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/notifier.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 #include <linux/rwsem.h>
  37 #include <linux/memory.h>
  38 #include <linux/ipc_namespace.h>
  39
  40 #include <asm/unistd.h>
  41
  42 #include "util.h"
  43
  44 struct ipc_proc_iface {
  45         const char *path;
  46         const char *header;
  47         int ids;
  48         int (*show)(struct seq_file *, void *);
  49 };
  50
  51 static void ipc_memory_notifier(struct work_struct *work)
  52 {
  53         ipcns_notify(IPCNS_MEMCHANGED);
  54 }
  55
  56 static int ipc_memory_callback(struct notifier_block *self,
  57                                 unsigned long action, void *arg)
  58 {
  59         static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier);
  60
  61         switch (action) {
  62         case MEM_ONLINE:    /* memory successfully brought online */
  63         case MEM_OFFLINE:   /* or offline: it's time to recompute msgmni */
  64                 /*
  65                  * This is done by invoking the ipcns notifier chain with the
  66                  * IPC_MEMCHANGED event.
  67                  * In order not to keep the lock on the hotplug memory chain
  68                  * for too long, queue a work item that will, when waken up,
  69                  * activate the ipcns notification chain.
  70                  * No need to keep several ipc work items on the queue.
  71                  */
  72                 if (!work_pending(&ipc_memory_wq))
  73                         schedule_work(&ipc_memory_wq);
  74                 break;
  75         case MEM_GOING_ONLINE:
  76         case MEM_GOING_OFFLINE:
  77         case MEM_CANCEL_ONLINE:
  78         case MEM_CANCEL_OFFLINE:
  79         default:
  80                 break;
  81         }
  82
  83         return NOTIFY_OK;
  84 }
  85
  86 static struct notifier_block ipc_memory_nb = {
  87         .notifier_call = ipc_memory_callback,
  88         .priority = IPC_CALLBACK_PRI,
  89 };
  90
  91 /**
  92  *      ipc_init        -       initialise IPC subsystem
  93  *
  94  *      The various system5 IPC resources (semaphores, messages and shared
  95  *      memory) are initialised
  96  *      A callback routine is registered into the memory hotplug notifier
  97  *      chain: since msgmni scales to lowmem this callback routine will be
  98  *      called upon successful memory add / remove to recompute msmgni.
  99  */
 100
 101 static int __init ipc_init(void)
 102 {
 103         sem_init();
 104         msg_init();
 105         shm_init();
 106         register_hotmemory_notifier(&ipc_memory_nb);
 107         register_ipcns_notifier(&init_ipc_ns);
 108         return 0;
 109 }
 110 __initcall(ipc_init);
 111
 112 /**
 113  *      ipc_init_ids            -       initialise IPC identifiers
 114  *      @ids: Identifier set
 115  *
 116  *      Set up the sequence range to use for the ipc identifier range (limited
 117  *      below IPCMNI) then initialise the ids idr.
 118  */
 119
 120 void ipc_init_ids(struct ipc_ids *ids)
 121 {
 122         init_rwsem(&ids->rw_mutex);
 123
 124         ids->in_use = 0;
 125         ids->seq = 0;
 126         ids->next_id = -1;
 127         {
 128                 int seq_limit = INT_MAX/SEQ_MULTIPLIER;
 129                 if (seq_limit > USHRT_MAX)
 130                         ids->seq_max = USHRT_MAX;
 131                  else
 132                         ids->seq_max = seq_limit;
 133         }
 134
 135         idr_init(&ids->ipcs_idr);
 136 }
 137
 138 #ifdef CONFIG_PROC_FS
 139 static const struct file_operations sysvipc_proc_fops;
 140 /**
 141  *      ipc_init_proc_interface -  Create a proc interface for sysipc types using a seq_file interface.
 142  *      @path: Path in procfs
 143  *      @header: Banner to be printed at the beginning of the file.
 144  *      @ids: ipc id table to iterate.
 145  *      @show: show routine.
