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 writer ipc_ids.rw_mutex held.
 250  */
 251 int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
 252 {
 253         kuid_t euid;
 254         kgid_t egid;
 255         int id;
 256         int next_id = ids->next_id;
 257
 258         if (size > IPCMNI)
 259                 size = IPCMNI;
 260
 261         if (ids->in_use >= size)
 262                 return -ENOSPC;
 263
 264         idr_preload(GFP_KERNEL);
 265
 266         spin_lock_init(&new->lock);
 267         new->deleted = 0;
 268         rcu_read_lock();
 269         spin_lock(&new->lock);
 270
 271         id = idr_alloc(&ids->ipcs_idr, new,
 272                        (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
 273                        GFP_NOWAIT);
 274         idr_preload_end();
 275         if (id < 0) {
 276                 spin_unlock(&new->lock);
 277                 rcu_read_unlock();
 278                 return id;
 279         }
 280
 281         ids->in_use++;
 282
 283         current_euid_egid(&euid, &egid);
 284         new->cuid = new->uid = euid;
 285         new->gid = new->cgid = egid;
 286
 287         if (next_id < 0) {
 288                 new->seq = ids->seq++;
 289                 if (ids->seq > ids->seq_max)
 290                         ids->seq = 0;
 291         } else {
 292                 new->seq = ipcid_to_seqx(next_id);
 293                 ids->next_id = -1;
 294         }
 295
 296         new->id = ipc_buildid(id, new->seq);
 297         return id;
 298 }
 299
 300 /**
 301  *      ipcget_new      -       create a new ipc object
 302  *      @ns: namespace
 303  *      @ids: IPC identifer set
 304  *      @ops: the actual creation routine to call
 305  *      @params: its parameters
 306  *
 307  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 308  *      when the key is IPC_PRIVATE.
 309  */
 310 static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
 311                 struct ipc_ops *ops, struct ipc_params *params)
 312 {
 313         int err;
 314
 315         down_write(&ids->rw_mutex);
 316         err = ops->getnew(ns, params);
 317         up_write(&ids->rw_mutex);
 318         return err;
 319 }
 320
 321 /**
 322  *      ipc_check_perms -       check security and permissions for an IPC
 323  *      @ns: IPC namespace
 324  *      @ipcp: ipc permission set
 325  *      @ops: the actual security routine to call
 326  *      @params: its parameters
 327  *
 328  *      This routine is called by sys_msgget(), sys_semget() and sys_shmget()
 329  *      when the key is not IPC_PRIVATE and that key already exists in the
 330  *      ids IDR.
 331  *
 332  *      On success, the IPC id is returned.
 333  *
 334  *      It is called with ipc_ids.rw_mutex and ipcp->lock held.
 335  */
 336 static int ipc_check_perms(struct ipc_namespace *ns,
 337                            struct kern_ipc_perm *ipcp,
 338                            struct ipc_ops *ops,
 339                            struct ipc_params *params)
 340 {
 341         int err;
 342
 343         if (ipcperms(ns, ipcp, params->flg))
 344                 err = -EACCES;
 345         else {
 346                 err = ops->associate(ipcp, params->flg);
 347                 if (!err)
 348                         err = ipcp->id;
 349         }
 350
 351         return err;
 352 }
 353
 354 /**
 355  *      ipcget_public   -       get an ipc object or create a new one
 356  *      @ns: namespace
 357  *      @ids: IPC identifer set
 358  *      @ops: the actual creation routine to call
 359  *      @params: its parameters
 360  *
 361  *      This routine is called by sys_msgget, sys_semget() and sys_shmget()
 362  *      when the key is not IPC_PRIVATE.
 363  *      It adds a new entry if the key is not found and does some permission
 364  *      / security checkings if the key is found.
 365  *
 366  *      On success, the ipc id is returned.
