ipc/shm.c

   1 /*
   2  * linux/ipc/shm.c
   3  * Copyright (C) 1992, 1993 Krishna Balasubramanian
   4  *       Many improvements/fixes by Bruno Haible.
   5  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
   6  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
   7  *
   8  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
   9  * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
  10  * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
  11  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
  12  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
  13  * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
  14  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
  15  *
  16  * support for audit of ipc object properties and permission changes
  17  * Dustin Kirkland <dustin.kirkland@us.ibm.com>
  18  *
  19  * namespaces support
  20  * OpenVZ, SWsoft Inc.
  21  * Pavel Emelianov <xemul@openvz.org>
  22  *
  23  * Better ipc lock (kern_ipc_perm.lock) handling
  24  * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
  25  */
  26
  27 #include <linux/slab.h>
  28 #include <linux/mm.h>
  29 #include <linux/hugetlb.h>
  30 #include <linux/shm.h>
  31 #include <linux/init.h>
  32 #include <linux/file.h>
  33 #include <linux/mman.h>
  34 #include <linux/shmem_fs.h>
  35 #include <linux/security.h>
  36 #include <linux/syscalls.h>
  37 #include <linux/audit.h>
  38 #include <linux/capability.h>
  39 #include <linux/ptrace.h>
  40 #include <linux/seq_file.h>
  41 #include <linux/rwsem.h>
  42 #include <linux/nsproxy.h>
  43 #include <linux/mount.h>
  44 #include <linux/ipc_namespace.h>
  45
  46 #include <linux/uaccess.h>
  47
  48 #include "util.h"
  49
  50 struct shm_file_data {
  51         int id;
  52         struct ipc_namespace *ns;
  53         struct file *file;
  54         const struct vm_operations_struct *vm_ops;
  55 };
  56
  57 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  58
  59 static const struct file_operations shm_file_operations;
  60 static const struct vm_operations_struct shm_vm_ops;
  61
  62 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
  63
  64 #define shm_unlock(shp)                 \
  65         ipc_unlock(&(shp)->shm_perm)
  66
  67 static int newseg(struct ipc_namespace *, struct ipc_params *);
  68 static void shm_open(struct vm_area_struct *vma);
  69 static void shm_close(struct vm_area_struct *vma);
  70 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
  71 #ifdef CONFIG_PROC_FS
  72 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  73 #endif
  74
  75 void shm_init_ns(struct ipc_namespace *ns)
  76 {
  77         ns->shm_ctlmax = SHMMAX;
  78         ns->shm_ctlall = SHMALL;
  79         ns->shm_ctlmni = SHMMNI;
  80         ns->shm_rmid_forced = 0;
  81         ns->shm_tot = 0;
  82         ipc_init_ids(&shm_ids(ns));
  83 }
  84
  85 /*
  86  * Called with shm_ids.rwsem (writer) and the shp structure locked.
  87  * Only shm_ids.rwsem remains locked on exit.
  88  */
  89 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
  90 {
  91         struct shmid_kernel *shp;
  92
  93         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
  94
  95         if (shp->shm_nattch) {
  96                 shp->shm_perm.mode |= SHM_DEST;
  97                 /* Do not find it any more */
  98                 shp->shm_perm.key = IPC_PRIVATE;
  99                 shm_unlock(shp);
 100         } else
 101                 shm_destroy(ns, shp);
 102 }
 103
 104 #ifdef CONFIG_IPC_NS
 105 void shm_exit_ns(struct ipc_namespace *ns)
 106 {
 107         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 108         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 109 }
 110 #endif
 111
 112 static int __init ipc_ns_init(void)
 113 {
 114         shm_init_ns(&init_ipc_ns);
 115         return 0;
 116 }
 117
 118 pure_initcall(ipc_ns_init);
 119
 120 void __init shm_init(void)
 121 {
 122         ipc_init_proc_interface("sysvipc/shm",
 123 #if BITS_PER_LONG <= 32
 124                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 125 #else
 126                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 127 #endif
 128                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 129 }
 130
 131 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 132 {
 133         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 134
 135         if (IS_ERR(ipcp))
 136                 return ERR_CAST(ipcp);
 137
 138         return container_of(ipcp, struct shmid_kernel, shm_perm);
 139 }
 140
 141 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 142 {
 143         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 144
 145         if (IS_ERR(ipcp))
 146                 return ERR_CAST(ipcp);
 147
 148         return container_of(ipcp, struct shmid_kernel, shm_perm);
 149 }
 150
 151 /*
 152  * shm_lock_(check_) routines are called in the paths where the rwsem
 153  * is not necessarily held.
 154  */
 155 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 156 {
 157         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 158
 159         /*
 160          * Callers of shm_lock() must validate the status of the returned ipc
 161          * object pointer (as returned by ipc_lock()), and error out as
 162          * appropriate.
 163          */
 164         if (IS_ERR(ipcp))
 165                 return (void *)ipcp;
 166         return container_of(ipcp, struct shmid_kernel, shm_perm);
 167 }
 168
 169 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 170 {
 171         rcu_read_lock();
 172         ipc_lock_object(&ipcp->shm_perm);
 173 }
 174
 175 static void __shm_free(struct shmid_kernel *shp)
 176 {
 177         kvfree(shp);
 178 }
 179
 180 static void shm_rcu_free(struct rcu_head *head)
 181 {
 182         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
 183                                                         rcu);
 184         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
 185                                                         shm_perm);
 186         security_shm_free(shp);
 187         __shm_free(shp);
 188 }
 189
 190 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 191 {
 192         list_del(&s->shm_clist);
 193         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 194 }
 195
 196
 197 static int __shm_open(struct vm_area_struct *vma)
 198 {
 199         struct file *file = vma->vm_file;
 200         struct shm_file_data *sfd = shm_file_data(file);
 201         struct shmid_kernel *shp;
 202
 203         shp = shm_lock(sfd->ns, sfd->id);
 204
 205         if (IS_ERR(shp))
 206                 return PTR_ERR(shp);
 207
 208         shp->shm_atim = get_seconds();
 209         shp->shm_lprid = task_tgid_vnr(current);
 210         shp->shm_nattch++;
 211         shm_unlock(shp);
 212         return 0;
 213 }
 214
 215 /* This is called by fork, once for every shm attach. */
 216 static void shm_open(struct vm_area_struct *vma)
 217 {
 218         int err = __shm_open(vma);
 219         /*
 220          * We raced in the idr lookup or with shm_destroy().