 146  */
 147 void __init ipc_init_proc_interface(const char *path, const char *header,
 148                 int ids, int (*show)(struct seq_file *, void *))
 149 {
 150         struct proc_dir_entry *pde;
 151         struct ipc_proc_iface *iface;
 152
 153         iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 154         if (!iface)
 155                 return;
 156         iface->path     = path;
 157         iface->header   = header;
 158         iface->ids      = ids;
 159         iface->show     = show;
 160
 161         pde = proc_create_data(path,
 162                                S_IRUGO,        /* world readable */
 163                                NULL,           /* parent dir */
 164                                &sysvipc_proc_fops,
 165                                iface);
 166         if (!pde) {
 167                 kfree(iface);
 168         }
 169 }
 170 #endif
 171
 172 /**
 173  *      ipc_findkey     -       find a key in an ipc identifier set
 174  *      @ids: Identifier set
 175  *      @key: The key to find
 176  *
 177  *      Requires ipc_ids.rw_mutex locked.
 178  *      Returns the LOCKED pointer to the ipc structure if found or NULL
 179  *      if not.
 180  *      If key is found ipc points to the owning ipc structure
 181  */
 182
 183 static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
 184 {
 185         struct kern_ipc_perm *ipc;
 186         int next_id;
 187         int total;
 188
 189         for (total = 0, next_id = 0; total < ids->in_use; next_id++) {
 190                 ipc = idr_find(&ids->ipcs_idr, next_id);
 191
 192                 if (ipc == NULL)
 193                         continue;
 194
 195                 if (ipc->key != key) {
 196                         total++;
 197                         continue;
 198                 }
 199
 200                 ipc_lock_by_ptr(ipc);
 201                 return ipc;
 202         }
 203
 204         return NULL;
 205 }
 206
 207 /**
 208  *      ipc_get_maxid   -       get the last assigned id
 209  *      @ids: IPC identifier set
 210  *
 211  *      Called with ipc_ids.rw_mutex held.
 212  */
 213
 214 int ipc_get_maxid(struct ipc_ids *ids)
 215 {
 216         struct kern_ipc_perm *ipc;
 217         int max_id = -1;
 218         int total, id;
 219
 220         if (ids->in_use == 0)
 221                 return -1;
 222
 223         if (ids->in_use == IPCMNI)
 224                 return IPCMNI - 1;
 225
 226         /* Look for the last assigned id */
 227         total = 0;
 228         for (id = 0; id < IPCMNI && total < ids->in_use; id++) {
 229                 ipc = idr_find(&ids->ipcs_idr, id);
 230                 if (ipc != NULL) {
 231                         max_id = id;
 232                         total++;
 233                 }
 234         }
 235         return max_id;
 236 }
 237
 238 /**
 239  *      ipc_addid       -       add an IPC identifier
 240  *      @ids: IPC identifier set
 241  *      @new: new IPC permission set
 242  *      @size: limit for the number of used ids
 243  *
 244  *      Add an entry 'new' to the IPC ids idr. The permissions object is
 245  *      initialised and the first free entry is set up and the id assigned
 246  *      is returned. The 'new' entry is returned in a locked state on success.
 247  *      On failure the entry is not locked and a negative err-code is returned.
 248  *
 249  *      Called with ipc_ids.rw_mutex held as a writer.
 250  */
 251
 252 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 253 {
 254         kuid_t euid;
 255         kgid_t egid;
 256         int id;
 257         int next_id = ids->next_id;
 258
 259         if (size > IPCMNI)
 260                 size = IPCMNI;
 261
 262         if (ids->in_use >= size)
 263                 return -ENOSPC;
 264
 265         idr_preload(GFP_KERNEL);
 266
 267         spin_lock_init(&new->lock);
 268         new->deleted = 0;
 269         rcu_read_lock();
 270         spin_lock(&new->lock);
 271
 272         id = idr_alloc(&ids->ipcs_idr, new,
 273                        (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
 274                        GFP_NOWAIT);
 275         idr_preload_end();
 276         if (id < 0) {
 277                 spin_unlock(&new->lock);
 278                 rcu_read_unlock();
 279                 return id;
 280         }
 281
 282         ids->in_use++;
 283
 284         current_euid_egid(&euid, &egid);
 285         new->cuid = new->uid = euid;
 286         new->gid = new->cgid = egid;
 287
 288         if (next_id < 0) {
 289                 new->seq = ids->seq++;
 290                 if (ids->seq > ids->seq_max)
 291                         ids->seq = 0;
 292         } else {
 293                 new->seq = ipcid_to_seqx(next_id);
 294                 ids->next_id = -1;
 295         }
 296
 297         new->id = ipc_buildid(id, new->seq);
 298         return id;
 299 }
 300
 301 /**
 302  *      ipcget_new      -       create a new ipc object
 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 IPC_PRIVATE.