 367  */
 368 static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
 369                 struct ipc_ops *ops, struct ipc_params *params)
 370 {
 371         struct kern_ipc_perm *ipcp;
 372         int flg = params->flg;
 373         int err;
 374
 375         /*
 376          * Take the lock as a writer since we are potentially going to add
 377          * a new entry + read locks are not "upgradable"
 378          */
 379         down_write(&ids->rw_mutex);
 380         ipcp = ipc_findkey(ids, params->key);
 381         if (ipcp == NULL) {
 382                 /* key not used */
 383                 if (!(flg & IPC_CREAT))
 384                         err = -ENOENT;
 385                 else
 386                         err = ops->getnew(ns, params);
 387         } else {
 388                 /* ipc object has been locked by ipc_findkey() */
 389
 390                 if (flg & IPC_CREAT && flg & IPC_EXCL)
 391                         err = -EEXIST;
 392                 else {
 393                         err = 0;
 394                         if (ops->more_checks)
 395                                 err = ops->more_checks(ipcp, params);
 396                         if (!err)
 397                                 /*
 398                                  * ipc_check_perms returns the IPC id on
 399                                  * success
 400                                  */
 401                                 err = ipc_check_perms(ns, ipcp, ops, params);
 402                 }
 403                 ipc_unlock(ipcp);
 404         }
 405         up_write(&ids->rw_mutex);
 406
 407         return err;
 408 }
 409
 410
 411 /**
 412  *      ipc_rmid        -       remove an IPC identifier
 413  *      @ids: IPC identifier set
 414  *      @ipcp: ipc perm structure containing the identifier to remove
 415  *
 416  *      ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
 417  *      before this function is called, and remain locked on the exit.
 418  */
 419
 420 void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
 421 {
 422         int lid = ipcid_to_idx(ipcp->id);
 423
 424         idr_remove(&ids->ipcs_idr, lid);
 425
 426         ids->in_use--;
 427
 428         ipcp->deleted = 1;
 429
 430         return;
 431 }
 432
 433 /**
 434  *      ipc_alloc       -       allocate ipc space
 435  *      @size: size desired
 436  *
 437  *      Allocate memory from the appropriate pools and return a pointer to it.
 438  *      NULL is returned if the allocation fails
 439  */
 440
 441 void *ipc_alloc(int size)
 442 {
 443         void *out;
 444         if(size > PAGE_SIZE)
 445                 out = vmalloc(size);
 446         else
 447                 out = kmalloc(size, GFP_KERNEL);
 448         return out;
 449 }
 450
 451 /**
 452  *      ipc_free        -       free ipc space
 453  *      @ptr: pointer returned by ipc_alloc
 454  *      @size: size of block
 455  *
 456  *      Free a block created with ipc_alloc(). The caller must know the size
 457  *      used in the allocation call.
 458  */
 459
 460 void ipc_free(void* ptr, int size)
 461 {
 462         if(size > PAGE_SIZE)
 463                 vfree(ptr);
 464         else
 465                 kfree(ptr);
 466 }
 467
 468 struct ipc_rcu {
 469         struct rcu_head rcu;
 470         atomic_t refcount;
 471 } ____cacheline_aligned_in_smp;
 472
 473 /**
 474  *      ipc_rcu_alloc   -       allocate ipc and rcu space
 475  *      @size: size desired
 476  *
 477  *      Allocate memory for the rcu header structure +  the object.
 478  *      Returns the pointer to the object or NULL upon failure.
 479  */
 480 void *ipc_rcu_alloc(int size)
 481 {
 482         /*
 483          * We prepend the allocation with the rcu struct
 484          */
 485         struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size);
 486         if (unlikely(!out))
 487                 return NULL;
 488         atomic_set(&out->refcount, 1);
 489         return out + 1;
 490 }
 491
 492 int ipc_rcu_getref(void *ptr)
 493 {
 494         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 495
 496         return atomic_inc_not_zero(&p->refcount);
 497 }
 498
 499 /**
 500  * ipc_schedule_free - free ipc + rcu space
 501  * @head: RCU callback structure for queued work
 502  */
 503 static void ipc_schedule_free(struct rcu_head *head)
 504 {
 505         vfree(container_of(head, struct ipc_rcu, rcu));
 506 }
 507
 508 void ipc_rcu_putref(void *ptr)
 509 {
 510         struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1;
 511
 512         if (!atomic_dec_and_test(&p->refcount))
 513                 return;
 514
 515         if (is_vmalloc_addr(ptr)) {
 516                 call_rcu(&p->rcu, ipc_schedule_free);
 517         } else {
 518                 kfree_rcu(p, rcu);
 519         }
 520 }
 521
 522 /**
 523  *      ipcperms        -       check IPC permissions
 524  *      @ns: IPC namespace
 525  *      @ipcp: IPC permission set
 526  *      @flag: desired permission set.
