ipc/shm.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/ipc/shm.c
   4  * Copyright (C) 1992, 1993 Krishna Balasubramanian
   5  *       Many improvements/fixes by Bruno Haible.
   6  * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
   7  * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
   8  *
   9  * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <[email protected]>
  10  * BIGMEM support, Andrea Arcangeli <[email protected]>
  11  * SMP thread shm, Jean-Luc Boyard <[email protected]>
  12  * HIGHMEM support, Ingo Molnar <[email protected]>
  13  * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <[email protected]>
  14  * Shared /dev/zero support, Kanoj Sarcar <[email protected]>
  15  * Move the mm functionality over to mm/shmem.c, Christoph Rohland <[email protected]>
  16  *
  17  * support for audit of ipc object properties and permission changes
  18  * Dustin Kirkland <[email protected]>
  19  *
  20  * namespaces support
  21  * OpenVZ, SWsoft Inc.
  22  * Pavel Emelianov <[email protected]>
  23  *
  24  * Better ipc lock (kern_ipc_perm.lock) handling
  25  * Davidlohr Bueso <[email protected]>, June 2013.
  26  */
  27
  28 #include <linux/slab.h>
  29 #include <linux/mm.h>
  30 #include <linux/hugetlb.h>
  31 #include <linux/shm.h>
  32 #include <linux/init.h>
  33 #include <linux/file.h>
  34 #include <linux/mman.h>
  35 #include <linux/shmem_fs.h>
  36 #include <linux/security.h>
  37 #include <linux/syscalls.h>
  38 #include <linux/audit.h>
  39 #include <linux/capability.h>
  40 #include <linux/ptrace.h>
  41 #include <linux/seq_file.h>
  42 #include <linux/rwsem.h>
  43 #include <linux/nsproxy.h>
  44 #include <linux/mount.h>
  45 #include <linux/ipc_namespace.h>
  46 #include <linux/rhashtable.h>
  47
  48 #include <linux/uaccess.h>
  49
  50 #include "util.h"
  51
  52 struct shmid_kernel /* private to the kernel */
  53 {
  54         struct kern_ipc_perm    shm_perm;
  55         struct file             *shm_file;
  56         unsigned long           shm_nattch;
  57         unsigned long           shm_segsz;
  58         time64_t                shm_atim;
  59         time64_t                shm_dtim;
  60         time64_t                shm_ctim;
  61         struct pid              *shm_cprid;
  62         struct pid              *shm_lprid;
  63         struct user_struct      *mlock_user;
  64
  65         /* The task created the shm object.  NULL if the task is dead. */
  66         struct task_struct      *shm_creator;
  67         struct list_head        shm_clist;      /* list by creator */
  68 } __randomize_layout;
  69
  70 /* shm_mode upper byte flags */
  71 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  72 #define SHM_LOCKED      02000   /* segment will not be swapped */
  73
  74 struct shm_file_data {
  75         int id;
  76         struct ipc_namespace *ns;
  77         struct file *file;
  78         const struct vm_operations_struct *vm_ops;
  79 };
  80
  81 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  82
  83 static const struct file_operations shm_file_operations;
  84 static const struct vm_operations_struct shm_vm_ops;
  85
  86 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
  87
  88 #define shm_unlock(shp)                 \
  89         ipc_unlock(&(shp)->shm_perm)
  90
  91 static int newseg(struct ipc_namespace *, struct ipc_params *);
  92 static void shm_open(struct vm_area_struct *vma);
  93 static void shm_close(struct vm_area_struct *vma);
  94 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
  95 #ifdef CONFIG_PROC_FS
  96 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  97 #endif
  98
  99 void shm_init_ns(struct ipc_namespace *ns)
 100 {
 101         ns->shm_ctlmax = SHMMAX;
 102         ns->shm_ctlall = SHMALL;
 103         ns->shm_ctlmni = SHMMNI;
 104         ns->shm_rmid_forced = 0;
 105         ns->shm_tot = 0;
 106         ipc_init_ids(&shm_ids(ns));
 107 }
 108
 109 /*
 110  * Called with shm_ids.rwsem (writer) and the shp structure locked.
 111  * Only shm_ids.rwsem remains locked on exit.
