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         if (shp->shm_file != sfd->file) {
 202                 /* ID was reused */
 203                 shm_unlock(shp);
 204                 return -EINVAL;
 205         }
 206
 207         shp->shm_atim = get_seconds();
 208         shp->shm_lprid = task_tgid_vnr(current);
 209         shp->shm_nattch++;
 210         shm_unlock(shp);
 211         return 0;
 212 }
 213
 214 /* This is called by fork, once for every shm attach. */
 215 static void shm_open(struct vm_area_struct *vma)
 216 {
 217         int err = __shm_open(vma);
 218         /*
 219          * We raced in the idr lookup or with shm_destroy().
 220          * Either way, the ID is busted.
 221          */
 222         WARN_ON_ONCE(err);
 223 }
 224
 225 /*
 226  * shm_destroy - free the struct shmid_kernel
 227  *
 228  * @ns: namespace
 229  * @shp: struct to free
 230  *
 231  * It has to be called with shp and shm_ids.rwsem (writer) locked,
 232  * but returns with shp unlocked and freed.
 233  */
 234 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 235 {
 236         struct file *shm_file;
 237
 238         shm_file = shp->shm_file;
 239         shp->shm_file = NULL;
 240         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 241         shm_rmid(ns, shp);
 242         shm_unlock(shp);
 243         if (!is_file_hugepages(shm_file))
 244                 shmem_lock(shm_file, 0, shp->mlock_user);
 245         else if (shp->mlock_user)
 246                 user_shm_unlock(i_size_read(file_inode(shm_file)),
 247                                 shp->mlock_user);
 248         fput(shm_file);
 249         ipc_rcu_putref(shp, shm_rcu_free);
 250 }
 251
 252 /*
 253  * shm_may_destroy - identifies whether shm segment should be destroyed now
 254  *
 255  * Returns true if and only if there are no active users of the segment and
 256  * one of the following is true:
 257  *
 258  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 259  *
 260  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 261  */
 262 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 263 {
 264         return (shp->shm_nattch == 0) &&
 265                (ns->shm_rmid_forced ||
 266                 (shp->shm_perm.mode & SHM_DEST));
 267 }
 268
 269 /*
 270  * remove the attach descriptor vma.
 271  * free memory for segment if it is marked destroyed.
 272  * The descriptor has already been removed from the current->mm->mmap list
 273  * and will later be kfree()d.
 274  */
 275 static void shm_close(struct vm_area_struct *vma)
 276 {
 277         struct file *file = vma->vm_file;
 278         struct shm_file_data *sfd = shm_file_data(file);
 279         struct shmid_kernel *shp;
 280         struct ipc_namespace *ns = sfd->ns;
 281
 282         down_write(&shm_ids(ns).rwsem);
 283         /* remove from the list of attaches of the shm segment */
 284         shp = shm_lock(ns, sfd->id);
 285
 286         /*
 287          * We raced in the idr lookup or with shm_destroy().
 288          * Either way, the ID is busted.
 289          */
 290         if (WARN_ON_ONCE(IS_ERR(shp)))
 291                 goto done; /* no-op */
 292
 293         shp->shm_lprid = task_tgid_vnr(current);
 294         shp->shm_dtim = get_seconds();
 295         shp->shm_nattch--;
 296         if (shm_may_destroy(ns, shp))
 297                 shm_destroy(ns, shp);
 298         else
 299                 shm_unlock(shp);
 300 done:
 301         up_write(&shm_ids(ns).rwsem);
 302 }
 303
 304 /* Called with ns->shm_ids(ns).rwsem locked */
 305 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 306 {
 307         struct ipc_namespace *ns = data;
 308         struct kern_ipc_perm *ipcp = p;
 309         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 310
 311         /*
 312          * We want to destroy segments without users and with already
 313          * exit'ed originating process.
 314          *
 315          * As shp->* are changed under rwsem, it's safe to skip shp locking.
 316          */
 317         if (shp->shm_creator != NULL)
 318                 return 0;
 319
 320         if (shm_may_destroy(ns, shp)) {
 321                 shm_lock_by_ptr(shp);
 322                 shm_destroy(ns, shp);
 323         }
 324         return 0;
 325 }
 326
 327 void shm_destroy_orphaned(struct ipc_namespace *ns)
 328 {
 329         down_write(&shm_ids(ns).rwsem);
 330         if (shm_ids(ns).in_use)
 331                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 332         up_write(&shm_ids(ns).rwsem);
 333 }
 334
 335 /* Locking assumes this will only be called with task == current */
 336 void exit_shm(struct task_struct *task)
 337 {
 338         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 339         struct shmid_kernel *shp, *n;
 340
 341         if (list_empty(&task->sysvshm.shm_clist))
 342                 return;
 343
 344         /*
 345          * If kernel.shm_rmid_forced is not set then only keep track of
 346          * which shmids are orphaned, so that a later set of the sysctl
 347          * can clean them up.
 348          */
 349         if (!ns->shm_rmid_forced) {
 350                 down_read(&shm_ids(ns).rwsem);
 351                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
 352                         shp->shm_creator = NULL;
 353                 /*
 354                  * Only under read lock but we are only called on current
 355                  * so no entry on the list will be shared.