 527  *
 528  *      Check user, group, other permissions for access
 529  *      to ipc resources. return 0 if allowed
 530  *
 531  *      @flag will most probably be 0 or S_...UGO from <linux/stat.h>
 532  */
 533
 534 int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
 535 {
 536         kuid_t euid = current_euid();
 537         int requested_mode, granted_mode;
 538
 539         audit_ipc_obj(ipcp);
 540         requested_mode = (flag >> 6) | (flag >> 3) | flag;
 541         granted_mode = ipcp->mode;
 542         if (uid_eq(euid, ipcp->cuid) ||
 543             uid_eq(euid, ipcp->uid))
 544                 granted_mode >>= 6;
 545         else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
 546                 granted_mode >>= 3;
 547         /* is there some bit set in requested_mode but not in granted_mode? */
 548         if ((requested_mode & ~granted_mode & 0007) &&
 549             !ns_capable(ns->user_ns, CAP_IPC_OWNER))
 550                 return -1;
 551
 552         return security_ipc_permission(ipcp, flag);
 553 }
 554
 555 /*
 556  * Functions to convert between the kern_ipc_perm structure and the
 557  * old/new ipc_perm structures
 558  */
 559
 560 /**
 561  *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
 562  *      @in: kernel permissions
 563  *      @out: new style IPC permissions
 564  *
 565  *      Turn the kernel object @in into a set of permissions descriptions
 566  *      for returning to userspace (@out).
 567  */
 568
 569
 570 void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
 571 {
 572         out->key        = in->key;
 573         out->uid        = from_kuid_munged(current_user_ns(), in->uid);
 574         out->gid        = from_kgid_munged(current_user_ns(), in->gid);
 575         out->cuid       = from_kuid_munged(current_user_ns(), in->cuid);
 576         out->cgid       = from_kgid_munged(current_user_ns(), in->cgid);
 577         out->mode       = in->mode;
 578         out->seq        = in->seq;
 579 }
 580
 581 /**
 582  *      ipc64_perm_to_ipc_perm  -       convert new ipc permissions to old
 583  *      @in: new style IPC permissions
 584  *      @out: old style IPC permissions
 585  *
 586  *      Turn the new style permissions object @in into a compatibility
 587  *      object and store it into the @out pointer.
 588  */
 589
 590 void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
 591 {
 592         out->key        = in->key;
 593         SET_UID(out->uid, in->uid);
 594         SET_GID(out->gid, in->gid);
 595         SET_UID(out->cuid, in->cuid);
 596         SET_GID(out->cgid, in->cgid);
 597         out->mode       = in->mode;
 598         out->seq        = in->seq;
 599 }
 600
 601 /**
 602  * ipc_obtain_object
 603  * @ids: ipc identifier set
 604  * @id: ipc id to look for
 605  *
 606  * Look for an id in the ipc ids idr and return associated ipc object.
 607  *
 608  * Call inside the RCU critical section.
 609  * The ipc object is *not* locked on exit.
 610  */
 611 struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id)
 612 {
 613         struct kern_ipc_perm *out;
 614         int lid = ipcid_to_idx(id);
 615
 616         out = idr_find(&ids->ipcs_idr, lid);
 617         if (!out)
 618                 return ERR_PTR(-EINVAL);
 619
 620         return out;
 621 }
 622
 623 /**
 624  * ipc_lock - Lock an ipc structure without rw_mutex held
 625  * @ids: IPC identifier set
 626  * @id: ipc id to look for
 627  *
 628  * Look for an id in the ipc ids idr and lock the associated ipc object.
 629  *
 630  * The ipc object is locked on successful exit.
 631  */
 632 struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
 633 {
 634         struct kern_ipc_perm *out;
 635
 636         rcu_read_lock();
 637         out = ipc_obtain_object(ids, id);
 638         if (IS_ERR(out))
 639                 goto err1;
 640
 641         spin_lock(&out->lock);
 642
 643         /* ipc_rmid() may have already freed the ID while ipc_lock
 644          * was spinning: here verify that the structure is still valid
 645          */
 646         if (!out->deleted)
 647                 return out;
 648
 649         spin_unlock(&out->lock);
 650         out = ERR_PTR(-EINVAL);
 651 err1:
 652         rcu_read_unlock();
 653         return out;
 654 }
 655
 656 /**
 657  * ipc_obtain_object_check
 658  * @ids: ipc identifier set
 659  * @id: ipc id to look for
 660  *
 661  * Similar to ipc_obtain_object() but also checks
 662  * the ipc object reference counter.
 663  *
 664  * Call inside the RCU critical section.
 665  * The ipc object is *not* locked on exit.
 666  */
 667 struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
 668 {
 669         struct kern_ipc_perm *out = ipc_obtain_object(ids, id);
 670
 671         if (IS_ERR(out))
 672                 goto out;
 673
 674         if (ipc_checkid(out, id))
 675                 return ERR_PTR(-EIDRM);
 676 out:
 677         return out;
 678 }
 679
 680 struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id)
 681 {
 682         struct kern_ipc_perm *out;
 683
 684         out = ipc_lock(ids, id);
 685         if (IS_ERR(out))
 686                 return out;
 687
 688         if (ipc_checkid(out, id)) {
 689                 ipc_unlock(out);
 690                 return ERR_PTR(-EIDRM);
 691         }
 692
 693         return out;
 694 }
 695
 696 /**
 697  * ipcget - Common sys_*get() code
 698  * @ns : namsepace
 699  * @ids : IPC identifier set
 700  * @ops : operations to be called on ipc object creation, permission checks
 701  *        and further checks
 702  * @params : the parameters needed by the previous operations.
