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