 356                  */
 357                 list_del(&task->sysvshm.shm_clist);
 358                 up_read(&shm_ids(ns).rwsem);
 359                 return;
 360         }
 361
 362         /*
 363          * Destroy all already created segments, that were not yet mapped,
 364          * and mark any mapped as orphan to cover the sysctl toggling.
 365          * Destroy is skipped if shm_may_destroy() returns false.
 366          */
 367         down_write(&shm_ids(ns).rwsem);
 368         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
 369                 shp->shm_creator = NULL;
 370
 371                 if (shm_may_destroy(ns, shp)) {
 372                         shm_lock_by_ptr(shp);
 373                         shm_destroy(ns, shp);
 374                 }
 375         }
 376
 377         /* Remove the list head from any segments still attached. */
 378         list_del(&task->sysvshm.shm_clist);
 379         up_write(&shm_ids(ns).rwsem);
 380 }
 381
 382 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 383 {
 384         struct file *file = vma->vm_file;
 385         struct shm_file_data *sfd = shm_file_data(file);
 386
 387         return sfd->vm_ops->fault(vma, vmf);
 388 }
 389
 390 static int shm_split(struct vm_area_struct *vma, unsigned long addr)
 391 {
 392         struct file *file = vma->vm_file;
 393         struct shm_file_data *sfd = shm_file_data(file);
 394
 395         if (sfd->vm_ops && sfd->vm_ops->split)
 396                 return sfd->vm_ops->split(vma, addr);
 397
 398         return 0;
 399 }
 400
 401 #ifdef CONFIG_NUMA
 402 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 403 {
 404         struct file *file = vma->vm_file;
 405         struct shm_file_data *sfd = shm_file_data(file);
 406         int err = 0;
 407         if (sfd->vm_ops->set_policy)
 408                 err = sfd->vm_ops->set_policy(vma, new);
 409         return err;
 410 }
 411
 412 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 413                                         unsigned long addr)
 414 {
 415         struct file *file = vma->vm_file;
 416         struct shm_file_data *sfd = shm_file_data(file);
 417         struct mempolicy *pol = NULL;
 418
 419         if (sfd->vm_ops->get_policy)
 420                 pol = sfd->vm_ops->get_policy(vma, addr);
 421         else if (vma->vm_policy)
 422                 pol = vma->vm_policy;
 423
 424         return pol;
 425 }
 426 #endif
 427
 428 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 429 {
 430         struct shm_file_data *sfd = shm_file_data(file);
 431         int ret;
 432
 433         /*
 434          * In case of remap_file_pages() emulation, the file can represent an
 435          * IPC ID that was removed, and possibly even reused by another shm
 436          * segment already.  Propagate this case as an error to caller.
 437          */
 438         ret =__shm_open(vma);
 439         if (ret)
 440                 return ret;
 441
 442         ret = sfd->file->f_op->mmap(sfd->file, vma);
 443         if (ret) {
 444                 shm_close(vma);
 445                 return ret;
 446         }
 447         sfd->vm_ops = vma->vm_ops;
 448 #ifdef CONFIG_MMU
 449         WARN_ON(!sfd->vm_ops->fault);
 450 #endif
 451         vma->vm_ops = &shm_vm_ops;
 452         return 0;
 453 }
 454
 455 static int shm_release(struct inode *ino, struct file *file)
 456 {
 457         struct shm_file_data *sfd = shm_file_data(file);
 458
 459         put_ipc_ns(sfd->ns);
 460         fput(sfd->file);
 461         shm_file_data(file) = NULL;
 462         kfree(sfd);
 463         return 0;
 464 }
 465
 466 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 467 {
 468         struct shm_file_data *sfd = shm_file_data(file);
 469
 470         if (!sfd->file->f_op->fsync)
 471                 return -EINVAL;
 472         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 473 }
 474
 475 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 476                           loff_t len)
 477 {
 478         struct shm_file_data *sfd = shm_file_data(file);
 479
 480         if (!sfd->file->f_op->fallocate)
 481                 return -EOPNOTSUPP;
 482         return sfd->file->f_op->fallocate(file, mode, offset, len);
 483 }
 484
 485 static unsigned long shm_get_unmapped_area(struct file *file,
 486         unsigned long addr, unsigned long len, unsigned long pgoff,
 487         unsigned long flags)
 488 {
 489         struct shm_file_data *sfd = shm_file_data(file);
 490         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 491                                                 pgoff, flags);
 492 }
 493
 494 static const struct file_operations shm_file_operations = {
 495         .mmap           = shm_mmap,
 496         .fsync          = shm_fsync,
 497         .release        = shm_release,
 498         .get_unmapped_area      = shm_get_unmapped_area,
 499         .llseek         = noop_llseek,
 500         .fallocate      = shm_fallocate,
 501 };
 502
 503 /*
 504  * shm_file_operations_huge is now identical to shm_file_operations,
 505  * but we keep it distinct for the sake of is_file_shm_hugepages().