 221          * Either way, the ID is busted.
 222          */
 223         WARN_ON_ONCE(err);
 224 }
 225
 226 /*
 227  * shm_destroy - free the struct shmid_kernel
 228  *
 229  * @ns: namespace
 230  * @shp: struct to free
 231  *
 232  * It has to be called with shp and shm_ids.rwsem (writer) locked,
 233  * but returns with shp unlocked and freed.
 234  */
 235 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 236 {
 237         struct file *shm_file;
 238
 239         shm_file = shp->shm_file;
 240         shp->shm_file = NULL;
 241         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 242         shm_rmid(ns, shp);
 243         shm_unlock(shp);
 244         if (!is_file_hugepages(shm_file))
 245                 shmem_lock(shm_file, 0, shp->mlock_user);
 246         else if (shp->mlock_user)
 247                 user_shm_unlock(i_size_read(file_inode(shm_file)),
 248                                 shp->mlock_user);
 249         fput(shm_file);
 250         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 251 }
 252
 253 /*
 254  * shm_may_destroy - identifies whether shm segment should be destroyed now
 255  *
 256  * Returns true if and only if there are no active users of the segment and
 257  * one of the following is true:
 258  *
 259  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 260  *
 261  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 262  */
 263 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 264 {
 265         return (shp->shm_nattch == 0) &&
 266                (ns->shm_rmid_forced ||
 267                 (shp->shm_perm.mode & SHM_DEST));
 268 }
 269
 270 /*
 271  * remove the attach descriptor vma.
 272  * free memory for segment if it is marked destroyed.
 273  * The descriptor has already been removed from the current->mm->mmap list
 274  * and will later be kfree()d.
 275  */
 276 static void shm_close(struct vm_area_struct *vma)
 277 {
 278         struct file *file = vma->vm_file;
 279         struct shm_file_data *sfd = shm_file_data(file);
 280         struct shmid_kernel *shp;
 281         struct ipc_namespace *ns = sfd->ns;
 282
 283         down_write(&shm_ids(ns).rwsem);
 284         /* remove from the list of attaches of the shm segment */
 285         shp = shm_lock(ns, sfd->id);
 286
 287         /*
 288          * We raced in the idr lookup or with shm_destroy().
 289          * Either way, the ID is busted.
 290          */
 291         if (WARN_ON_ONCE(IS_ERR(shp)))
 292                 goto done; /* no-op */
 293
 294         shp->shm_lprid = task_tgid_vnr(current);
 295         shp->shm_dtim = get_seconds();
 296         shp->shm_nattch--;
 297         if (shm_may_destroy(ns, shp))
 298                 shm_destroy(ns, shp);
 299         else
 300                 shm_unlock(shp);
 301 done:
 302         up_write(&shm_ids(ns).rwsem);
 303 }
 304
 305 /* Called with ns->shm_ids(ns).rwsem locked */
 306 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 307 {
 308         struct ipc_namespace *ns = data;
 309         struct kern_ipc_perm *ipcp = p;
 310         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 311
 312         /*
 313          * We want to destroy segments without users and with already
 314          * exit'ed originating process.
 315          *
 316          * As shp->* are changed under rwsem, it's safe to skip shp locking.
 317          */
 318         if (shp->shm_creator != NULL)
 319                 return 0;
 320
 321         if (shm_may_destroy(ns, shp)) {
 322                 shm_lock_by_ptr(shp);
 323                 shm_destroy(ns, shp);
 324         }
 325         return 0;
 326 }
 327
 328 void shm_destroy_orphaned(struct ipc_namespace *ns)
 329 {
 330         down_write(&shm_ids(ns).rwsem);
 331         if (shm_ids(ns).in_use)
 332                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 333         up_write(&shm_ids(ns).rwsem);
 334 }
 335
 336 /* Locking assumes this will only be called with task == current */
 337 void exit_shm(struct task_struct *task)
 338 {
 339         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 340         struct shmid_kernel *shp, *n;
 341
 342         if (list_empty(&task->sysvshm.shm_clist))
 343                 return;
 344
 345         /*
 346          * If kernel.shm_rmid_forced is not set then only keep track of
 347          * which shmids are orphaned, so that a later set of the sysctl
 348          * can clean them up.
 349          */
 350         if (!ns->shm_rmid_forced) {
 351                 down_read(&shm_ids(ns).rwsem);
 352                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
 353                         shp->shm_creator = NULL;
 354                 /*
 355                  * Only under read lock but we are only called on current
 356                  * so no entry on the list will be shared.
 357                  */
 358                 list_del(&task->sysvshm.shm_clist);
 359                 up_read(&shm_ids(ns).rwsem);
 360                 return;
 361         }
 362
 363         /*
 364          * Destroy all already created segments, that were not yet mapped,
 365          * and mark any mapped as orphan to cover the sysctl toggling.
 366          * Destroy is skipped if shm_may_destroy() returns false.
