, and remain locked on the exit.
 427  */
 428
 429 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 430 {
 431         int lid = ipcid_to_idx(ipcp->id);
 432
 433         idr_remove(&ids->ipcs_idr, lid);
 434
 435         ids->in_use--;
 436
 437         ipcp->deleted = 1;
 438
 439         return;
 440 }
 441
 442 /**
 443  *      ipc_alloc       -       allocate ipc space
 444  *      @size: size desired
 445  *
 446  *      Allocate memory from the appropriate pools and return a pointer to it.
 447  *      NULL is returned if the allocation fails
 448  */
 449
 450 void *ipc_alloc(int size)
 451 {
 452         void *out;
 453         if(size > PAGE_SIZE)
 454                 out = vmalloc(size);
 455         else
 456                 out = kmalloc(size, GFP_KERNEL);
 457         return out;
 458 }
 459
 460 /**
 461  *      ipc_free        -       free ipc space
 462  *      @ptr: pointer returned by ipc_alloc
 463  *      @size: size of block
 464  *
 465  *      Free a block created with ipc_alloc(). The caller must know the size
 466  *      used in the allocation call.
 467  */
 468
 469 void ipc_free(void* ptr, int size)
 470 {
 471         if(size > PAGE_SIZE)
 472                 vfree(ptr);
 473         else
 474                 kfree(ptr);
 475 }
 476
 477 /**
 478  *      ipc_rcu_alloc   -       allocate ipc and rcu space
 479  *      @size: size desired
 480  *
 481  *      Allocate memory for the rcu header structure +  the object.
 482  *      Returns the pointer to the object or NULL upon failure.
 483  */
 484 void *ipc_rcu_alloc(int size)
 485 {
 486         /*
 487          * We prepend the allocation with the rcu struct
 488          */
 489         struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
 490         if (unlikely(!out))
 491                 return NULL;
 492         atomic_set(&out->refcount, 1);
 493         return out + 1;
 494 }
 495
 496 int ipc_rcu_getref(void *ptr)
 497 {
 498         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 499
 500         return atomic_inc_not_zero(&p->refcount);
 501 }
 502
 503 void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head))
 504 {
 505         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 506
 507         if (!atomic_dec_and_test(&p->refcount))
 508                 return;
 509
 510         call_rcu(&p->rcu, func);
 511 }
 512
 513 void ipc_rcu_free(struct rcu_head *head)
 514 {
 515         struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
 516
 517         if (is_vmalloc_addr(p))
 518                 vfree(p);
 519         else
 520                 kfree(p);
 521 }
 522
 523 /**
 524  *      ipcperms        -       check IPC permissions
 525  *      @ns: IPC namespace
 526  *      @ipcp: IPC permission set
 527  *      @flag: desired permission set.
 528  *
 529  *      Check user, group, other permissions for access
 530  *      to ipc resources. return 0 if allowed
 531  *
 532  *      @flag will most probably be 0 or S_...UGO from <linux/stat.h>
 533  */
 534
 535 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 536 {
 537         kuid_t euid = current_euid();
 538         int requested_mode, granted_mode;
 539
 540         audit_ipc_obj(ipcp);
 541         requested_mode = (flag >> 6) | (flag >> 3) | flag;
 542         granted_mode = ipcp->mode;
 543         if (uid_eq(euid, ipcp->cuid) ||
 544             uid_eq(euid, ipcp->uid))
 545                 granted_mode >>= 6;
 546         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 547                 granted_mode >>= 3;
 548         /* is there some bit set in requested_mode but not in granted_mode? */
 549         if ((requested_mode & ~granted_mode & 0007) &&
 550             !ns_capable(ns->user_ns, CAP_IPC_OWNER))
 551                 return -1;
 552
 553         return security_ipc_permission(ipcp, flag);
 554 }
 555
 556 /*
 557  * Functions to convert between the kern_ipc_perm structure and the
 558  * old/new ipc_perm structures
 559  */
 560
 561 /**
 562  *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
 563  *      @in: kernel permissions
 564  *      @out: new style IPC permissions
 565  *
 566  *      Turn the kernel object @in into a set of permissions descriptions
 567  *      for returning to userspace (@out).