 112  */
 113 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 114 {
 115         struct shmid_kernel *shp;
 116
 117         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 118
 119         if (shp->shm_nattch) {
 120                 shp->shm_perm.mode |= SHM_DEST;
 121                 /* Do not find it any more */
 122                 ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
 123                 shm_unlock(shp);
 124         } else
 125                 shm_destroy(ns, shp);
 126 }
 127
 128 #ifdef CONFIG_IPC_NS
 129 void shm_exit_ns(struct ipc_namespace *ns)
 130 {
 131         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 132         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 133         rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
 134 }
 135 #endif
 136
 137 static int __init ipc_ns_init(void)
 138 {
 139         shm_init_ns(&init_ipc_ns);
 140         return 0;
 141 }
 142
 143 pure_initcall(ipc_ns_init);
 144
 145 void __init shm_init(void)
 146 {
 147         ipc_init_proc_interface("sysvipc/shm",
 148 #if BITS_PER_LONG <= 32
 149                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 150 #else
 151                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 152 #endif
 153                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 154 }
 155
 156 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 157 {
 158         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 159
 160         if (IS_ERR(ipcp))
 161                 return ERR_CAST(ipcp);
 162
 163         return container_of(ipcp, struct shmid_kernel, shm_perm);
 164 }
 165
 166 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 167 {
 168         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 169
 170         if (IS_ERR(ipcp))
 171                 return ERR_CAST(ipcp);
 172
 173         return container_of(ipcp, struct shmid_kernel, shm_perm);
 174 }
 175
 176 /*
 177  * shm_lock_(check_) routines are called in the paths where the rwsem
 178  * is not necessarily held.
 179  */
 180 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 181 {
 182         struct kern_ipc_perm *ipcp;
 183
 184         rcu_read_lock();
 185         ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 186         if (IS_ERR(ipcp))
 187                 goto err;
 188
 189         ipc_lock_object(ipcp);
 190         /*
 191          * ipc_rmid() may have already freed the ID while ipc_lock_object()
 192          * was spinning: here verify that the structure is still valid.
 193          * Upon races with RMID, return -EIDRM, thus indicating that
 194          * the ID points to a removed identifier.
 195          */
 196         if (ipc_valid_object(ipcp)) {
 197                 /* return a locked ipc object upon success */
 198                 return container_of(ipcp, struct shmid_kernel, shm_perm);
 199         }
 200
 201         ipc_unlock_object(ipcp);
 202 err:
 203         rcu_read_unlock();
 204         /*
 205          * Callers of shm_lock() must validate the status of the returned ipc
 206          * object pointer and error out as appropriate.
 207          */
 208         return (void *)ipcp;
 209 }
 210
 211 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 212 {
 213         rcu_read_lock();
 214         ipc_lock_object(&ipcp->shm_perm);
 215 }
 216
 217 static void shm_rcu_free(struct rcu_head *head)
 218 {
 219         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
 220                                                         rcu);
 221         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
 222                                                         shm_perm);
 223         security_shm_free(&shp->shm_perm);
 224         kvfree(shp);
 225 }
 226
 227 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 228 {
 229         list_del(&s->shm_clist);
 230         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 231 }
 232
 233
 234 static int __shm_open(struct vm_area_struct *vma)
 235 {
 236         struct file *file = vma->vm_file;
 237         struct shm_file_data *sfd = shm_file_data(file);
 238         struct shmid_kernel *shp;
 239
 240         shp = shm_lock(sfd->ns, sfd->id);
 241
 242         if (IS_ERR(shp))
 243                 return PTR_ERR(shp);
 244
 245         if (shp->shm_file != sfd->file) {
 246                 /* ID was reused */
 247                 shm_unlock(shp);
 248                 return -EINVAL;
 249         }
 250
 251         shp->shm_atim = ktime_get_real_seconds();
 252         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 253         shp->shm_nattch++;
 254         shm_unlock(shp);
 255         return 0;
 256 }
 257
 258 /* This is called by fork, once for every shm attach. */
 259 static void shm_open(struct vm_area_struct *vma)
 260 {
 261         int err = __shm_open(vma);
 262         /*
 263          * We raced in the idr lookup or with shm_destroy().
 264          * Either way, the ID is busted.
 265          */
 266         WARN_ON_ONCE(err);
 267 }
 268
 269 /*
 270  * shm_destroy - free the struct shmid_kernel
 271  *
 272  * @ns: namespace
 273  * @shp: struct to free
 274  *
 275  * It has to be called with shp and shm_ids.rwsem (writer) locked,
 276  * but returns with shp unlocked and freed.
