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