 310  */
 311 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 312                 struct ipc_ops *ops, struct ipc_params *params)
 313 {
 314         int err;
 315
 316         down_write(&ids->rw_mutex);
 317         err = ops->getnew(ns, params);
 318         up_write(&ids->rw_mutex);
 319         return err;
 320 }
 321
 322 /**
 323  *      ipc_check_perms -       check security and permissions for an IPC
 324  *      @ns: IPC namespace
 325  *      @ipcp: ipc permission set
 326  *      @ops: the actual security routine to call
 327  *      @params: its parameters
 328  *
 329  *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 330  *      when the key is not IPC_PRIVATE and that key already exists in the
 331  *      ids IDR.
 332  *
 333  *      On success, the IPC id is returned.
 334  *
 335  *      It is called with ipc_ids.rw_mutex and ipcp->lock held.
 336  */
 337 static int ipc_check_perms(struct ipc_namespace *ns,
 338                            struct kern_ipc_perm *ipcp,
 339                            struct ipc_ops *ops,
 340                            struct ipc_params *params)
 341 {
 342         int err;
 343
 344         if (ipcperms(ns, ipcp, params->flg))
 345                 err = -EACCES;
 346         else {
 347                 err = ops->associate(ipcp, params->flg);
 348                 if (!err)
 349                         err = ipcp->id;
 350         }
 351
 352         return err;
 353 }
 354
 355 /**
 356  *      ipcget_public   -       get an ipc object or create a new one
 357  *      @ns: namespace
 358  *      @ids: IPC identifer set
 359  *      @ops: the actual creation routine to call
 360  *      @params: its parameters
 361  *
 362  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 363  *      when the key is not IPC_PRIVATE.
 364  *      It adds a new entry if the key is not found and does some permission
 365  *      / security checkings if the key is found.
 366  *
 367  *      On success, the ipc id is returned.
 368  */
 369 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 370                 struct ipc_ops *ops, struct ipc_params *params)
 371 {
 372         struct kern_ipc_perm *ipcp;
 373         int flg = params->flg;
 374         int err;
 375
 376         /*
 377          * Take the lock as a writer since we are potentially going to add
 378          * a new entry + read locks are not "upgradable"
 379          */
 380         down_write(&ids->rw_mutex);
 381         ipcp = ipc_findkey(ids, params->key);
 382         if (ipcp == NULL) {
 383                 /* key not used */
 384                 if (!(flg & IPC_CREAT))
 385                         err = -ENOENT;
 386                 else
 387                         err = ops->getnew(ns, params);
 388         } else {
 389                 /* ipc object has been locked by ipc_findkey() */
 390
 391                 if (flg & IPC_CREAT && flg & IPC_EXCL)
 392                         err = -EEXIST;
 393                 else {
 394                         err = 0;
 395                         if (ops->more_checks)
 396                                 err = ops->more_checks(ipcp, params);
 397                         if (!err)
 398                                 /*
 399                                  * ipc_check_perms returns the IPC id on
 400                                  * success
 401                                  */
 402                                 err = ipc_check_perms(ns, ipcp, ops, params);
 403                 }
 404                 ipc_unlock(ipcp);
 405         }
 406         up_write(&ids->rw_mutex);
 407
 408         return err;
 409 }
 410
 411
 412 /**
 413  *      ipc_rmid        -       remove an IPC identifier
 414  *      @ids: IPC identifier set
 415  *      @ipcp: ipc perm structure containing the identifier to remove
 416  *
 417  *      ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
 418  *      before this function is called, and remain locked on the exit.