 277  */
 278 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 279 {
 280         struct file *shm_file;
 281
 282         shm_file = shp->shm_file;
 283         shp->shm_file = NULL;
 284         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 285         shm_rmid(ns, shp);
 286         shm_unlock(shp);
 287         if (!is_file_hugepages(shm_file))
 288                 shmem_lock(shm_file, 0, shp->mlock_user);
 289         else if (shp->mlock_user)
 290                 user_shm_unlock(i_size_read(file_inode(shm_file)),
 291                                 shp->mlock_user);
 292         fput(shm_file);
 293         ipc_update_pid(&shp->shm_cprid, NULL);
 294         ipc_update_pid(&shp->shm_lprid, NULL);
 295         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 296 }
 297
 298 /*
 299  * shm_may_destroy - identifies whether shm segment should be destroyed now
 300  *
 301  * Returns true if and only if there are no active users of the segment and
 302  * one of the following is true:
 303  *
 304  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 305  *
 306  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 307  */
 308 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 309 {
 310         return (shp->shm_nattch == 0) &&
 311                (ns->shm_rmid_forced ||
 312                 (shp->shm_perm.mode & SHM_DEST));
 313 }
 314
 315 /*
 316  * remove the attach descriptor vma.
 317  * free memory for segment if it is marked destroyed.
 318  * The descriptor has already been removed from the current->mm->mmap list
 319  * and will later be kfree()d.
 320  */
 321 static void shm_close(struct vm_area_struct *vma)
 322 {
 323         struct file *file = vma->vm_file;
 324         struct shm_file_data *sfd = shm_file_data(file);
 325         struct shmid_kernel *shp;
 326         struct ipc_namespace *ns = sfd->ns;
 327
 328         down_write(&shm_ids(ns).rwsem);
 329         /* remove from the list of attaches of the shm segment */
 330         shp = shm_lock(ns, sfd->id);
 331
 332         /*
 333          * We raced in the idr lookup or with shm_destroy().
 334          * Either way, the ID is busted.
 335          */
 336         if (WARN_ON_ONCE(IS_ERR(shp)))
 337                 goto done; /* no-op */
 338
 339         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 340         shp->shm_dtim = ktime_get_real_seconds();
 341         shp->shm_nattch--;
 342         if (shm_may_destroy(ns, shp))
 343                 shm_destroy(ns, shp);
 344         else
 345                 shm_unlock(shp);
 346 done:
 347         up_write(&shm_ids(ns).rwsem);
 348 }
 349
 350 /* Called with ns->shm_ids(ns).rwsem locked */
 351 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 352 {
 353         struct ipc_namespace *ns = data;
 354         struct kern_ipc_perm *ipcp = p;
 355         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 356
 357         /*
 358          * We want to destroy segments without users and with already
 359          * exit'ed originating process.
 360          *
 361          * As shp->* are changed under rwsem, it's safe to skip shp locking.
 362          */
 363         if (shp->shm_creator != NULL)
 364                 return 0;
 365
 366         if (shm_may_destroy(ns, shp)) {
 367                 shm_lock_by_ptr(shp);
 368                 shm_destroy(ns, shp);
 369         }
 370         return 0;
 371 }
 372
 373 void shm_destroy_orphaned(struct ipc_namespace *ns)
 374 {
 375         down_write(&shm_ids(ns).rwsem);
 376         if (shm_ids(ns).in_use)
 377                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 378         up_write(&shm_ids(ns).rwsem);
 379 }
 380
 381 /* Locking assumes this will only be called with task == current */
 382 void exit_shm(struct task_struct *task)
 383 {
 384         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 385         struct shmid_kernel *shp, *n;
 386
 387         if (list_empty(&task->sysvshm.shm_clist))
 388                 return;
 389
 390         /*
 391          * If kernel.shm_rmid_forced is not set then only keep track of
 392          * which shmids are orphaned, so that a later set of the sysctl
 393          * can clean them up.
 394          */
 395         if (!ns->shm_rmid_forced) {
 396                 down_read(&shm_ids(ns).rwsem);
 397                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
 398                         shp->shm_creator = NULL;
 399                 /*
 400                  * Only under read lock but we are only called on current
 401                  * so no entry on the list will be shared.
 402                  */
 403                 list_del(&task->sysvshm.shm_clist);
 404                 up_read(&shm_ids(ns).rwsem);
 405                 return;
 406         }
 407
 408         /*
 409          * Destroy all already created segments, that were not yet mapped,
 410          * and mark any mapped as orphan to cover the sysctl toggling.
 411          * Destroy is skipped if shm_may_destroy() returns false.