 506  */
 507 static const struct file_operations shm_file_operations_huge = {
 508         .mmap           = shm_mmap,
 509         .fsync          = shm_fsync,
 510         .release        = shm_release,
 511         .get_unmapped_area      = shm_get_unmapped_area,
 512         .llseek         = noop_llseek,
 513         .fallocate      = shm_fallocate,
 514 };
 515
 516 bool is_file_shm_hugepages(struct file *file)
 517 {
 518         return file->f_op == &shm_file_operations_huge;
 519 }
 520
 521 static const struct vm_operations_struct shm_vm_ops = {
 522         .open   = shm_open,     /* callback for a new vm-area open */
 523         .close  = shm_close,    /* callback for when the vm-area is released */
 524         .fault  = shm_fault,
 525         .split  = shm_split,
 526 #if defined(CONFIG_NUMA)
 527         .set_policy = shm_set_policy,
 528         .get_policy = shm_get_policy,
 529 #endif
 530 };
 531
 532 /**
 533  * newseg - Create a new shared memory segment
 534  * @ns: namespace
 535  * @params: ptr to the structure that contains key, size and shmflg
 536  *
 537  * Called with shm_ids.rwsem held as a writer.
 538  */
 539 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 540 {
 541         key_t key = params->key;
 542         int shmflg = params->flg;
 543         size_t size = params->u.size;
 544         int error;
 545         struct shmid_kernel *shp;
 546         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 547         struct file *file;
 548         char name[13];
 549         int id;
 550         vm_flags_t acctflag = 0;
 551
 552         if (size < SHMMIN || size > ns->shm_ctlmax)
 553                 return -EINVAL;
 554
 555         if (numpages << PAGE_SHIFT < size)
 556                 return -ENOSPC;
 557
 558         if (ns->shm_tot + numpages < ns->shm_tot ||
 559                         ns->shm_tot + numpages > ns->shm_ctlall)
 560                 return -ENOSPC;
 561
 562         shp = ipc_rcu_alloc(sizeof(*shp));
 563         if (!shp)
 564                 return -ENOMEM;
 565
 566         shp->shm_perm.key = key;
 567         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 568         shp->mlock_user = NULL;
 569
 570         shp->shm_perm.security = NULL;
 571         error = security_shm_alloc(shp);
 572         if (error) {
 573                 ipc_rcu_putref(shp, ipc_rcu_free);
 574                 return error;
 575         }
 576
 577         sprintf(name, "SYSV%08x", key);
 578         if (shmflg & SHM_HUGETLB) {
 579                 struct hstate *hs;
 580                 size_t hugesize;
 581
 582                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 583                 if (!hs) {
 584                         error = -EINVAL;
 585                         goto no_file;
 586                 }
 587                 hugesize = ALIGN(size, huge_page_size(hs));
 588
 589                 /* hugetlb_file_setup applies strict accounting */
 590                 if (shmflg & SHM_NORESERVE)
 591                         acctflag = VM_NORESERVE;
 592                 file = hugetlb_file_setup(name, hugesize, acctflag,
 593                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
 594                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 595         } else {
 596                 /*
 597                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 598                  * if it's asked for.
 599                  */
 600                 if  ((shmflg & SHM_NORESERVE) &&
 601                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 602                         acctflag = VM_NORESERVE;
 603                 file = shmem_kernel_file_setup(name, size, acctflag);
 604         }
 605         error = PTR_ERR(file);
 606         if (IS_ERR(file))
 607                 goto no_file;
 608
 609         shp->shm_cprid = task_tgid_vnr(current);
 610         shp->shm_lprid = 0;
 611         shp->shm_atim = shp->shm_dtim = 0;
 612         shp->shm_ctim = get_seconds();
 613         shp->shm_segsz = size;
 614         shp->shm_nattch = 0;
 615         shp->shm_file = file;
 616         shp->shm_creator = current;
 617
 618         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 619         if (id < 0) {
 620                 error = id;
 621                 goto no_id;
 622         }
 623
 624         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 625
 626         /*
 627          * shmid gets reported as "inode#" in /proc/pid/maps.
 628          * proc-ps tools use this. Changing this will break them.
 629          */
 630         file_inode(file)->i_ino = shp->shm_perm.id;
 631
 632         ns->shm_tot += numpages;
 633         error = shp->shm_perm.id;
 634
 635         ipc_unlock_object(&shp->shm_perm);
 636         rcu_read_unlock();
 637         return error;
 638
 639 no_id:
 640         if (is_file_hugepages(file) && shp->mlock_user)
 641                 user_shm_unlock(size, shp->mlock_user);
 642         fput(file);
 643 no_file:
 644         ipc_rcu_putref(shp, shm_rcu_free);
 645         return error;
 646 }
 647
 648 /*
 649  * Called with shm_ids.rwsem and ipcp locked.
 650  */
 651 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 652 {
 653         struct shmid_kernel *shp;
 654
 655         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 656         return security_shm_associate(shp, shmflg);
 657 }
 658
 659 /*
 660  * Called with shm_ids.rwsem and ipcp locked.