 367          */
 368         down_write(&shm_ids(ns).rwsem);
 369         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
 370                 shp->shm_creator = NULL;
 371
 372                 if (shm_may_destroy(ns, shp)) {
 373                         shm_lock_by_ptr(shp);
 374                         shm_destroy(ns, shp);
 375                 }
 376         }
 377
 378         /* Remove the list head from any segments still attached. */
 379         list_del(&task->sysvshm.shm_clist);
 380         up_write(&shm_ids(ns).rwsem);
 381 }
 382
 383 static int shm_fault(struct vm_fault *vmf)
 384 {
 385         struct file *file = vmf->vma->vm_file;
 386         struct shm_file_data *sfd = shm_file_data(file);
 387
 388         return sfd->vm_ops->fault(vmf);
 389 }
 390
 391 #ifdef CONFIG_NUMA
 392 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 393 {
 394         struct file *file = vma->vm_file;
 395         struct shm_file_data *sfd = shm_file_data(file);
 396         int err = 0;
 397
 398         if (sfd->vm_ops->set_policy)
 399                 err = sfd->vm_ops->set_policy(vma, new);
 400         return err;
 401 }
 402
 403 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 404                                         unsigned long addr)
 405 {
 406         struct file *file = vma->vm_file;
 407         struct shm_file_data *sfd = shm_file_data(file);
 408         struct mempolicy *pol = NULL;
 409
 410         if (sfd->vm_ops->get_policy)
 411                 pol = sfd->vm_ops->get_policy(vma, addr);
 412         else if (vma->vm_policy)
 413                 pol = vma->vm_policy;
 414
 415         return pol;
 416 }
 417 #endif
 418
 419 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 420 {
 421         struct shm_file_data *sfd = shm_file_data(file);
 422         int ret;
 423
 424         /*
 425          * In case of remap_file_pages() emulation, the file can represent
 426          * removed IPC ID: propogate shm_lock() error to caller.
 427          */
 428         ret = __shm_open(vma);
 429         if (ret)
 430                 return ret;
 431
 432         ret = call_mmap(sfd->file, vma);
 433         if (ret) {
 434                 shm_close(vma);
 435                 return ret;
 436         }
 437         sfd->vm_ops = vma->vm_ops;
 438 #ifdef CONFIG_MMU
 439         WARN_ON(!sfd->vm_ops->fault);
 440 #endif
 441         vma->vm_ops = &shm_vm_ops;
 442         return 0;
 443 }
 444
 445 static int shm_release(struct inode *ino, struct file *file)
 446 {
 447         struct shm_file_data *sfd = shm_file_data(file);
 448
 449         put_ipc_ns(sfd->ns);
 450         shm_file_data(file) = NULL;
 451         kfree(sfd);
 452         return 0;
 453 }
 454
 455 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 456 {
 457         struct shm_file_data *sfd = shm_file_data(file);
 458
 459         if (!sfd->file->f_op->fsync)
 460                 return -EINVAL;
 461         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 462 }
 463
 464 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 465                           loff_t len)
 466 {
 467         struct shm_file_data *sfd = shm_file_data(file);
 468
 469         if (!sfd->file->f_op->fallocate)
 470                 return -EOPNOTSUPP;
 471         return sfd->file->f_op->fallocate(file, mode, offset, len);
 472 }
 473
 474 static unsigned long shm_get_unmapped_area(struct file *file,
 475         unsigned long addr, unsigned long len, unsigned long pgoff,
 476         unsigned long flags)
 477 {
 478         struct shm_file_data *sfd = shm_file_data(file);
 479
 480         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 481                                                 pgoff, flags);
 482 }
 483
 484 static const struct file_operations shm_file_operations = {
 485         .mmap           = shm_mmap,
 486         .fsync          = shm_fsync,
 487         .release        = shm_release,
 488         .get_unmapped_area      = shm_get_unmapped_area,
 489         .llseek         = noop_llseek,
 490         .fallocate      = shm_fallocate,
 491 };
 492
 493 /*
 494  * shm_file_operations_huge is now identical to shm_file_operations,
 495  * but we keep it distinct for the sake of is_file_shm_hugepages().
 496  */
 497 static const struct file_operations shm_file_operations_huge = {
 498         .mmap           = shm_mmap,
 499         .fsync          = shm_fsync,
 500         .release        = shm_release,
 501         .get_unmapped_area      = shm_get_unmapped_area,
 502         .llseek         = noop_llseek,
 503         .fallocate      = shm_fallocate,
 504 };
 505
 506 bool is_file_shm_hugepages(struct file *file)
 507 {
 508         return file->f_op == &shm_file_operations_huge;
 509 }
 510
 511 static const struct vm_operations_struct shm_vm_ops = {
 512         .open   = shm_open,     /* callback for a new vm-area open */
 513         .close  = shm_close,    /* callback for when the vm-area is released */
 514         .fault  = shm_fault,
 515 #if defined(CONFIG_NUMA)
 516         .set_policy = shm_set_policy,
 517         .get_policy = shm_get_policy,
 518 #endif
 519 };
 520
 521 static struct shmid_kernel *shm_alloc(void)
 522 {
 523         struct shmid_kernel *shp;
 524
 525         shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
 526         if (unlikely(!shp))
 527                 return NULL;
 528
 529         atomic_set(&shp->shm_perm.refcount, 1);
 530
 531         return shp;
 532 }
 533
 534 /**
 535  * newseg - Create a new shared memory segment
 536  * @ns: namespace
 537  * @params: ptr to the structure that contains key, size and shmflg
 538  *
 539  * Called with shm_ids.rwsem held as a writer.