 412          */
 413         down_write(&shm_ids(ns).rwsem);
 414         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
 415                 shp->shm_creator = NULL;
 416
 417                 if (shm_may_destroy(ns, shp)) {
 418                         shm_lock_by_ptr(shp);
 419                         shm_destroy(ns, shp);
 420                 }
 421         }
 422
 423         /* Remove the list head from any segments still attached. */
 424         list_del(&task->sysvshm.shm_clist);
 425         up_write(&shm_ids(ns).rwsem);
 426 }
 427
 428 static vm_fault_t shm_fault(struct vm_fault *vmf)
 429 {
 430         struct file *file = vmf->vma->vm_file;
 431         struct shm_file_data *sfd = shm_file_data(file);
 432
 433         return sfd->vm_ops->fault(vmf);
 434 }
 435
 436 static int shm_split(struct vm_area_struct *vma, unsigned long addr)
 437 {
 438         struct file *file = vma->vm_file;
 439         struct shm_file_data *sfd = shm_file_data(file);
 440
 441         if (sfd->vm_ops->split)
 442                 return sfd->vm_ops->split(vma, addr);
 443
 444         return 0;
 445 }
 446
 447 static unsigned long shm_pagesize(struct vm_area_struct *vma)
 448 {
 449         struct file *file = vma->vm_file;
 450         struct shm_file_data *sfd = shm_file_data(file);
 451
 452         if (sfd->vm_ops->pagesize)
 453                 return sfd->vm_ops->pagesize(vma);
 454
 455         return PAGE_SIZE;
 456 }
 457
 458 #ifdef CONFIG_NUMA
 459 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 460 {
 461         struct file *file = vma->vm_file;
 462         struct shm_file_data *sfd = shm_file_data(file);
 463         int err = 0;
 464
 465         if (sfd->vm_ops->set_policy)
 466                 err = sfd->vm_ops->set_policy(vma, new);
 467         return err;
 468 }
 469
 470 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 471                                         unsigned long addr)
 472 {
 473         struct file *file = vma->vm_file;
 474         struct shm_file_data *sfd = shm_file_data(file);
 475         struct mempolicy *pol = NULL;
 476
 477         if (sfd->vm_ops->get_policy)
 478                 pol = sfd->vm_ops->get_policy(vma, addr);
 479         else if (vma->vm_policy)
 480                 pol = vma->vm_policy;
 481
 482         return pol;
 483 }
 484 #endif
 485
 486 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 487 {
 488         struct shm_file_data *sfd = shm_file_data(file);
 489         int ret;
 490
 491         /*
 492          * In case of remap_file_pages() emulation, the file can represent an
 493          * IPC ID that was removed, and possibly even reused by another shm
 494          * segment already.  Propagate this case as an error to caller.
 495          */
 496         ret = __shm_open(vma);
 497         if (ret)
 498                 return ret;
 499
 500         ret = call_mmap(sfd->file, vma);
 501         if (ret) {
 502                 shm_close(vma);
 503                 return ret;
 504         }
 505         sfd->vm_ops = vma->vm_ops;
 506 #ifdef CONFIG_MMU
 507         WARN_ON(!sfd->vm_ops->fault);
 508 #endif
 509         vma->vm_ops = &shm_vm_ops;
 510         return 0;
 511 }
 512
 513 static int shm_release(struct inode *ino, struct file *file)
 514 {
 515         struct shm_file_data *sfd = shm_file_data(file);
 516
 517         put_ipc_ns(sfd->ns);
 518         fput(sfd->file);
 519         shm_file_data(file) = NULL;
 520         kfree(sfd);
 521         return 0;
 522 }
 523
 524 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 525 {
 526         struct shm_file_data *sfd = shm_file_data(file);
 527
 528         if (!sfd->file->f_op->fsync)
 529                 return -EINVAL;
 530         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 531 }
 532
 533 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 534                           loff_t len)
 535 {
 536         struct shm_file_data *sfd = shm_file_data(file);
 537
 538         if (!sfd->file->f_op->fallocate)
 539                 return -EOPNOTSUPP;
 540         return sfd->file->f_op->fallocate(file, mode, offset, len);
 541 }
 542
 543 static unsigned long shm_get_unmapped_area(struct file *file,
 544         unsigned long addr, unsigned long len, unsigned long pgoff,
 545         unsigned long flags)
 546 {
 547         struct shm_file_data *sfd = shm_file_data(file);
 548
 549         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 550                                                 pgoff, flags);
 551 }
 552
 553 static const struct file_operations shm_file_operations = {
 554         .mmap           = shm_mmap,
 555         .fsync          = shm_fsync,
 556         .release        = shm_release,
 557         .get_unmapped_area      = shm_get_unmapped_area,
 558         .llseek         = noop_llseek,
 559         .fallocate      = shm_fallocate,
 560 };
 561
 562 /*
 563  * shm_file_operations_huge is now identical to shm_file_operations,
 564  * but we keep it distinct for the sake of is_file_shm_hugepages().