 661  */
 662 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 663                                 struct ipc_params *params)
 664 {
 665         struct shmid_kernel *shp;
 666
 667         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 668         if (shp->shm_segsz < params->u.size)
 669                 return -EINVAL;
 670
 671         return 0;
 672 }
 673
 674 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 675 {
 676         struct ipc_namespace *ns;
 677         static const struct ipc_ops shm_ops = {
 678                 .getnew = newseg,
 679                 .associate = shm_security,
 680                 .more_checks = shm_more_checks,
 681         };
 682         struct ipc_params shm_params;
 683
 684         ns = current->nsproxy->ipc_ns;
 685
 686         shm_params.key = key;
 687         shm_params.flg = shmflg;
 688         shm_params.u.size = size;
 689
 690         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 691 }
 692
 693 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 694 {
 695         switch (version) {
 696         case IPC_64:
 697                 return copy_to_user(buf, in, sizeof(*in));
 698         case IPC_OLD:
 699             {
 700                 struct shmid_ds out;
 701
 702                 memset(&out, 0, sizeof(out));
 703                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 704                 out.shm_segsz   = in->shm_segsz;
 705                 out.shm_atime   = in->shm_atime;
 706                 out.shm_dtime   = in->shm_dtime;
 707                 out.shm_ctime   = in->shm_ctime;
 708                 out.shm_cpid    = in->shm_cpid;
 709                 out.shm_lpid    = in->shm_lpid;
 710                 out.shm_nattch  = in->shm_nattch;
 711
 712                 return copy_to_user(buf, &out, sizeof(out));
 713             }
 714         default:
 715                 return -EINVAL;
 716         }
 717 }
 718
 719 static inline unsigned long
 720 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 721 {
 722         switch (version) {
 723         case IPC_64:
 724                 if (copy_from_user(out, buf, sizeof(*out)))
 725                         return -EFAULT;
 726                 return 0;
 727         case IPC_OLD:
 728             {
 729                 struct shmid_ds tbuf_old;
 730
 731                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 732                         return -EFAULT;
 733
 734                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 735                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 736                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 737
 738                 return 0;
 739             }
 740         default:
 741                 return -EINVAL;
 742         }
 743 }
 744
 745 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 746 {
 747         switch (version) {
 748         case IPC_64:
 749                 return copy_to_user(buf, in, sizeof(*in));
 750         case IPC_OLD:
 751             {
 752                 struct shminfo out;
 753
 754                 if (in->shmmax > INT_MAX)
 755                         out.shmmax = INT_MAX;
 756                 else
 757                         out.shmmax = (int)in->shmmax;
 758
 759                 out.shmmin      = in->shmmin;
 760                 out.shmmni      = in->shmmni;
 761                 out.shmseg      = in->shmseg;
 762                 out.shmall      = in->shmall;
 763
 764                 return copy_to_user(buf, &out, sizeof(out));
 765             }
 766         default:
 767                 return -EINVAL;
 768         }
 769 }
 770
 771 /*
 772  * Calculate and add used RSS and swap pages of a shm.
 773  * Called with shm_ids.rwsem held as a reader
 774  */
 775 static void shm_add_rss_swap(struct shmid_kernel *shp,
 776         unsigned long *rss_add, unsigned long *swp_add)
 777 {
 778         struct inode *inode;
 779
 780         inode = file_inode(shp->shm_file);
 781
 782         if (is_file_hugepages(shp->shm_file)) {
 783                 struct address_space *mapping = inode->i_mapping;
 784                 struct hstate *h = hstate_file(shp->shm_file);
 785                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 786         } else {
 787 #ifdef CONFIG_SHMEM
 788                 struct shmem_inode_info *info = SHMEM_I(inode);
 789                 spin_lock_irq(&info->lock);
 790                 *rss_add += inode->i_mapping->nrpages;
 791                 *swp_add += info->swapped;
 792                 spin_unlock_irq(&info->lock);
 793 #else
 794                 *rss_add += inode->i_mapping->nrpages;
 795 #endif
 796         }
 797 }
 798
 799 /*
 800  * Called with shm_ids.rwsem held as a reader
 801  */
 802 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 803                 unsigned long *swp)
 804 {
 805         int next_id;
 806         int total, in_use;
 807
 808         *rss = 0;
 809         *swp = 0;
 810
 811         in_use = shm_ids(ns).in_use;
 812
 813         for (total = 0, next_id = 0; total < in_use; next_id++) {
 814                 struct kern_ipc_perm *ipc;
 815                 struct shmid_kernel *shp;
 816
 817                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 818                 if (ipc == NULL)
 819                         continue;
 820                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 821
 822                 shm_add_rss_swap(shp, rss, swp);
 823
 824                 total++;
 825         }
 826 }
 827
 828 /*
 829  * This function handles some shmctl commands which require the rwsem
 830  * to be held in write mode.
 831  * NOTE: no locks must be held, the rwsem is taken inside this function.