 540  */
 541 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 542 {
 543         key_t key = params->key;
 544         int shmflg = params->flg;
 545         size_t size = params->u.size;
 546         int error;
 547         struct shmid_kernel *shp;
 548         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 549         struct file *file;
 550         char name[13];
 551         int id;
 552         vm_flags_t acctflag = 0;
 553
 554         if (size < SHMMIN || size > ns->shm_ctlmax)
 555                 return -EINVAL;
 556
 557         if (numpages << PAGE_SHIFT < size)
 558                 return -ENOSPC;
 559
 560         if (ns->shm_tot + numpages < ns->shm_tot ||
 561                         ns->shm_tot + numpages > ns->shm_ctlall)
 562                 return -ENOSPC;
 563
 564         shp = shm_alloc();
 565         if (!shp)
 566                 return -ENOMEM;
 567
 568         shp->shm_perm.key = key;
 569         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 570         shp->mlock_user = NULL;
 571
 572         shp->shm_perm.security = NULL;
 573         error = security_shm_alloc(shp);
 574         if (error) {
 575                 __shm_free(shp);
 576                 return error;
 577         }
 578
 579         sprintf(name, "SYSV%08x", key);
 580         if (shmflg & SHM_HUGETLB) {
 581                 struct hstate *hs;
 582                 size_t hugesize;
 583
 584                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 585                 if (!hs) {
 586                         error = -EINVAL;
 587                         goto no_file;
 588                 }
 589                 hugesize = ALIGN(size, huge_page_size(hs));
 590
 591                 /* hugetlb_file_setup applies strict accounting */
 592                 if (shmflg & SHM_NORESERVE)
 593                         acctflag = VM_NORESERVE;
 594                 file = hugetlb_file_setup(name, hugesize, acctflag,
 595                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
 596                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 597         } else {
 598                 /*
 599                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 600                  * if it's asked for.
 601                  */
 602                 if  ((shmflg & SHM_NORESERVE) &&
 603                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 604                         acctflag = VM_NORESERVE;
 605                 file = shmem_kernel_file_setup(name, size, acctflag);
 606         }
 607         error = PTR_ERR(file);
 608         if (IS_ERR(file))
 609                 goto no_file;
 610
 611         shp->shm_cprid = task_tgid_vnr(current);
 612         shp->shm_lprid = 0;
 613         shp->shm_atim = shp->shm_dtim = 0;
 614         shp->shm_ctim = get_seconds();
 615         shp->shm_segsz = size;
 616         shp->shm_nattch = 0;
 617         shp->shm_file = file;
 618         shp->shm_creator = current;
 619
 620         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 621         if (id < 0) {
 622                 error = id;
 623                 goto no_id;
 624         }
 625
 626         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 627
 628         /*
 629          * shmid gets reported as "inode#" in /proc/pid/maps.
 630          * proc-ps tools use this. Changing this will break them.
 631          */
 632         file_inode(file)->i_ino = shp->shm_perm.id;
 633
 634         ns->shm_tot += numpages;
 635         error = shp->shm_perm.id;
 636
 637         ipc_unlock_object(&shp->shm_perm);
 638         rcu_read_unlock();
 639         return error;
 640
 641 no_id:
 642         if (is_file_hugepages(file) && shp->mlock_user)
 643                 user_shm_unlock(size, shp->mlock_user);
 644         fput(file);
 645 no_file:
 646         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 647         return error;
 648 }
 649
 650 /*
 651  * Called with shm_ids.rwsem and ipcp locked.
 652  */
 653 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 654 {
 655         struct shmid_kernel *shp;
 656
 657         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 658         return security_shm_associate(shp, shmflg);
 659 }
 660
 661 /*
 662  * Called with shm_ids.rwsem and ipcp locked.
 663  */
 664 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 665                                 struct ipc_params *params)
 666 {
 667         struct shmid_kernel *shp;
 668
 669         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 670         if (shp->shm_segsz < params->u.size)
 671                 return -EINVAL;
 672
 673         return 0;
 674 }
 675
 676 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 677 {
 678         struct ipc_namespace *ns;
 679         static const struct ipc_ops shm_ops = {
 680                 .getnew = newseg,
 681                 .associate = shm_security,
 682                 .more_checks = shm_more_checks,
 683         };
 684         struct ipc_params shm_params;
 685
 686         ns = current->nsproxy->ipc_ns;
 687
 688         shm_params.key = key;
 689         shm_params.flg = shmflg;
 690         shm_params.u.size = size;
 691
 692         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 693 }
 694
 695 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 696 {
 697         switch (version) {
 698         case IPC_64:
 699                 return copy_to_user(buf, in, sizeof(*in));
 700         case IPC_OLD:
 701             {
 702                 struct shmid_ds out;
 703
 704                 memset(&out, 0, sizeof(out));
 705                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 706                 out.shm_segsz   = in->shm_segsz;
 707                 out.shm_atime   = in->shm_atime;
 708                 out.shm_dtime   = in->shm_dtime;
 709                 out.shm_ctime   = in->shm_ctime;
 710                 out.shm_cpid    = in->shm_cpid;
 711                 out.shm_lpid    = in->shm_lpid;
 712                 out.shm_nattch  = in->shm_nattch;
 713
 714                 return copy_to_user(buf, &out, sizeof(out));
 715             }
 716         default:
 717                 return -EINVAL;
 718         }
 719 }
 720
 721 static inline unsigned long
 722 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 723 {
 724         switch (version) {
 725         case IPC_64:
 726                 if (copy_from_user(out, buf, sizeof(*out)))
 727                         return -EFAULT;
 728                 return 0;
 729         case IPC_OLD:
 730             {
 731                 struct shmid_ds tbuf_old;
 732
 733                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 734                         return -EFAULT;
 735
 736                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 737                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 738                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 739
 740                 return 0;
 741             }
 742         default:
 743                 return -EINVAL;
 744         }
 745 }
 746
 747 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 748 {
 749         switch (version) {
 750         case IPC_64:
 751                 return copy_to_user(buf, in, sizeof(*in));
 752         case IPC_OLD:
 753             {
 754                 struct shminfo out;
 755
 756                 if (in->shmmax > INT_MAX)
 757                         out.shmmax = INT_MAX;
 758                 else
 759                         out.shmmax = (int)in->shmmax;
 760
 761                 out.shmmin      = in->shmmin;
 762                 out.shmmni      = in->shmmni;
 763                 out.shmseg      = in->shmseg;
 764                 out.shmall      = in->shmall;
 765
 766                 return copy_to_user(buf, &out, sizeof(out));
 767             }
 768         default:
 769                 return -EINVAL;
 770         }
 771 }
 772
 773 /*
 774  * Calculate and add used RSS and swap pages of a shm.