 565  */
 566 static const struct file_operations shm_file_operations_huge = {
 567         .mmap           = shm_mmap,
 568         .fsync          = shm_fsync,
 569         .release        = shm_release,
 570         .get_unmapped_area      = shm_get_unmapped_area,
 571         .llseek         = noop_llseek,
 572         .fallocate      = shm_fallocate,
 573 };
 574
 575 bool is_file_shm_hugepages(struct file *file)
 576 {
 577         return file->f_op == &shm_file_operations_huge;
 578 }
 579
 580 static const struct vm_operations_struct shm_vm_ops = {
 581         .open   = shm_open,     /* callback for a new vm-area open */
 582         .close  = shm_close,    /* callback for when the vm-area is released */
 583         .fault  = shm_fault,
 584         .split  = shm_split,
 585         .pagesize = shm_pagesize,
 586 #if defined(CONFIG_NUMA)
 587         .set_policy = shm_set_policy,
 588         .get_policy = shm_get_policy,
 589 #endif
 590 };
 591
 592 /**
 593  * newseg - Create a new shared memory segment
 594  * @ns: namespace
 595  * @params: ptr to the structure that contains key, size and shmflg
 596  *
 597  * Called with shm_ids.rwsem held as a writer.
 598  */
 599 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 600 {
 601         key_t key = params->key;
 602         int shmflg = params->flg;
 603         size_t size = params->u.size;
 604         int error;
 605         struct shmid_kernel *shp;
 606         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 607         struct file *file;
 608         char name[13];
 609         vm_flags_t acctflag = 0;
 610
 611         if (size < SHMMIN || size > ns->shm_ctlmax)
 612                 return -EINVAL;
 613
 614         if (numpages << PAGE_SHIFT < size)
 615                 return -ENOSPC;
 616
 617         if (ns->shm_tot + numpages < ns->shm_tot ||
 618                         ns->shm_tot + numpages > ns->shm_ctlall)
 619                 return -ENOSPC;
 620
 621         shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
 622         if (unlikely(!shp))
 623                 return -ENOMEM;
 624
 625         shp->shm_perm.key = key;
 626         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 627         shp->mlock_user = NULL;
 628
 629         shp->shm_perm.security = NULL;
 630         error = security_shm_alloc(&shp->shm_perm);
 631         if (error) {
 632                 kvfree(shp);
 633                 return error;
 634         }
 635
 636         sprintf(name, "SYSV%08x", key);
 637         if (shmflg & SHM_HUGETLB) {
 638                 struct hstate *hs;
 639                 size_t hugesize;
 640
 641                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 642                 if (!hs) {
 643                         error = -EINVAL;
 644                         goto no_file;
 645                 }
 646                 hugesize = ALIGN(size, huge_page_size(hs));
 647
 648                 /* hugetlb_file_setup applies strict accounting */
 649                 if (shmflg & SHM_NORESERVE)
 650                         acctflag = VM_NORESERVE;
 651                 file = hugetlb_file_setup(name, hugesize, acctflag,
 652                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
 653                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 654         } else {
 655                 /*
 656                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 657                  * if it's asked for.
 658                  */
 659                 if  ((shmflg & SHM_NORESERVE) &&
 660                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 661                         acctflag = VM_NORESERVE;
 662                 file = shmem_kernel_file_setup(name, size, acctflag);
 663         }
 664         error = PTR_ERR(file);
 665         if (IS_ERR(file))
 666                 goto no_file;
 667
 668         shp->shm_cprid = get_pid(task_tgid(current));
 669         shp->shm_lprid = NULL;
 670         shp->shm_atim = shp->shm_dtim = 0;
 671         shp->shm_ctim = ktime_get_real_seconds();
 672         shp->shm_segsz = size;
 673         shp->shm_nattch = 0;
 674         shp->shm_file = file;
 675         shp->shm_creator = current;
 676
 677         /* ipc_addid() locks shp upon success. */
 678         error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 679         if (error < 0)
 680                 goto no_id;
 681
 682         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 683
 684         /*
 685          * shmid gets reported as "inode#" in /proc/pid/maps.
 686          * proc-ps tools use this. Changing this will break them.
 687          */
 688         file_inode(file)->i_ino = shp->shm_perm.id;
 689
 690         ns->shm_tot += numpages;
 691         error = shp->shm_perm.id;
 692
 693         ipc_unlock_object(&shp->shm_perm);
 694         rcu_read_unlock();
 695         return error;
 696
 697 no_id:
 698         ipc_update_pid(&shp->shm_cprid, NULL);
 699         ipc_update_pid(&shp->shm_lprid, NULL);
 700         if (is_file_hugepages(file) && shp->mlock_user)
 701                 user_shm_unlock(size, shp->mlock_user);
 702         fput(file);
 703         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 704         return error;
 705 no_file:
 706         call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
 707         return error;
 708 }
 709
 710 /*
 711  * Called with shm_ids.rwsem and ipcp locked.