 832  */
 833 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 834                        struct shmid_ds __user *buf, int version)
 835 {
 836         struct kern_ipc_perm *ipcp;
 837         struct shmid64_ds shmid64;
 838         struct shmid_kernel *shp;
 839         int err;
 840
 841         if (cmd == IPC_SET) {
 842                 if (copy_shmid_from_user(&shmid64, buf, version))
 843                         return -EFAULT;
 844         }
 845
 846         down_write(&shm_ids(ns).rwsem);
 847         rcu_read_lock();
 848
 849         ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
 850                                       &shmid64.shm_perm, 0);
 851         if (IS_ERR(ipcp)) {
 852                 err = PTR_ERR(ipcp);
 853                 goto out_unlock1;
 854         }
 855
 856         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 857
 858         err = security_shm_shmctl(shp, cmd);
 859         if (err)
 860                 goto out_unlock1;
 861
 862         switch (cmd) {
 863         case IPC_RMID:
 864                 ipc_lock_object(&shp->shm_perm);
 865                 /* do_shm_rmid unlocks the ipc object and rcu */
 866                 do_shm_rmid(ns, ipcp);
 867                 goto out_up;
 868         case IPC_SET:
 869                 ipc_lock_object(&shp->shm_perm);
 870                 err = ipc_update_perm(&shmid64.shm_perm, ipcp);
 871                 if (err)
 872                         goto out_unlock0;
 873                 shp->shm_ctim = get_seconds();
 874                 break;
 875         default:
 876                 err = -EINVAL;
 877                 goto out_unlock1;
 878         }
 879
 880 out_unlock0:
 881         ipc_unlock_object(&shp->shm_perm);
 882 out_unlock1:
 883         rcu_read_unlock();
 884 out_up:
 885         up_write(&shm_ids(ns).rwsem);
 886         return err;
 887 }
 888
 889 static int shmctl_nolock(struct ipc_namespace *ns, int shmid,
 890                          int cmd, int version, void __user *buf)
 891 {
 892         int err;
 893         struct shmid_kernel *shp;
 894
 895         /* preliminary security checks for *_INFO */
 896         if (cmd == IPC_INFO || cmd == SHM_INFO) {
 897                 err = security_shm_shmctl(NULL, cmd);
 898                 if (err)
 899                         return err;
 900         }
 901
 902         switch (cmd) {
 903         case IPC_INFO:
 904         {
 905                 struct shminfo64 shminfo;
 906
 907                 memset(&shminfo, 0, sizeof(shminfo));
 908                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 909                 shminfo.shmmax = ns->shm_ctlmax;
 910                 shminfo.shmall = ns->shm_ctlall;
 911
 912                 shminfo.shmmin = SHMMIN;
 913                 if (copy_shminfo_to_user(buf, &shminfo, version))
 914                         return -EFAULT;
 915
 916                 down_read(&shm_ids(ns).rwsem);
 917                 err = ipc_get_maxid(&shm_ids(ns));
 918                 up_read(&shm_ids(ns).rwsem);
 919
 920                 if (err < 0)
 921                         err = 0;
 922                 goto out;
 923         }
 924         case SHM_INFO:
 925         {
 926                 struct shm_info shm_info;
 927
 928                 memset(&shm_info, 0, sizeof(shm_info));
 929                 down_read(&shm_ids(ns).rwsem);
 930                 shm_info.used_ids = shm_ids(ns).in_use;
 931                 shm_get_stat(ns, &shm_info.shm_rss, &shm_info.shm_swp);
 932                 shm_info.shm_tot = ns->shm_tot;
 933                 shm_info.swap_attempts = 0;
 934                 shm_info.swap_successes = 0;
 935                 err = ipc_get_maxid(&shm_ids(ns));
 936                 up_read(&shm_ids(ns).rwsem);
 937                 if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 938                         err = -EFAULT;
 939                         goto out;
 940                 }
 941
 942                 err = err < 0 ? 0 : err;
 943                 goto out;
 944         }
 945         case SHM_STAT:
 946         case IPC_STAT:
 947         {
 948                 struct shmid64_ds tbuf;
 949                 int result;
 950
 951                 rcu_read_lock();
 952                 if (cmd == SHM_STAT) {
 953                         shp = shm_obtain_object(ns, shmid);
 954                         if (IS_ERR(shp)) {
 955                                 err = PTR_ERR(shp);
 956                                 goto out_unlock;
 957                         }
 958                         result = shp->shm_perm.id;
 959                 } else {
 960                         shp = shm_obtain_object_check(ns, shmid);
 961                         if (IS_ERR(shp)) {
 962                                 err = PTR_ERR(shp);
 963                                 goto out_unlock;
 964                         }
 965                         result = 0;
 966                 }
 967
 968                 err = -EACCES;
 969                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 970                         goto out_unlock;
 971
 972                 err = security_shm_shmctl(shp, cmd);
 973                 if (err)
 974                         goto out_unlock;
 975
 976                 memset(&tbuf, 0, sizeof(tbuf));
 977                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 978                 tbuf.shm_segsz  = shp->shm_segsz;
 979                 tbuf.shm_atime  = shp->shm_atim;
 980                 tbuf.shm_dtime  = shp->shm_dtim;
 981                 tbuf.shm_ctime  = shp->shm_ctim;
 982                 tbuf.shm_cpid   = shp->shm_cprid;