 775  * Called with shm_ids.rwsem held as a reader
 776  */
 777 static void shm_add_rss_swap(struct shmid_kernel *shp,
 778         unsigned long *rss_add, unsigned long *swp_add)
 779 {
 780         struct inode *inode;
 781
 782         inode = file_inode(shp->shm_file);
 783
 784         if (is_file_hugepages(shp->shm_file)) {
 785                 struct address_space *mapping = inode->i_mapping;
 786                 struct hstate *h = hstate_file(shp->shm_file);
 787                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 788         } else {
 789 #ifdef CONFIG_SHMEM
 790                 struct shmem_inode_info *info = SHMEM_I(inode);
 791
 792                 spin_lock_irq(&info->lock);
 793                 *rss_add += inode->i_mapping->nrpages;
 794                 *swp_add += info->swapped;
 795                 spin_unlock_irq(&info->lock);
 796 #else
 797                 *rss_add += inode->i_mapping->nrpages;
 798 #endif
 799         }
 800 }
 801
 802 /*
 803  * Called with shm_ids.rwsem held as a reader
 804  */
 805 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 806                 unsigned long *swp)
 807 {
 808         int next_id;
 809         int total, in_use;
 810
 811         *rss = 0;
 812         *swp = 0;
 813
 814         in_use = shm_ids(ns).in_use;
 815
 816         for (total = 0, next_id = 0; total < in_use; next_id++) {
 817                 struct kern_ipc_perm *ipc;
 818                 struct shmid_kernel *shp;
 819
 820                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 821                 if (ipc == NULL)
 822                         continue;
 823                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 824
 825                 shm_add_rss_swap(shp, rss, swp);
 826
 827                 total++;
 828         }
 829 }
 830
 831 /*
 832  * This function handles some shmctl commands which require the rwsem
 833  * to be held in write mode.
 834  * NOTE: no locks must be held, the rwsem is taken inside this function.
 835  */
 836 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 837                        struct shmid_ds __user *buf, int version)
 838 {
 839         struct kern_ipc_perm *ipcp;
 840         struct shmid64_ds shmid64;
 841         struct shmid_kernel *shp;
 842         int err;
 843
 844         if (cmd == IPC_SET) {
 845                 if (copy_shmid_from_user(&shmid64, buf, version))
 846                         return -EFAULT;
 847         }
 848
 849         down_write(&shm_ids(ns).rwsem);
 850         rcu_read_lock();
 851
 852         ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
 853                                       &shmid64.shm_perm, 0);
 854         if (IS_ERR(ipcp)) {
 855                 err = PTR_ERR(ipcp);
 856                 goto out_unlock1;
 857         }
 858
 859         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 860
 861         err = security_shm_shmctl(shp, cmd);
 862         if (err)
 863                 goto out_unlock1;
 864
 865         switch (cmd) {
 866         case IPC_RMID:
 867                 ipc_lock_object(&shp->shm_perm);
 868                 /* do_shm_rmid unlocks the ipc object and rcu */
 869                 do_shm_rmid(ns, ipcp);
 870                 goto out_up;
 871         case IPC_SET:
 872                 ipc_lock_object(&shp->shm_perm);
 873                 err = ipc_update_perm(&shmid64.shm_perm, ipcp);
 874                 if (err)
 875                         goto out_unlock0;
 876                 shp->shm_ctim = get_seconds();
 877                 break;
 878         default:
 879                 err = -EINVAL;
 880                 goto out_unlock1;
 881         }
 882
 883 out_unlock0:
 884         ipc_unlock_object(&shp->shm_perm);
 885 out_unlock1:
 886         rcu_read_unlock();
 887 out_up:
 888         up_write(&shm_ids(ns).rwsem);
 889         return err;
 890 }
 891
 892 static int shmctl_nolock(struct ipc_namespace *ns, int shmid,
 893                          int cmd, int version, void __user *buf)
 894 {
 895         int err;
 896         struct shmid_kernel *shp;
 897
 898         /* preliminary security checks for *_INFO */
 899         if (cmd == IPC_INFO || cmd == SHM_INFO) {
 900                 err = security_shm_shmctl(NULL, cmd);
 901                 if (err)
 902                         return err;
 903         }
 904
 905         switch (cmd) {
 906         case IPC_INFO:
 907         {
 908                 struct shminfo64 shminfo;
 909
 910                 memset(&shminfo, 0, sizeof(shminfo));
 911                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 912                 shminfo.shmmax = ns->shm_ctlmax;
 913                 shminfo.shmall = ns->shm_ctlall;
 914
 915                 shminfo.shmmin = SHMMIN;
 916                 if (copy_shminfo_to_user(buf, &shminfo, version))
 917                         return -EFAULT;
 918
 919                 down_read(&shm_ids(ns).rwsem);
 920                 err = ipc_get_maxid(&shm_ids(ns));
 921                 up_read(&shm_ids(ns).rwsem);
 922
 923                 if (err < 0)
 924                         err = 0;
 925                 goto out;
 926         }
 927         case SHM_INFO:
 928         {
 929                 struct shm_info shm_info;
 930
 931                 memset(&shm_info, 0, sizeof(shm_info));
 932                 down_read(&shm_ids(ns).rwsem);
 933                 shm_info.used_ids = shm_ids(ns).in_use;
 934                 shm_get_stat(ns, &shm_info.shm_rss, &shm_info.shm_swp);
 935                 shm_info.shm_tot = ns->shm_tot;
 936                 shm_info.swap_attempts = 0;
 937                 shm_info.swap_successes = 0;
 938                 err = ipc_get_maxid(&shm_ids(ns));
 939                 up_read(&shm_ids(ns).rwsem);
 940                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 941                         err = -EFAULT;
 942                         goto out;
 943                 }
 944
 945                 err = err < 0 ? 0 : err;
 946                 goto out;
 947         }
 948         case SHM_STAT:
 949         case IPC_STAT:
 950         {
 951                 struct shmid64_ds tbuf;
 952                 int result;
 953
 954                 rcu_read_lock();
 955                 if (cmd == SHM_STAT) {
 956                         shp = shm_obtain_object(ns, shmid);
 957                         if (IS_ERR(shp)) {
 958                                 err = PTR_ERR(shp);
 959                                 goto out_unlock;
 960                         }
 961                         result = shp->shm_perm.id;
 962                 } else {
 963                         shp = shm_obtain_object_check(ns, shmid);
 964                         if (IS_ERR(shp)) {
 965                                 err = PTR_ERR(shp);
 966                                 goto out_unlock;
 967                         }
 968                         result = 0;
 969                 }
 970
 971                 err = -EACCES;
 972                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 973                         goto out_unlock;
 974
 975                 err = security_shm_shmctl(shp, cmd);
 976                 if (err)
 977                         goto out_unlock;
 978
 979                 memset(&tbuf, 0, sizeof(tbuf));
 980                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 981                 tbuf.shm_segsz  = shp->shm_segsz;
 982                 tbuf.shm_atime  = shp->shm_atim;
 983                 tbuf.shm_dtime  = shp->shm_dtim;
 984                 tbuf.shm_ctime  = shp->shm_ctim;
 985                 tbuf.shm_cpid   = shp->shm_cprid;
 986                 tbuf.shm_lpid   = shp->shm_lprid;
 987                 tbuf.shm_nattch = shp->shm_nattch;
 988                 rcu_read_unlock();
 989
 990                 if (copy_shmid_to_user(buf, &tbuf, version))
 991                         err = -EFAULT;
 992                 else
 993                         err = result;
 994                 goto out;
 995         }
 996         default:
 997                 return -EINVAL;
 998         }
 999
1000 out_unlock:
1001         rcu_read_unlock();
1002 out:
1003         return err;
1004 }
1005
1006 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1007 {
1008         struct shmid_kernel *shp;
1009         int err, version;
1010         struct ipc_namespace *ns;
1011
1012         if (cmd < 0 || shmid < 0)
1013                 return -EINVAL;
1014
1015         version = ipc_parse_version(&cmd);
1016         ns = current->nsproxy->ipc_ns;
1017
1018         switch (cmd) {
1019         case IPC_INFO:
1020         case SHM_INFO:
1021         case SHM_STAT:
1022         case IPC_STAT:
1023                 return shmctl_nolock(ns, shmid, cmd, version, buf);
1024         case IPC_RMID:
1025         case IPC_SET:
1026                 return shmctl_down(ns, shmid, cmd, buf, version);
1027         case SHM_LOCK:
1028         case SHM_UNLOCK:
1029         {
1030                 struct file *shm_file;
1031
1032                 rcu_read_lock();
1033                 shp = shm_obtain_object_check(ns, shmid);
1034                 if (IS_ERR(shp)) {
1035                         err = PTR_ERR(shp);
1036                         goto out_unlock1;
1037                 }
1038
1039                 audit_ipc_obj(&(shp->shm_perm));
1040                 err = security_shm_shmctl(shp, cmd);
1041                 if (err)
1042                         goto out_unlock1;
1043
1044                 ipc_lock_object(&shp->shm_perm);
1045
1046                 /* check if shm_destroy() is tearing down shp */
1047                 if (!ipc_valid_object(&shp->shm_perm)) {
1048                         err = -EIDRM;
1049                         goto out_unlock0;
1050                 }
1051
1052                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1053                         kuid_t euid = current_euid();
1054
1055                         if (!uid_eq(euid, shp->shm_perm.uid) &&
1056                             !uid_eq(euid, shp->shm_perm.cuid)) {
1057                                 err = -EPERM;
1058                                 goto out_unlock0;
1059                         }
1060                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1061                                 err = -EPERM;
1062                                 goto out_unlock0;
1063                         }
1064                 }
1065
1066                 shm_file = shp->shm_file;
1067                 if (is_file_hugepages(shm_file))
1068                         goto out_unlock0;
1069
1070                 if (cmd == SHM_LOCK) {
1071                         struct user_struct *user = current_user();
1072
1073                         err = shmem_lock(shm_file, 1, user);
1074                         if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1075                                 shp->shm_perm.mode |= SHM_LOCKED;
1076                                 shp->mlock_user = user;
1077                         }
1078                         goto out_unlock0;
1079                 }
1080
1081                 /* SHM_UNLOCK */
1082                 if (!(shp->shm_perm.mode & SHM_LOCKED))
1083                         goto out_unlock0;
1084                 shmem_lock(shm_file, 0, shp->mlock_user);
1085                 shp->shm_perm.mode &= ~SHM_LOCKED;
1086                 shp->mlock_user = NULL;
1087                 get_file(shm_file);
1088                 ipc_unlock_object(&shp->shm_perm);
1089                 rcu_read_unlock();
1090                 shmem_unlock_mapping(shm_file->f_mapping);
1091
1092                 fput(shm_file);
1093                 return err;
1094         }
1095         default:
1096                 return -EINVAL;
1097         }
1098
1099 out_unlock0:
1100         ipc_unlock_object(&shp->shm_perm);
1101 out_unlock1:
1102         rcu_read_unlock();
1103         return err;
1104 }
1105
1106 /*
1107  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1108  *
1109  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1110  * "raddr" thing points to kernel space, and there has to be a wrapper around
1111  * this.