 568  */
 569
 570
 571 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
 572 {
 573         out->key        = in->key;
 574         out->uid        = from_kuid_munged(current_user_ns(), in->uid);
 575         out->gid        = from_kgid_munged(current_user_ns(), in->gid);
 576         out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
 577         out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
 578         out->mode       = in->mode;
 579         out->seq        = in->seq;
 580 }
 581
 582 /**
 583  *      ipc64_perm_to_ipc_perm  -       convert new ipc permissions to old
 584  *      @in: new style IPC permissions
 585  *      @out: old style IPC permissions
 586  *
 587  *      Turn the new style permissions object @in into a compatibility
 588  *      object and store it into the @out pointer.
 589  */
 590
 591 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
 592 {
 593         out->key        = in->key;
 594         SET_UID(out->uid, in->uid);
 595         SET_GID(out->gid, in->gid);
 596         SET_UID(out->cuid, in->cuid);
 597         SET_GID(out->cgid, in->cgid);
 598         out->mode       = in->mode;
 599         out->seq        = in->seq;
 600 }
 601
 602 /**
 603  * ipc_obtain_object
 604  * @ids: ipc identifier set
 605  * @id: ipc id to look for
 606  *
 607  * Look for an id in the ipc ids idr and return associated ipc object.
 608  *
 609  * Call inside the RCU critical section.
 610  * The ipc object is *not* locked on exit.
 611  */
 612 struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
 613 {
 614         struct kern_ipc_perm *out;
 615         int lid = ipcid_to_idx(id);
 616
 617         out = idr_find(&ids->ipcs_idr, lid);
 618         if (!out)
 619                 return ERR_PTR(-EINVAL);
 620
 621         return out;
 622 }
 623
 624 /**
 625  * ipc_lock - Lock an ipc structure without rwsem held
 626  * @ids: IPC identifier set
 627  * @id: ipc id to look for
 628  *
 629  * Look for an id in the ipc ids idr and lock the associated ipc object.
 630  *
 631  * The ipc object is locked on successful exit.
 632  */
 633 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 634 {
 635         struct kern_ipc_perm *out;
 636
 637         rcu_read_lock();
 638         out = ipc_obtain_object(ids, id);
 639         if (IS_ERR(out))
 640                 goto err1;
 641
 642         spin_lock(&out->lock);
 643
 644         /* ipc_rmid() may have already freed the ID while ipc_lock
 645          * was spinning: here verify that the structure is still valid
 646          */
 647         if (!out->deleted)
 648                 return out;
 649
 650         spin_unlock(&out->lock);
 651         out = ERR_PTR(-EINVAL);
 652 err1:
 653         rcu_read_unlock();
 654         return out;
 655 }
 656
 657 /**
 658  * ipc_obtain_object_check
 659  * @ids: ipc identifier set
 660  * @id: ipc id to look for
 661  *
 662  * Similar to ipc_obtain_object() but also checks
 663  * the ipc object reference counter.
 664  *
 665  * Call inside the RCU critical section.
 666  * The ipc object is *not* locked on exit.
 667  */
 668 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
 669 {
 670         struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
 671
 672         if (IS_ERR(out))
 673                 goto out;
 674
 675         if (ipc_checkid(out, id))
 676                 return ERR_PTR(-EIDRM);
 677 out:
 678         return out;
 679 }
 680
 681 /**
 682  * ipcget - Common sys_*get() code
 683  * @ns : namsepace
 684  * @ids : IPC identifier set
 685  * @ops : operations to be called on ipc object creation, permission checks
 686  *        and further checks
 687  * @params : the parameters needed by the previous operations.
 688  *
 689  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 690  */
 691 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 692                         struct ipc_ops *ops, struct ipc_params *params)
 693 {
 694         if (params->key == IPC_PRIVATE)
 695                 return ipcget_new(ns, ids, ops, params);
 696         else
 697                 return ipcget_public(ns, ids, ops, params);
 698 }
 699
 700 /**
 701  * ipc_update_perm - update the permissions of an IPC.