 703  *
 704  * Common routine called by sys_msgget(), sys_semget() and sys_shmget().
 705  */
 706 int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
 707                         struct ipc_ops *ops, struct ipc_params *params)
 708 {
 709         if (params->key == IPC_PRIVATE)
 710                 return ipcget_new(ns, ids, ops, params);
 711         else
 712                 return ipcget_public(ns, ids, ops, params);
 713 }
 714
 715 /**
 716  * ipc_update_perm - update the permissions of an IPC.
 717  * @in:  the permission given as input.
 718  * @out: the permission of the ipc to set.
 719  */
 720 int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
 721 {
 722         kuid_t uid = make_kuid(current_user_ns(), in->uid);
 723         kgid_t gid = make_kgid(current_user_ns(), in->gid);
 724         if (!uid_valid(uid) || !gid_valid(gid))
 725                 return -EINVAL;
 726
 727         out->uid = uid;
 728         out->gid = gid;
 729         out->mode = (out->mode & ~S_IRWXUGO)
 730                 | (in->mode & S_IRWXUGO);
 731
 732         return 0;
 733 }
 734
 735 /**
 736  * ipcctl_pre_down_nolock - retrieve an ipc and check permissions for some IPC_XXX cmd
 737  * @ns:  the ipc namespace
 738  * @ids:  the table of ids where to look for the ipc
 739  * @id:   the id of the ipc to retrieve
 740  * @cmd:  the cmd to check
 741  * @perm: the permission to set
 742  * @extra_perm: one extra permission parameter used by msq
 743  *
 744  * This function does some common audit and permissions check for some IPC_XXX
 745  * cmd and is called from semctl_down, shmctl_down and msgctl_down.
 746  * It must be called without any lock held and
 747  *  - retrieves the ipc with the given id in the given table.
 748  *  - performs some audit and permission check, depending on the given cmd
 749  *  - returns a pointer to the ipc object or otherwise, the corresponding error.
 750  *
 751  * Call holding the both the rw_mutex and the rcu read lock.
 752  */
 753 struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
 754                                         struct ipc_ids *ids, int id, int cmd,
 755                                         struct ipc64_perm *perm, int extra_perm)
 756 {
 757         kuid_t euid;
 758         int err = -EPERM;
 759         struct kern_ipc_perm *ipcp;
 760
 761         ipcp = ipc_obtain_object_check(ids, id);
 762         if (IS_ERR(ipcp)) {
 763                 err = PTR_ERR(ipcp);
 764                 goto err;
 765         }
 766
 767         audit_ipc_obj(ipcp);
 768         if (cmd == IPC_SET)
 769                 audit_ipc_set_perm(extra_perm, perm->uid,
 770                                    perm->gid, perm->mode);
 771
 772         euid = current_euid();
 773         if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid)  ||
 774             ns_capable(ns->user_ns, CAP_SYS_ADMIN))
 775                 return ipcp; /* successful lookup */
 776 err:
 777         return ERR_PTR(err);
 778 }
 779
 780 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
 781
 782
 783 /**
 784  *      ipc_parse_version       -       IPC call version
 785  *      @cmd: pointer to command
 786  *
 787  *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
 788  *      The @cmd value is turned from an encoding command and version into
 789  *      just the command code.
 790  */
 791
 792 int ipc_parse_version (int *cmd)
 793 {
 794         if (*cmd & IPC_64) {
 795                 *cmd ^= IPC_64;
 796                 return IPC_64;
 797         } else {
 798                 return IPC_OLD;
 799         }
 800 }
 801
 802 #endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
 803
 804 #ifdef CONFIG_PROC_FS
 805 struct ipc_proc_iter {
 806         struct ipc_namespace *ns;
 807         struct ipc_proc_iface *iface;
 808 };
 809
 810 /*
 811  * This routine locks the ipc structure found at least at position pos.