 419  */
 420
 421 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 422 {
 423         int lid = ipcid_to_idx(ipcp->id);
 424
 425         idr_remove(&ids->ipcs_idr, lid);
 426
 427         ids->in_use--;
 428
 429         ipcp->deleted = 1;
 430
 431         return;
 432 }
 433
 434 /**
 435  *      ipc_alloc       -       allocate ipc space
 436  *      @size: size desired
 437  *
 438  *      Allocate memory from the appropriate pools and return a pointer to it.
 439  *      NULL is returned if the allocation fails
 440  */
 441
 442 void *ipc_alloc(int size)
 443 {
 444         void *out;
 445         if(size > PAGE_SIZE)
 446                 out = vmalloc(size);
 447         else
 448                 out = kmalloc(size, GFP_KERNEL);
 449         return out;
 450 }
 451
 452 /**
 453  *      ipc_free        -       free ipc space
 454  *      @ptr: pointer returned by ipc_alloc
 455  *      @size: size of block
 456  *
 457  *      Free a block created with ipc_alloc(). The caller must know the size
 458  *      used in the allocation call.
 459  */
 460
 461 void ipc_free(void* ptr, int size)
 462 {
 463         if(size > PAGE_SIZE)
 464                 vfree(ptr);
 465         else
 466                 kfree(ptr);
 467 }
 468
 469 struct ipc_rcu {
 470         struct rcu_head rcu;
 471         atomic_t refcount;
 472         /* "void *" makes sure alignment of following data is sane. */
 473         void *data[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 or NULL upon failure.
 482  */
 483 void *ipc_rcu_alloc(int size)
 484 {
 485         /*
 486          * We prepend the allocation with the rcu struct
 487          */
 488         struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
 489         if (unlikely(!out))
 490                 return NULL;
 491         atomic_set(&out->refcount, 1);
 492         return out->data;
 493 }
 494
 495 int ipc_rcu_getref(void *ptr)
 496 {
 497         return atomic_inc_not_zero(&container_of(ptr, struct ipc_rcu, data)->refcount);
 498 }
 499
 500 /**
 501  * ipc_schedule_free - free ipc + rcu space
 502  * @head: RCU callback structure for queued work
 503  */
 504 static void ipc_schedule_free(struct rcu_head *head)
 505 {
 506         vfree(container_of(head, struct ipc_rcu, rcu));
 507 }
 508
 509 void ipc_rcu_putref(void *ptr)
 510 {
 511         struct ipc_rcu *p = container_of(ptr, struct ipc_rcu, data);
 512
 513         if (!atomic_dec_and_test(&p->refcount))
 514                 return;
 515
 516         if (is_vmalloc_addr(ptr)) {
 517                 call_rcu(&p->rcu, ipc_schedule_free);
 518         } else {
 519                 kfree_rcu(p, rcu);
 520         }
 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 rw_mutex 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 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
 682 {
 683         struct kern_ipc_perm *out;
 684
 685         out = ipc_lock(ids, id);
 686         if (IS_ERR(out))
 687                 return out;
 688
 689         if (ipc_checkid(out, id)) {
 690                 ipc_unlock(out);
 691                 return ERR_PTR(-EIDRM);
 692         }
 693
 694         return out;
 695 }
 696
 697 /**
 698  * ipcget - Common sys_*get() code
 699  * @ns : namsepace
 700  * @ids : IPC identifier set
 701  * @ops : operations to be called on ipc object creation, permission checks
 702  *        and further checks
 703  * @params : the parameters needed by the previous operations.
 704  *
 705  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 706  */
 707 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 708                         struct ipc_ops *ops, struct ipc_params *params)
 709 {
 710         if (params->key == IPC_PRIVATE)
 711                 return ipcget_new(ns, ids, ops, params);
 712         else
 713                 return ipcget_public(ns, ids, ops, params);
 714 }
 715
 716 /**
 717  * ipc_update_perm - update the permissions of an IPC.
 718  * @in:  the permission given as input.
 719  * @out: the permission of the ipc to set.