 712  */
 713 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 714                                 struct ipc_params *params)
 715 {
 716         struct shmid_kernel *shp;
 717
 718         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 719         if (shp->shm_segsz < params->u.size)
 720                 return -EINVAL;
 721
 722         return 0;
 723 }
 724
 725 long ksys_shmget(key_t key, size_t size, int shmflg)
 726 {
 727         struct ipc_namespace *ns;
 728         static const struct ipc_ops shm_ops = {
 729                 .getnew = newseg,
 730                 .associate = security_shm_associate,
 731                 .more_checks = shm_more_checks,
 732         };
 733         struct ipc_params shm_params;
 734
 735         ns = current->nsproxy->ipc_ns;
 736
 737         shm_params.key = key;
 738         shm_params.flg = shmflg;
 739         shm_params.u.size = size;
 740
 741         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 742 }
 743
 744 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 745 {
 746         return ksys_shmget(key, size, shmflg);
 747 }
 748
 749 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 750 {
 751         switch (version) {
 752         case IPC_64:
 753                 return copy_to_user(buf, in, sizeof(*in));
 754         case IPC_OLD:
 755             {
 756                 struct shmid_ds out;
 757
 758                 memset(&out, 0, sizeof(out));
 759                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 760                 out.shm_segsz   = in->shm_segsz;
 761                 out.shm_atime   = in->shm_atime;
 762                 out.shm_dtime   = in->shm_dtime;
 763                 out.shm_ctime   = in->shm_ctime;
 764                 out.shm_cpid    = in->shm_cpid;
 765                 out.shm_lpid    = in->shm_lpid;
 766                 out.shm_nattch  = in->shm_nattch;
 767
 768                 return copy_to_user(buf, &out, sizeof(out));
 769             }
 770         default:
 771                 return -EINVAL;
 772         }
 773 }
 774
 775 static inline unsigned long
 776 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 777 {
 778         switch (version) {
 779         case IPC_64:
 780                 if (copy_from_user(out, buf, sizeof(*out)))
 781                         return -EFAULT;
 782                 return 0;
 783         case IPC_OLD:
 784             {
 785                 struct shmid_ds tbuf_old;
 786
 787                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 788                         return -EFAULT;
 789
 790                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 791                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 792                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 793
 794                 return 0;
 795             }
 796         default:
 797                 return -EINVAL;
 798         }
 799 }
 800
 801 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 802 {
 803         switch (version) {
 804         case IPC_64:
 805                 return copy_to_user(buf, in, sizeof(*in));
 806         case IPC_OLD:
 807             {
 808                 struct shminfo out;
 809
 810                 if (in->shmmax > INT_MAX)
 811                         out.shmmax = INT_MAX;
 812                 else
 813                         out.shmmax = (int)in->shmmax;
 814
 815                 out.shmmin      = in->shmmin;
 816                 out.shmmni      = in->shmmni;
 817                 out.shmseg      = in->shmseg;
 818                 out.shmall      = in->shmall;
 819
 820                 return copy_to_user(buf, &out, sizeof(out));
 821             }
 822         default:
 823                 return -EINVAL;
 824         }
 825 }
 826
 827 /*
 828  * Calculate and add used RSS and swap pages of a shm.
 829  * Called with shm_ids.rwsem held as a reader
 830  */
 831 static void shm_add_rss_swap(struct shmid_kernel *shp,
 832         unsigned long *rss_add, unsigned long *swp_add)
 833 {
 834         struct inode *inode;
 835
 836         inode = file_inode(shp->shm_file);
 837
 838         if (is_file_hugepages(shp->shm_file)) {
 839                 struct address_space *mapping = inode->i_mapping;
 840                 struct hstate *h = hstate_file(shp->shm_file);
 841                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 842         } else {
 843 #ifdef CONFIG_SHMEM
 844                 struct shmem_inode_info *info = SHMEM_I(inode);
 845
 846                 spin_lock_irq(&info->lock);
 847                 *rss_add += inode->i_mapping->nrpages;
 848                 *swp_add += info->swapped;
 849                 spin_unlock_irq(&info->lock);
 850 #else
 851                 *rss_add += inode->i_mapping->nrpages;
 852 #endif
 853         }
 854 }
 855
 856 /*
 857  * Called with shm_ids.rwsem held as a reader
 858  */
 859 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 860                 unsigned long *swp)
 861 {
 862         int next_id;
 863         int total, in_use;
 864
 865         *rss = 0;
 866         *swp = 0;
 867
 868         in_use = shm_ids(ns).in_use;
 869
 870         for (total = 0, next_id = 0; total < in_use; next_id++) {
 871                 struct kern_ipc_perm *ipc;
 872                 struct shmid_kernel *shp;
 873
 874                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 875                 if (ipc == NULL)
 876                         continue;
 877                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 878
 879                 shm_add_rss_swap(shp, rss, swp);
 880
 881                 total++;
 882         }
 883 }
 884
 885 /*
 886  * This function handles some shmctl commands which require the rwsem
 887  * to be held in write mode.