1112  */
1113 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1114               ulong *raddr, unsigned long shmlba)
1115 {
1116         struct shmid_kernel *shp;
1117         unsigned long addr = (unsigned long)shmaddr;
1118         unsigned long size;
1119         struct file *file;
1120         int    err;
1121         unsigned long flags = MAP_SHARED;
1122         unsigned long prot;
1123         int acc_mode;
1124         struct ipc_namespace *ns;
1125         struct shm_file_data *sfd;
1126         struct path path;
1127         fmode_t f_mode;
1128         unsigned long populate = 0;
1129
1130         err = -EINVAL;
1131         if (shmid < 0)
1132                 goto out;
1133
1134         if (addr) {
1135                 if (addr & (shmlba - 1)) {
1136                         /*
1137                          * Round down to the nearest multiple of shmlba.
1138                          * For sane do_mmap_pgoff() parameters, avoid
1139                          * round downs that trigger nil-page and MAP_FIXED.
1140                          */
1141                         if ((shmflg & SHM_RND) && addr >= shmlba)
1142                                 addr &= ~(shmlba - 1);
1143                         else
1144 #ifndef __ARCH_FORCE_SHMLBA
1145                                 if (addr & ~PAGE_MASK)
1146 #endif
1147                                         goto out;
1148                 }
1149
1150                 flags |= MAP_FIXED;
1151         } else if ((shmflg & SHM_REMAP))
1152                 goto out;
1153
1154         if (shmflg & SHM_RDONLY) {
1155                 prot = PROT_READ;
1156                 acc_mode = S_IRUGO;
1157                 f_mode = FMODE_READ;
1158         } else {
1159                 prot = PROT_READ | PROT_WRITE;
1160                 acc_mode = S_IRUGO | S_IWUGO;
1161                 f_mode = FMODE_READ | FMODE_WRITE;
1162         }
1163         if (shmflg & SHM_EXEC) {
1164                 prot |= PROT_EXEC;
1165                 acc_mode |= S_IXUGO;
1166         }
1167
1168         /*
1169          * We cannot rely on the fs check since SYSV IPC does have an
1170          * additional creator id...
1171          */
1172         ns = current->nsproxy->ipc_ns;
1173         rcu_read_lock();
1174         shp = shm_obtain_object_check(ns, shmid);
1175         if (IS_ERR(shp)) {
1176                 err = PTR_ERR(shp);
1177                 goto out_unlock;
1178         }
1179
1180         err = -EACCES;
1181         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1182                 goto out_unlock;
1183
1184         err = security_shm_shmat(shp, shmaddr, shmflg);
1185         if (err)
1186                 goto out_unlock;
1187
1188         ipc_lock_object(&shp->shm_perm);
1189
1190         /* check if shm_destroy() is tearing down shp */
1191         if (!ipc_valid_object(&shp->shm_perm)) {
1192                 ipc_unlock_object(&shp->shm_perm);
1193                 err = -EIDRM;
1194                 goto out_unlock;
1195         }
1196
1197         path = shp->shm_file->f_path;
1198         path_get(&path);
1199         shp->shm_nattch++;
1200         size = i_size_read(d_inode(path.dentry));
1201         ipc_unlock_object(&shp->shm_perm);
1202         rcu_read_unlock();
1203
1204         err = -ENOMEM;
1205         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1206         if (!sfd) {
1207                 path_put(&path);
1208                 goto out_nattch;
1209         }
1210
1211         file = alloc_file(&path, f_mode,
1212                           is_file_hugepages(shp->shm_file) ?
1213                                 &shm_file_operations_huge :
1214                                 &shm_file_operations);
1215         err = PTR_ERR(file);
1216         if (IS_ERR(file)) {
1217                 kfree(sfd);
1218                 path_put(&path);
1219                 goto out_nattch;
1220         }
1221
1222         file->private_data = sfd;
1223         file->f_mapping = shp->shm_file->f_mapping;
1224         sfd->id = shp->shm_perm.id;
1225         sfd->ns = get_ipc_ns(ns);
1226         sfd->file = shp->shm_file;
1227         sfd->vm_ops = NULL;
1228
1229         err = security_mmap_file(file, prot, flags);
1230         if (err)
1231                 goto out_fput;
1232
1233         if (down_write_killable(&current->mm->mmap_sem)) {
1234                 err = -EINTR;
1235                 goto out_fput;
1236         }
1237
1238         if (addr && !(shmflg & SHM_REMAP)) {
1239                 err = -EINVAL;
1240                 if (addr + size < addr)
1241                         goto invalid;
1242
1243                 if (find_vma_intersection(current->mm, addr, addr + size))
1244                         goto invalid;
1245         }
1246
1247         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
1248         *raddr = addr;
1249         err = 0;
1250         if (IS_ERR_VALUE(addr))
1251                 err = (long)addr;
1252 invalid:
1253         up_write(&current->mm->mmap_sem);
1254         if (populate)
1255                 mm_populate(addr, populate);
1256
1257 out_fput:
1258         fput(file);
1259
1260 out_nattch:
1261         down_write(&shm_ids(ns).rwsem);
1262         shp = shm_lock(ns, shmid);
1263         shp->shm_nattch--;
1264         if (shm_may_destroy(ns, shp))
1265                 shm_destroy(ns, shp);
1266         else
1267                 shm_unlock(shp);
1268         up_write(&shm_ids(ns).rwsem);
1269         return err;
1270
1271 out_unlock:
1272         rcu_read_unlock();
1273 out:
1274         return err;
1275 }
1276
1277 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1278 {
1279         unsigned long ret;
1280         long err;
1281
1282         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1283         if (err)
1284                 return err;
1285         force_successful_syscall_return();
1286         return (long)ret;
1287 }
1288
1289 /*
1290  * detach and kill segment if marked destroyed.