 720  */
 721 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 722 {
 723         kuid_t uid = make_kuid(current_user_ns(), in->uid);
 724         kgid_t gid = make_kgid(current_user_ns(), in->gid);
 725         if (!uid_valid(uid) || !gid_valid(gid))
 726                 return -EINVAL;
 727
 728         out->uid = uid;
 729         out->gid = gid;
 730         out->mode = (out->mode & ~S_IRWXUGO)
 731                 | (in->mode & S_IRWXUGO);
 732
 733         return 0;
 734 }
 735
 736 /**
 737  * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd
 738  * @ns:  the ipc namespace
 739  * @ids:  the table of ids where to look for the ipc
 740  * @id:   the id of the ipc to retrieve
 741  * @cmd:  the cmd to check
 742  * @perm: the permission to set
 743  * @extra_perm: one extra permission parameter used by msq
 744  *
 745  * This function does some common audit and permissions check for some IPC_XXX
 746  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
 747  * It must be called without any lock held and
 748  *  - retrieves the ipc with the given id in the given table.
 749  *  - performs some audit and permission check, depending on the given cmd
 750  *  - returns the ipc with both ipc and rw_mutex locks held in case of success
 751  *    or an err-code without any lock held otherwise.
 752  */
 753 struct kern_ipc_perm *ipcctl_pre_down(struct ipc_namespace *ns,
 754                                       struct ipc_ids *ids, int id, int cmd,
 755                                       struct ipc64_perm *perm, int extra_perm)
 756 {
 757         struct kern_ipc_perm *ipcp;
 758
 759         ipcp = ipcctl_pre_down_nolock(ns, ids, id, cmd, perm, extra_perm);
 760         if (IS_ERR(ipcp))
 761                 goto out;
 762
 763         spin_lock(&ipcp->lock);
 764 out:
 765         return ipcp;
 766 }
 767
 768 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 769                                              struct ipc_ids *ids, int id, int cmd,
 770                                              struct ipc64_perm *perm, int extra_perm)
 771 {
 772         kuid_t euid;
 773         int err = -EPERM;
 774         struct kern_ipc_perm *ipcp;
 775
 776         down_write(&ids->rw_mutex);
 777         rcu_read_lock();
 778
 779         ipcp = ipc_obtain_object_check(ids, id);
 780         if (IS_ERR(ipcp)) {
 781                 err = PTR_ERR(ipcp);
 782                 goto out_up;
 783         }
 784
 785         audit_ipc_obj(ipcp);
 786         if (cmd == IPC_SET)
 787                 audit_ipc_set_perm(extra_perm, perm->uid,
 788                                    perm->gid, perm->mode);
 789
 790         euid = current_euid();
 791         if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
 792             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 793                 return ipcp;
 794
 795 out_up:
 796         /*
 797          * Unsuccessful lookup, unlock and return
 798          * the corresponding error.
 799          */
 800         rcu_read_unlock();
 801         up_write(&ids->rw_mutex);
 802
 803         return ERR_PTR(err);
 804 }
 805
 806 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 807
 808
 809 /**
 810  *      ipc_parse_version       -       IPC call version
 811  *      @cmd: pointer to command
 812  *
 813  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 814  *      The @cmd value is turned from an encoding command and version into
 815  *      just the command code.
 816  */
 817
 818 int ipc_parse_version (int *cmd)
 819 {
 820         if (*cmd & IPC_64) {
 821                 *cmd ^= IPC_64;
 822                 return IPC_64;
 823         } else {
 824                 return IPC_OLD;
 825         }
 826 }
 827
 828 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
 829
 830 #ifdef CONFIG_PROC_FS
 831 struct ipc_proc_iter {
 832         struct ipc_namespace *ns;
 833         struct ipc_proc_iface *iface;
 834 };
 835
 836 /*
 837  * This routine locks the ipc structure found at least at position pos.