 983                 tbuf.shm_lpid   = shp->shm_lprid;
 984                 tbuf.shm_nattch = shp->shm_nattch;
 985                 rcu_read_unlock();
 986
 987                 if (copy_shmid_to_user(buf, &tbuf, version))
 988                         err = -EFAULT;
 989                 else
 990                         err = result;
 991                 goto out;
 992         }
 993         default:
 994                 return -EINVAL;
 995         }
 996
 997 out_unlock:
 998         rcu_read_unlock();
 999 out:
1000         return err;
1001 }
1002
1003 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1004 {
1005         struct shmid_kernel *shp;
1006         int err, version;
1007         struct ipc_namespace *ns;
1008
1009         if (cmd < 0 || shmid < 0)
1010                 return -EINVAL;
1011
1012         version = ipc_parse_version(&cmd);
1013         ns = current->nsproxy->ipc_ns;
1014
1015         switch (cmd) {
1016         case IPC_INFO:
1017         case SHM_INFO:
1018         case SHM_STAT:
1019         case IPC_STAT:
1020                 return shmctl_nolock(ns, shmid, cmd, version, buf);
1021         case IPC_RMID:
1022         case IPC_SET:
1023                 return shmctl_down(ns, shmid, cmd, buf, version);
1024         case SHM_LOCK:
1025         case SHM_UNLOCK:
1026         {
1027                 struct file *shm_file;
1028
1029                 rcu_read_lock();
1030                 shp = shm_obtain_object_check(ns, shmid);
1031                 if (IS_ERR(shp)) {
1032                         err = PTR_ERR(shp);
1033                         goto out_unlock1;
1034                 }
1035
1036                 audit_ipc_obj(&(shp->shm_perm));
1037                 err = security_shm_shmctl(shp, cmd);
1038                 if (err)
1039                         goto out_unlock1;
1040
1041                 ipc_lock_object(&shp->shm_perm);
1042
1043                 /* check if shm_destroy() is tearing down shp */
1044                 if (!ipc_valid_object(&shp->shm_perm)) {
1045                         err = -EIDRM;
1046                         goto out_unlock0;
1047                 }
1048
1049                 if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1050                         kuid_t euid = current_euid();
1051                         if (!uid_eq(euid, shp->shm_perm.uid) &&
1052                             !uid_eq(euid, shp->shm_perm.cuid)) {
1053                                 err = -EPERM;
1054                                 goto out_unlock0;
1055                         }
1056                         if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1057                                 err = -EPERM;
1058                                 goto out_unlock0;
1059                         }
1060                 }
1061
1062                 shm_file = shp->shm_file;
1063                 if (is_file_hugepages(shm_file))
1064                         goto out_unlock0;
1065
1066                 if (cmd == SHM_LOCK) {
1067                         struct user_struct *user = current_user();
1068                         err = shmem_lock(shm_file, 1, user);
1069                         if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1070                                 shp->shm_perm.mode |= SHM_LOCKED;
1071                                 shp->mlock_user = user;
1072                         }
1073                         goto out_unlock0;
1074                 }
1075
1076                 /* SHM_UNLOCK */
1077                 if (!(shp->shm_perm.mode & SHM_LOCKED))
1078                         goto out_unlock0;
1079                 shmem_lock(shm_file, 0, shp->mlock_user);
1080                 shp->shm_perm.mode &= ~SHM_LOCKED;
1081                 shp->mlock_user = NULL;
1082                 get_file(shm_file);
1083                 ipc_unlock_object(&shp->shm_perm);
1084                 rcu_read_unlock();
1085                 shmem_unlock_mapping(shm_file->f_mapping);
1086
1087                 fput(shm_file);
1088                 return err;
1089         }
1090         default:
1091                 return -EINVAL;
1092         }
1093
1094 out_unlock0:
1095         ipc_unlock_object(&shp->shm_perm);
1096 out_unlock1:
1097         rcu_read_unlock();
1098         return err;
1099 }
1100
1101 /*
1102  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1103  *
1104  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1105  * "raddr" thing points to kernel space, and there has to be a wrapper around
1106  * this.
1107  */
1108 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1109               ulong *raddr, unsigned long shmlba)
1110 {
1111         struct shmid_kernel *shp;
1112         unsigned long addr;
1113         unsigned long size;
1114         struct file *file;
1115         int    err;
1116         unsigned long flags;
1117         unsigned long prot;
1118         int acc_mode;
1119         struct ipc_namespace *ns;
1120         struct shm_file_data *sfd;
1121         struct path path;
1122         fmode_t f_mode;
1123         unsigned long populate = 0;
1124
1125         err = -EINVAL;
1126         if (shmid < 0)
1127                 goto out;
1128         else if ((addr = (ulong)shmaddr)) {
1129                 if (addr & (shmlba - 1)) {
1130                         if (shmflg & SHM_RND) {
1131                                 addr &= ~(shmlba - 1);  /* round down */
1132
1133                                 /*
1134                                  * Ensure that the round-down is non-nil
1135                                  * when remapping. This can happen for
1136                                  * cases when addr < shmlba.