 888  * NOTE: no locks must be held, the rwsem is taken inside this function.
 889  */
 890 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 891                        struct shmid64_ds *shmid64)
 892 {
 893         struct kern_ipc_perm *ipcp;
 894         struct shmid_kernel *shp;
 895         int err;
 896
 897         down_write(&shm_ids(ns).rwsem);
 898         rcu_read_lock();
 899
 900         ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
 901                                       &shmid64->shm_perm, 0);
 902         if (IS_ERR(ipcp)) {
 903                 err = PTR_ERR(ipcp);
 904                 goto out_unlock1;
 905         }
 906
 907         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 908
 909         err = security_shm_shmctl(&shp->shm_perm, cmd);
 910         if (err)
 911                 goto out_unlock1;
 912
 913         switch (cmd) {
 914         case IPC_RMID:
 915                 ipc_lock_object(&shp->shm_perm);
 916                 /* do_shm_rmid unlocks the ipc object and rcu */
 917                 do_shm_rmid(ns, ipcp);
 918                 goto out_up;
 919         case IPC_SET:
 920                 ipc_lock_object(&shp->shm_perm);
 921                 err = ipc_update_perm(&shmid64->shm_perm, ipcp);
 922                 if (err)
 923                         goto out_unlock0;
 924                 shp->shm_ctim = ktime_get_real_seconds();
 925                 break;
 926         default:
 927                 err = -EINVAL;
 928                 goto out_unlock1;
 929         }
 930
 931 out_unlock0:
 932         ipc_unlock_object(&shp->shm_perm);
 933 out_unlock1:
 934         rcu_read_unlock();
 935 out_up:
 936         up_write(&shm_ids(ns).rwsem);
 937         return err;
 938 }
 939
 940 static int shmctl_ipc_info(struct ipc_namespace *ns,
 941                            struct shminfo64 *shminfo)
 942 {
 943         int err = security_shm_shmctl(NULL, IPC_INFO);
 944         if (!err) {
 945                 memset(shminfo, 0, sizeof(*shminfo));
 946                 shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
 947                 shminfo->shmmax = ns->shm_ctlmax;
 948                 shminfo->shmall = ns->shm_ctlall;
 949                 shminfo->shmmin = SHMMIN;
 950                 down_read(&shm_ids(ns).rwsem);
 951                 err = ipc_get_maxidx(&shm_ids(ns));
 952                 up_read(&shm_ids(ns).rwsem);
 953                 if (err < 0)
 954                         err = 0;
 955         }
 956         return err;
 957 }
 958
 959 static int shmctl_shm_info(struct ipc_namespace *ns,
 960                            struct shm_info *shm_info)
 961 {
 962         int err = security_shm_shmctl(NULL, SHM_INFO);
 963         if (!err) {
 964                 memset(shm_info, 0, sizeof(*shm_info));
 965                 down_read(&shm_ids(ns).rwsem);
 966                 shm_info->used_ids = shm_ids(ns).in_use;
 967                 shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
 968                 shm_info->shm_tot = ns->shm_tot;
 969                 shm_info->swap_attempts = 0;
 970                 shm_info->swap_successes = 0;
 971                 err = ipc_get_maxidx(&shm_ids(ns));
 972                 up_read(&shm_ids(ns).rwsem);
 973                 if (err < 0)
 974                         err = 0;
 975         }
 976         return err;
 977 }
 978
 979 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
 980                         int cmd, struct shmid64_ds *tbuf)
 981 {
 982         struct shmid_kernel *shp;
 983         int err;
 984
 985         memset(tbuf, 0, sizeof(*tbuf));
 986
 987         rcu_read_lock();
 988         if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
 989                 shp = shm_obtain_object(ns, shmid);
 990                 if (IS_ERR(shp)) {
 991                         err = PTR_ERR(shp);
 992                         goto out_unlock;
 993                 }
 994         } else { /* IPC_STAT */
 995                 shp = shm_obtain_object_check(ns, shmid);
 996                 if (IS_ERR(shp)) {
 997                         err = PTR_ERR(shp);
 998                         goto out_unlock;
 999                 }
1000         }
1001
1002         /*
1003          * Semantically SHM_STAT_ANY ought to be identical to
1004          * that functionality provided by the /proc/sysvipc/
1005          * interface. As such, only audit these calls and
1006          * do not do traditional S_IRUGO permission checks on
1007          * the ipc object.