 702  * @in:  the permission given as input.
 703  * @out: the permission of the ipc to set.
 704  */
 705 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 706 {
 707         kuid_t uid = make_kuid(current_user_ns(), in->uid);
 708         kgid_t gid = make_kgid(current_user_ns(), in->gid);
 709         if (!uid_valid(uid) || !gid_valid(gid))
 710                 return -EINVAL;
 711
 712         out->uid = uid;
 713         out->gid = gid;
 714         out->mode = (out->mode & ~S_IRWXUGO)
 715                 | (in->mode & S_IRWXUGO);
 716
 717         return 0;
 718 }
 719
 720 /**
 721  * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
 722  * @ns:  the ipc namespace
 723  * @ids:  the table of ids where to look for the ipc
 724  * @id:   the id of the ipc to retrieve
 725  * @cmd:  the cmd to check
 726  * @perm: the permission to set
 727  * @extra_perm: one extra permission parameter used by msq
 728  *
 729  * This function does some common audit and permissions check for some IPC_XXX
 730  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
 731  * It must be called without any lock held and
 732  *  - retrieves the ipc with the given id in the given table.
 733  *  - performs some audit and permission check, depending on the given cmd
 734  *  - returns a pointer to the ipc object or otherwise, the corresponding error.
 735  *
 736  * Call holding the both the rwsem and the rcu read lock.
 737  */
 738 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 739                                         struct ipc_ids *ids, int id, int cmd,
 740                                         struct ipc64_perm *perm, int extra_perm)
 741 {
 742         kuid_t euid;
 743         int err = -EPERM;
 744         struct kern_ipc_perm *ipcp;
 745
 746         ipcp = ipc_obtain_object_check(ids, id);
 747         if (IS_ERR(ipcp)) {
 748                 err = PTR_ERR(ipcp);
 749                 goto err;
 750         }
 751
 752         audit_ipc_obj(ipcp);
 753         if (cmd == IPC_SET)
 754                 audit_ipc_set_perm(extra_perm, perm->uid,
 755                                    perm->gid, perm->mode);
 756
 757         euid = current_euid();
 758         if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
 759             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 760                 return ipcp; /* successful lookup */
 761 err:
 762         return ERR_PTR(err);
 763 }
 764
 765 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 766
 767
 768 /**
 769  *      ipc_parse_version       -       IPC call version
 770  *      @cmd: pointer to command
 771  *
 772  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 773  *      The @cmd value is turned from an encoding command and version into
 774  *      just the command code.
 775  */
 776
 777 int ipc_parse_version (int *cmd)
 778 {
 779         if (*cmd & IPC_64) {
 780                 *cmd ^= IPC_64;
 781                 return IPC_64;
 782         } else {
 783                 return IPC_OLD;
 784         }
 785 }
 786
 787 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
 788
 789 #ifdef CONFIG_PROC_FS
 790 struct ipc_proc_iter {
 791         struct ipc_namespace *ns;
 792         struct ipc_proc_iface *iface;
 793 };
 794
 795 /*
 796  * This routine locks the ipc structure found at least at position pos.