1137                                  */
1138                                 if (!addr && (shmflg & SHM_REMAP))
1139                                         goto out;
1140                         } else
1141 #ifndef __ARCH_FORCE_SHMLBA
1142                                 if (addr & ~PAGE_MASK)
1143 #endif
1144                                         goto out;
1145                 }
1146                 flags = MAP_SHARED | MAP_FIXED;
1147         } else {
1148                 if ((shmflg & SHM_REMAP))
1149                         goto out;
1150
1151                 flags = MAP_SHARED;
1152         }
1153
1154         if (shmflg & SHM_RDONLY) {
1155                 prot = PROT_READ;
1156                 acc_mode = S_IRUGO;
1157                 f_mode = FMODE_READ;
1158         } else {
1159                 prot = PROT_READ | PROT_WRITE;
1160                 acc_mode = S_IRUGO | S_IWUGO;
1161                 f_mode = FMODE_READ | FMODE_WRITE;
1162         }
1163         if (shmflg & SHM_EXEC) {
1164                 prot |= PROT_EXEC;
1165                 acc_mode |= S_IXUGO;
1166         }
1167
1168         /*
1169          * We cannot rely on the fs check since SYSV IPC does have an
1170          * additional creator id...
1171          */
1172         ns = current->nsproxy->ipc_ns;
1173         rcu_read_lock();
1174         shp = shm_obtain_object_check(ns, shmid);
1175         if (IS_ERR(shp)) {
1176                 err = PTR_ERR(shp);
1177                 goto out_unlock;
1178         }
1179
1180         err = -EACCES;
1181         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1182                 goto out_unlock;
1183
1184         err = security_shm_shmat(shp, shmaddr, shmflg);
1185         if (err)
1186                 goto out_unlock;
1187
1188         ipc_lock_object(&shp->shm_perm);
1189
1190         /* check if shm_destroy() is tearing down shp */
1191         if (!ipc_valid_object(&shp->shm_perm)) {
1192                 ipc_unlock_object(&shp->shm_perm);
1193                 err = -EIDRM;
1194                 goto out_unlock;
1195         }
1196
1197         path = shp->shm_file->f_path;
1198         path_get(&path);
1199         shp->shm_nattch++;
1200         size = i_size_read(d_inode(path.dentry));
1201         ipc_unlock_object(&shp->shm_perm);
1202         rcu_read_unlock();
1203
1204         err = -ENOMEM;
1205         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1206         if (!sfd) {
1207                 path_put(&path);
1208                 goto out_nattch;
1209         }
1210
1211         file = alloc_file(&path, f_mode,
1212                           is_file_hugepages(shp->shm_file) ?
1213                                 &shm_file_operations_huge :
1214                                 &shm_file_operations);
1215         err = PTR_ERR(file);
1216         if (IS_ERR(file)) {
1217                 kfree(sfd);
1218                 path_put(&path);
1219                 goto out_nattch;
1220         }
1221
1222         file->private_data = sfd;
1223         file->f_mapping = shp->shm_file->f_mapping;
1224         sfd->id = shp->shm_perm.id;
1225         sfd->ns = get_ipc_ns(ns);
1226         /*
1227          * We need to take a reference to the real shm file to prevent the
1228          * pointer from becoming stale in cases where the lifetime of the outer
1229          * file extends beyond that of the shm segment.  It's not usually
1230          * possible, but it can happen during remap_file_pages() emulation as
1231          * that unmaps the memory, then does ->mmap() via file reference only.
1232          * We'll deny the ->mmap() if the shm segment was since removed, but to
1233          * detect shm ID reuse we need to compare the file pointers.
1234          */
1235         sfd->file = get_file(shp->shm_file);
1236         sfd->vm_ops = NULL;
1237
1238         err = security_mmap_file(file, prot, flags);
1239         if (err)
1240                 goto out_fput;
1241
1242         if (down_write_killable(&current->mm->mmap_sem)) {
1243                 err = -EINTR;
1244                 goto out_fput;
1245         }
1246
1247         if (addr && !(shmflg & SHM_REMAP)) {
1248                 err = -EINVAL;
1249                 if (addr + size < addr)
1250                         goto invalid;
1251
1252                 if (find_vma_intersection(current->mm, addr, addr + size))
1253                         goto invalid;
1254         }
1255
1256         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate);
1257         *raddr = addr;
1258         err = 0;
1259         if (IS_ERR_VALUE(addr))
1260                 err = (long)addr;
1261 invalid:
1262         up_write(&current->mm->mmap_sem);
1263         if (populate)
1264                 mm_populate(addr, populate);
1265
1266 out_fput:
1267         fput(file);
1268
1269 out_nattch:
1270         down_write(&shm_ids(ns).rwsem);
1271         shp = shm_lock(ns, shmid);
1272         shp->shm_nattch--;
1273         if (shm_may_destroy(ns, shp))
1274                 shm_destroy(ns, shp);
1275         else
1276                 shm_unlock(shp);
1277         up_write(&shm_ids(ns).rwsem);
1278         return err;
1279
1280 out_unlock:
1281         rcu_read_unlock();
1282 out:
1283         return err;
1284 }
1285
1286 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1287 {
1288         unsigned long ret;
1289         long err;
1290
1291         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1292         if (err)
1293                 return err;
1294         force_successful_syscall_return();
1295         return (long)ret;
1296 }
1297
1298 /*
1299  * detach and kill segment if marked destroyed.