1291  * The work is done in shm_close.
1292  */
1293 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1294 {
1295         struct mm_struct *mm = current->mm;
1296         struct vm_area_struct *vma;
1297         unsigned long addr = (unsigned long)shmaddr;
1298         int retval = -EINVAL;
1299 #ifdef CONFIG_MMU
1300         loff_t size = 0;
1301         struct file *file;
1302         struct vm_area_struct *next;
1303 #endif
1304
1305         if (addr & ~PAGE_MASK)
1306                 return retval;
1307
1308         if (down_write_killable(&mm->mmap_sem))
1309                 return -EINTR;
1310
1311         /*
1312          * This function tries to be smart and unmap shm segments that
1313          * were modified by partial mlock or munmap calls:
1314          * - It first determines the size of the shm segment that should be
1315          *   unmapped: It searches for a vma that is backed by shm and that
1316          *   started at address shmaddr. It records it's size and then unmaps
1317          *   it.
1318          * - Then it unmaps all shm vmas that started at shmaddr and that
1319          *   are within the initially determined size and that are from the
1320          *   same shm segment from which we determined the size.
1321          * Errors from do_munmap are ignored: the function only fails if
1322          * it's called with invalid parameters or if it's called to unmap
1323          * a part of a vma. Both calls in this function are for full vmas,
1324          * the parameters are directly copied from the vma itself and always
1325          * valid - therefore do_munmap cannot fail. (famous last words?)
1326          */
1327         /*
1328          * If it had been mremap()'d, the starting address would not
1329          * match the usual checks anyway. So assume all vma's are
1330          * above the starting address given.
1331          */
1332         vma = find_vma(mm, addr);
1333
1334 #ifdef CONFIG_MMU
1335         while (vma) {
1336                 next = vma->vm_next;
1337
1338                 /*
1339                  * Check if the starting address would match, i.e. it's
1340                  * a fragment created by mprotect() and/or munmap(), or it
1341                  * otherwise it starts at this address with no hassles.
1342                  */
1343                 if ((vma->vm_ops == &shm_vm_ops) &&
1344                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1345
1346                         /*
1347                          * Record the file of the shm segment being
1348                          * unmapped.  With mremap(), someone could place
1349                          * page from another segment but with equal offsets
1350                          * in the range we are unmapping.
1351                          */
1352                         file = vma->vm_file;
1353                         size = i_size_read(file_inode(vma->vm_file));
1354                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1355                         /*
1356                          * We discovered the size of the shm segment, so
1357                          * break out of here and fall through to the next
1358                          * loop that uses the size information to stop
1359                          * searching for matching vma's.
1360                          */
1361                         retval = 0;
1362                         vma = next;
1363                         break;
1364                 }
1365                 vma = next;
1366         }
1367
1368         /*
1369          * We need look no further than the maximum address a fragment
1370          * could possibly have landed at. Also cast things to loff_t to
1371          * prevent overflows and make comparisons vs. equal-width types.
1372          */
1373         size = PAGE_ALIGN(size);
1374         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1375                 next = vma->vm_next;
1376
1377                 /* finding a matching vma now does not alter retval */
1378                 if ((vma->vm_ops == &shm_vm_ops) &&
1379                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1380                     (vma->vm_file == file))
1381                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1382                 vma = next;
1383         }
1384
1385 #else   /* CONFIG_MMU */
1386         /* under NOMMU conditions, the exact address to be destroyed must be
1387          * given
1388          */
1389         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1390                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1391                 retval = 0;
1392         }
1393
1394 #endif
1395
1396         up_write(&mm->mmap_sem);
1397         return retval;
1398 }
1399
1400 #ifdef CONFIG_PROC_FS
1401 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1402 {
1403         struct user_namespace *user_ns = seq_user_ns(s);
1404         struct shmid_kernel *shp = it;
1405         unsigned long rss = 0, swp = 0;
1406
1407         shm_add_rss_swap(shp, &rss, &swp);
1408
1409 #if BITS_PER_LONG <= 32
1410 #define SIZE_SPEC "%10lu"
1411 #else
1412 #define SIZE_SPEC "%21lu"
1413 #endif
1414
1415         seq_printf(s,
1416                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1417                    "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1418                    SIZE_SPEC " " SIZE_SPEC "\n",
1419                    shp->shm_perm.key,
1420                    shp->shm_perm.id,
1421                    shp->shm_perm.mode,
1422                    shp->shm_segsz,
1423                    shp->shm_cprid,
1424                    shp->shm_lprid,
1425                    shp->shm_nattch,
1426                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1427                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1428                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1429                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1430                    shp->shm_atim,
1431                    shp->shm_dtim,
1432                    shp->shm_ctim,
1433                    rss * PAGE_SIZE,
1434                    swp * PAGE_SIZE);
1435
1436         return 0;
1437 }
1438 #endif