 797  */
 798 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 799                                               loff_t *new_pos)
 800 {
 801         struct kern_ipc_perm *ipc;
 802         int total, id;
 803
 804         total = 0;
 805         for (id = 0; id < pos && total < ids->in_use; id++) {
 806                 ipc = idr_find(&ids->ipcs_idr, id);
 807                 if (ipc != NULL)
 808                         total++;
 809         }
 810
 811         if (total >= ids->in_use)
 812                 return NULL;
 813
 814         for ( ; pos < IPCMNI; pos++) {
 815                 ipc = idr_find(&ids->ipcs_idr, pos);
 816                 if (ipc != NULL) {
 817                         *new_pos = pos + 1;
 818                         rcu_read_lock();
 819                         ipc_lock_object(ipc);
 820                         return ipc;
 821                 }
 822         }
 823
 824         /* Out of range - return NULL to terminate iteration */
 825         return NULL;
 826 }
 827
 828 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 829 {
 830         struct ipc_proc_iter *iter = s->private;
 831         struct ipc_proc_iface *iface = iter->iface;
 832         struct kern_ipc_perm *ipc = it;
 833
 834         /* If we had an ipc id locked before, unlock it */
 835         if (ipc && ipc != SEQ_START_TOKEN)
 836                 ipc_unlock(ipc);
 837
 838         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 839 }
 840
 841 /*
 842  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 843  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 844  */
 845 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 846 {
 847         struct ipc_proc_iter *iter = s->private;
 848         struct ipc_proc_iface *iface = iter->iface;
 849         struct ipc_ids *ids;
 850
 851         ids = &iter->ns->ids[iface->ids];
 852
 853         /*
 854          * Take the lock - this will be released by the corresponding
 855          * call to stop().
 856          */
 857         down_read(&ids->rwsem);
 858
 859         /* pos < 0 is invalid */
 860         if (*pos < 0)
 861                 return NULL;
 862
 863         /* pos == 0 means header */
 864         if (*pos == 0)
 865                 return SEQ_START_TOKEN;
 866
 867         /* Find the (pos-1)th ipc */
 868         return sysvipc_find_ipc(ids, *pos - 1, pos);
 869 }
 870
 871 static void sysvipc_proc_stop(struct seq_file *s, void *it)
 872 {
 873         struct kern_ipc_perm *ipc = it;
 874         struct ipc_proc_iter *iter = s->private;
 875         struct ipc_proc_iface *iface = iter->iface;
 876         struct ipc_ids *ids;
 877
 878         /* If we had a locked structure, release it */
 879         if (ipc && ipc != SEQ_START_TOKEN)
 880                 ipc_unlock(ipc);
 881
 882         ids = &iter->ns->ids[iface->ids];
 883         /* Release the lock we took in start() */
 884         up_read(&ids->rwsem);
 885 }
 886
 887 static int sysvipc_proc_show(struct seq_file *s, void *it)
 888 {
 889         struct ipc_proc_iter *iter = s->private;
 890         struct ipc_proc_iface *iface = iter->iface;
 891
 892         if (it == SEQ_START_TOKEN)
 893                 return seq_puts(s, iface->header);
 894
 895         return iface->show(s, it);
 896 }
 897
 898 static const struct seq_operations sysvipc_proc_seqops = {
 899         .start = sysvipc_proc_start,
 900         .stop  = sysvipc_proc_stop,
 901         .next  = sysvipc_proc_next,
 902         .show  = sysvipc_proc_show,
 903 };
 904
 905 static int sysvipc_proc_open(struct inode *inode, struct file *file)
 906 {
 907         int ret;
 908         struct seq_file *seq;
 909         struct ipc_proc_iter *iter;
 910
 911         ret = -ENOMEM;
 912         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 913         if (!iter)
 914                 goto out;
 915
 916         ret = seq_open(file, &sysvipc_proc_seqops);
 917         if (ret)
 918                 goto out_kfree;
 919
 920         seq = file->private_data;
 921         seq->private = iter;
 922
 923         iter->iface = PDE_DATA(inode);
 924         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 925 out:
 926         return ret;
 927 out_kfree:
 928         kfree(iter);
 929         goto out;
 930 }
 931
 932 static int sysvipc_proc_release(struct inode *inode, struct file *file)
 933 {
 934         struct seq_file *seq = file->private_data;
 935         struct ipc_proc_iter *iter = seq->private;
 936         put_ipc_ns(iter->ns);
 937         return seq_release_private(inode, file);
 938 }
 939
 940 static const struct file_operations sysvipc_proc_fops = {
 941         .open    = sysvipc_proc_open,
 942         .read    = seq_read,
 943         .llseek  = seq_lseek,
 944         .release = sysvipc_proc_release,
 945 };
 946 #endif /* CONFIG_PROC_FS */