 838  */
 839 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 840                                               loff_t *new_pos)
 841 {
 842         struct kern_ipc_perm *ipc;
 843         int total, id;
 844
 845         total = 0;
 846         for (id = 0; id < pos && total < ids->in_use; id++) {
 847                 ipc = idr_find(&ids->ipcs_idr, id);
 848                 if (ipc != NULL)
 849                         total++;
 850         }
 851
 852         if (total >= ids->in_use)
 853                 return NULL;
 854
 855         for ( ; pos < IPCMNI; pos++) {
 856                 ipc = idr_find(&ids->ipcs_idr, pos);
 857                 if (ipc != NULL) {
 858                         *new_pos = pos + 1;
 859                         ipc_lock_by_ptr(ipc);
 860                         return ipc;
 861                 }
 862         }
 863
 864         /* Out of range - return NULL to terminate iteration */
 865         return NULL;
 866 }
 867
 868 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 869 {
 870         struct ipc_proc_iter *iter = s->private;
 871         struct ipc_proc_iface *iface = iter->iface;
 872         struct kern_ipc_perm *ipc = it;
 873
 874         /* If we had an ipc id locked before, unlock it */
 875         if (ipc && ipc != SEQ_START_TOKEN)
 876                 ipc_unlock(ipc);
 877
 878         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 879 }
 880
 881 /*
 882  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 883  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 884  */
 885 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 886 {
 887         struct ipc_proc_iter *iter = s->private;
 888         struct ipc_proc_iface *iface = iter->iface;
 889         struct ipc_ids *ids;
 890
 891         ids = &iter->ns->ids[iface->ids];
 892
 893         /*
 894          * Take the lock - this will be released by the corresponding
 895          * call to stop().
 896          */
 897         down_read(&ids->rw_mutex);
 898
 899         /* pos < 0 is invalid */
 900         if (*pos < 0)
 901                 return NULL;
 902
 903         /* pos == 0 means header */
 904         if (*pos == 0)
 905                 return SEQ_START_TOKEN;
 906
 907         /* Find the (pos-1)th ipc */
 908         return sysvipc_find_ipc(ids, *pos - 1, pos);
 909 }
 910
 911 static void sysvipc_proc_stop(struct seq_file *s, void *it)
 912 {
 913         struct kern_ipc_perm *ipc = it;
 914         struct ipc_proc_iter *iter = s->private;
 915         struct ipc_proc_iface *iface = iter->iface;
 916         struct ipc_ids *ids;
 917
 918         /* If we had a locked structure, release it */
 919         if (ipc && ipc != SEQ_START_TOKEN)
 920                 ipc_unlock(ipc);
 921
 922         ids = &iter->ns->ids[iface->ids];
 923         /* Release the lock we took in start() */
 924         up_read(&ids->rw_mutex);
 925 }
 926
 927 static int sysvipc_proc_show(struct seq_file *s, void *it)
 928 {
 929         struct ipc_proc_iter *iter = s->private;
 930         struct ipc_proc_iface *iface = iter->iface;
 931
 932         if (it == SEQ_START_TOKEN)
 933                 return seq_puts(s, iface->header);
 934
 935         return iface->show(s, it);
 936 }
 937
 938 static const struct seq_operations sysvipc_proc_seqops = {
 939         .start = sysvipc_proc_start,
 940         .stop  = sysvipc_proc_stop,
 941         .next  = sysvipc_proc_next,
 942         .show  = sysvipc_proc_show,
 943 };
 944
 945 static int sysvipc_proc_open(struct inode *inode, struct file *file)
 946 {
 947         int ret;
 948         struct seq_file *seq;
 949         struct ipc_proc_iter *iter;
 950
 951         ret = -ENOMEM;
 952         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 953         if (!iter)
 954                 goto out;
 955
 956         ret = seq_open(file, &sysvipc_proc_seqops);
 957         if (ret)
 958                 goto out_kfree;
 959
 960         seq = file->private_data;
 961         seq->private = iter;
 962
 963         iter->iface = PDE_DATA(inode);
 964         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 965 out:
 966         return ret;
 967 out_kfree:
 968         kfree(iter);
 969         goto out;
 970 }
 971
 972 static int sysvipc_proc_release(struct inode *inode, struct file *file)
 973 {
 974         struct seq_file *seq = file->private_data;
 975         struct ipc_proc_iter *iter = seq->private;
 976         put_ipc_ns(iter->ns);
 977         return seq_release_private(inode, file);
 978 }
 979
 980 static const struct file_operations sysvipc_proc_fops = {
 981         .open    = sysvipc_proc_open,
 982         .read    = seq_read,
 983         .llseek  = seq_lseek,
 984         .release = sysvipc_proc_release,
 985 };
 986 #endif /* CONFIG_PROC_FS */