1300  * The work is done in shm_close.
1301  */
1302 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1303 {
1304         struct mm_struct *mm = current->mm;
1305         struct vm_area_struct *vma;
1306         unsigned long addr = (unsigned long)shmaddr;
1307         int retval = -EINVAL;
1308 #ifdef CONFIG_MMU
1309         loff_t size = 0;
1310         struct file *file;
1311         struct vm_area_struct *next;
1312 #endif
1313
1314         if (addr & ~PAGE_MASK)
1315                 return retval;
1316
1317         if (down_write_killable(&mm->mmap_sem))
1318                 return -EINTR;
1319
1320         /*
1321          * This function tries to be smart and unmap shm segments that
1322          * were modified by partial mlock or munmap calls:
1323          * - It first determines the size of the shm segment that should be
1324          *   unmapped: It searches for a vma that is backed by shm and that
1325          *   started at address shmaddr. It records it's size and then unmaps
1326          *   it.
1327          * - Then it unmaps all shm vmas that started at shmaddr and that
1328          *   are within the initially determined size and that are from the
1329          *   same shm segment from which we determined the size.
1330          * Errors from do_munmap are ignored: the function only fails if
1331          * it's called with invalid parameters or if it's called to unmap
1332          * a part of a vma. Both calls in this function are for full vmas,
1333          * the parameters are directly copied from the vma itself and always
1334          * valid - therefore do_munmap cannot fail. (famous last words?)
1335          */
1336         /*
1337          * If it had been mremap()'d, the starting address would not
1338          * match the usual checks anyway. So assume all vma's are
1339          * above the starting address given.
1340          */
1341         vma = find_vma(mm, addr);
1342
1343 #ifdef CONFIG_MMU
1344         while (vma) {
1345                 next = vma->vm_next;
1346
1347                 /*
1348                  * Check if the starting address would match, i.e. it's
1349                  * a fragment created by mprotect() and/or munmap(), or it
1350                  * otherwise it starts at this address with no hassles.
1351                  */
1352                 if ((vma->vm_ops == &shm_vm_ops) &&
1353                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1354
1355                         /*
1356                          * Record the file of the shm segment being
1357                          * unmapped.  With mremap(), someone could place
1358                          * page from another segment but with equal offsets
1359                          * in the range we are unmapping.
1360                          */
1361                         file = vma->vm_file;
1362                         size = i_size_read(file_inode(vma->vm_file));
1363                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1364                         /*
1365                          * We discovered the size of the shm segment, so
1366                          * break out of here and fall through to the next
1367                          * loop that uses the size information to stop
1368                          * searching for matching vma's.
1369                          */
1370                         retval = 0;
1371                         vma = next;
1372                         break;
1373                 }
1374                 vma = next;
1375         }
1376
1377         /*
1378          * We need look no further than the maximum address a fragment
1379          * could possibly have landed at. Also cast things to loff_t to
1380          * prevent overflows and make comparisons vs. equal-width types.
1381          */
1382         size = PAGE_ALIGN(size);
1383         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1384                 next = vma->vm_next;
1385
1386                 /* finding a matching vma now does not alter retval */
1387                 if ((vma->vm_ops == &shm_vm_ops) &&
1388                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1389                     (vma->vm_file == file))
1390                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1391                 vma = next;
1392         }
1393
1394 #else /* CONFIG_MMU */
1395         /* under NOMMU conditions, the exact address to be destroyed must be
1396          * given */
1397         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1398                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1399                 retval = 0;
1400         }
1401
1402 #endif
1403
1404         up_write(&mm->mmap_sem);
1405         return retval;
1406 }
1407
1408 #ifdef CONFIG_PROC_FS
1409 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1410 {
1411         struct user_namespace *user_ns = seq_user_ns(s);
1412         struct shmid_kernel *shp = it;
1413         unsigned long rss = 0, swp = 0;
1414
1415         shm_add_rss_swap(shp, &rss, &swp);
1416
1417 #if BITS_PER_LONG <= 32
1418 #define SIZE_SPEC "%10lu"
1419 #else
1420 #define SIZE_SPEC "%21lu"
1421 #endif
1422
1423         seq_printf(s,
1424                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1425                    "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1426                    SIZE_SPEC " " SIZE_SPEC "\n",
1427                    shp->shm_perm.key,
1428                    shp->shm_perm.id,
1429                    shp->shm_perm.mode,
1430                    shp->shm_segsz,
1431                    shp->shm_cprid,
1432                    shp->shm_lprid,
1433                    shp->shm_nattch,
1434                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1435                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1436                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1437                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1438                    shp->shm_atim,
1439                    shp->shm_dtim,
1440                    shp->shm_ctim,
1441                    rss * PAGE_SIZE,
1442                    swp * PAGE_SIZE);
1443
1444         return 0;
1445 }
1446 #endif