 812  */
 813 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 814                                               loff_t *new_pos)
 815 {
 816         struct kern_ipc_perm *ipc;
 817         int total, id;
 818
 819         total = 0;
 820         for (id = 0; id < pos && total < ids->in_use; id++) {
 821                 ipc = idr_find(&ids->ipcs_idr, id);
 822                 if (ipc != NULL)
 823                         total++;
 824         }
 825
 826         if (total >= ids->in_use)
 827                 return NULL;
 828
 829         for ( ; pos < IPCMNI; pos++) {
 830                 ipc = idr_find(&ids->ipcs_idr, pos);
 831                 if (ipc != NULL) {
 832                         *new_pos = pos + 1;
 833                         ipc_lock_by_ptr(ipc);
 834                         return ipc;
 835                 }
 836         }
 837
 838         /* Out of range - return NULL to terminate iteration */
 839         return NULL;
 840 }
 841
 842 static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
 843 {
 844         struct ipc_proc_iter *iter = s->private;
 845         struct ipc_proc_iface *iface = iter->iface;
 846         struct kern_ipc_perm *ipc = it;
 847
 848         /* If we had an ipc id locked before, unlock it */
 849         if (ipc && ipc != SEQ_START_TOKEN)
 850                 ipc_unlock(ipc);
 851
 852         return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
 853 }
 854
 855 /*
 856  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
 857  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
 858  */
 859 static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
 860 {
 861         struct ipc_proc_iter *iter = s->private;
 862         struct ipc_proc_iface *iface = iter->iface;
 863         struct ipc_ids *ids;
 864
 865         ids = &iter->ns->ids[iface->ids];
 866
 867         /*
 868          * Take the lock - this will be released by the corresponding
 869          * call to stop().
 870          */
 871         down_read(&ids->rw_mutex);
 872
 873         /* pos < 0 is invalid */
 874         if (*pos < 0)
 875                 return NULL;
 876
 877         /* pos == 0 means header */
 878         if (*pos == 0)
 879                 return SEQ_START_TOKEN;
 880
 881         /* Find the (pos-1)th ipc */
 882         return sysvipc_find_ipc(ids, *pos - 1, pos);
 883 }
 884
 885 static void sysvipc_proc_stop(struct seq_file *s, void *it)
 886 {
 887         struct kern_ipc_perm *ipc = it;
 888         struct ipc_proc_iter *iter = s->private;
 889         struct ipc_proc_iface *iface = iter->iface;
 890         struct ipc_ids *ids;
 891
 892         /* If we had a locked structure, release it */
 893         if (ipc && ipc != SEQ_START_TOKEN)
 894                 ipc_unlock(ipc);
 895
 896         ids = &iter->ns->ids[iface->ids];
 897         /* Release the lock we took in start() */
 898         up_read(&ids->rw_mutex);
 899 }
 900
 901 static int sysvipc_proc_show(struct seq_file *s, void *it)
 902 {
 903         struct ipc_proc_iter *iter = s->private;
 904         struct ipc_proc_iface *iface = iter->iface;
 905
 906         if (it == SEQ_START_TOKEN)
 907                 return seq_puts(s, iface->header);
 908
 909         return iface->show(s, it);
 910 }
 911
 912 static const struct seq_operations sysvipc_proc_seqops = {
 913         .start = sysvipc_proc_start,
 914         .stop  = sysvipc_proc_stop,
 915         .next  = sysvipc_proc_next,
 916         .show  = sysvipc_proc_show,
 917 };
 918
 919 static int sysvipc_proc_open(struct inode *inode, struct file *file)
 920 {
 921         int ret;
 922         struct seq_file *seq;
 923         struct ipc_proc_iter *iter;
 924
 925         ret = -ENOMEM;
 926         iter = kmalloc(sizeof(*iter), GFP_KERNEL);
 927         if (!iter)
 928                 goto out;
 929
 930         ret = seq_open(file, &sysvipc_proc_seqops);
 931         if (ret)
 932                 goto out_kfree;
 933
 934         seq = file->private_data;
 935         seq->private = iter;
 936
 937         iter->iface = PDE_DATA(inode);
 938         iter->ns    = get_ipc_ns(current->nsproxy->ipc_ns);
 939 out:
 940         return ret;
 941 out_kfree:
 942         kfree(iter);
 943         goto out;
 944 }
 945
 946 static int sysvipc_proc_release(struct inode *inode, struct file *file)
 947 {
 948         struct seq_file *seq = file->private_data;
 949         struct ipc_proc_iter *iter = seq->private;
 950         put_ipc_ns(iter->ns);
 951         return seq_release_private(inode, file);
 952 }
 953
 954 static const struct file_operations sysvipc_proc_fops = {
 955         .open    = sysvipc_proc_open,
 956         .read    = seq_read,
 957         .llseek  = seq_lseek,
 958         .release = sysvipc_proc_release,
 959 };
 960 #endif /* CONFIG_PROC_FS */