1008          */
1009         if (cmd == SHM_STAT_ANY)
1010                 audit_ipc_obj(&shp->shm_perm);
1011         else {
1012                 err = -EACCES;
1013                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
1014                         goto out_unlock;
1015         }
1016
1017         err = security_shm_shmctl(&shp->shm_perm, cmd);
1018         if (err)
1019                 goto out_unlock;
1020
1021         ipc_lock_object(&shp->shm_perm);
1022
1023         if (!ipc_valid_object(&shp->shm_perm)) {
1024                 ipc_unlock_object(&shp->shm_perm);
1025                 err = -EIDRM;
1026                 goto out_unlock;
1027         }
1028
1029         kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1030         tbuf->shm_segsz = shp->shm_segsz;
1031         tbuf->shm_atime = shp->shm_atim;
1032         tbuf->shm_dtime = shp->shm_dtim;
1033         tbuf->shm_ctime = shp->shm_ctim;
1034 #ifndef CONFIG_64BIT
1035         tbuf->shm_atime_high = shp->shm_atim >> 32;
1036         tbuf->shm_dtime_high = shp->shm_dtim >> 32;
1037         tbuf->shm_ctime_high = shp->shm_ctim >> 32;
1038 #endif
1039         tbuf->shm_cpid  = pid_vnr(shp->shm_cprid);
1040         tbuf->shm_lpid  = pid_vnr(shp->shm_lprid);
1041         tbuf->shm_nattch = shp->shm_nattch;
1042
1043         if (cmd == IPC_STAT) {
1044                 /*
1045                  * As defined in SUS:
1046                  * Return 0 on success
1047                  */
1048                 err = 0;
1049         } else {
1050                 /*
1051                  * SHM_STAT and SHM_STAT_ANY (both Linux specific)
1052                  * Return the full id, including the sequence number
1053                  */
1054                 err = shp->shm_perm.id;
1055         }
1056
1057         ipc_unlock_object(&shp->shm_perm);
1058 out_unlock:
1059         rcu_read_unlock();
1060         return err;
1061 }
1062
1063 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1064 {
1065         struct shmid_kernel *shp;
1066         struct file *shm_file;
1067         int err;
1068
1069         rcu_read_lock();
1070         shp = shm_obtain_object_check(ns, shmid);
1071         if (IS_ERR(shp)) {
1072                 err = PTR_ERR(shp);
1073                 goto out_unlock1;
1074         }
1075
1076         audit_ipc_obj(&(shp->shm_perm));
1077         err = security_shm_shmctl(&shp->shm_perm, cmd);
1078         if (err)
1079                 goto out_unlock1;
1080
1081         ipc_lock_object(&shp->shm_perm);
1082
1083         /* check if shm_destroy() is tearing down shp */
1084         if (!ipc_valid_object(&shp->shm_perm)) {
1085                 err = -EIDRM;
1086                 goto out_unlock0;
1087         }
1088
1089         if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1090                 kuid_t euid = current_euid();
1091
1092                 if (!uid_eq(euid, shp->shm_perm.uid) &&
1093                     !uid_eq(euid, shp->shm_perm.cuid)) {
1094                         err = -EPERM;
1095                         goto out_unlock0;
1096                 }
1097                 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1098                         err = -EPERM;
1099                         goto out_unlock0;
1100                 }
1101         }
1102
1103         shm_file = shp->shm_file;
1104         if (is_file_hugepages(shm_file))
1105                 goto out_unlock0;
1106
1107         if (cmd == SHM_LOCK) {
1108                 struct user_struct *user = current_user();
1109
1110                 err = shmem_lock(shm_file, 1, user);
1111                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1112                         shp->shm_perm.mode |= SHM_LOCKED;
1113                         shp->mlock_user = user;
1114                 }
1115                 goto out_unlock0;
1116         }
1117
1118         /* SHM_UNLOCK */
1119         if (!(shp->shm_perm.mode & SHM_LOCKED))
1120                 goto out_unlock0;
1121         shmem_lock(shm_file, 0, shp->mlock_user);
1122         shp->shm_perm.mode &= ~SHM_LOCKED;
1123         shp->mlock_user = NULL;
1124         get_file(shm_file);
1125         ipc_unlock_object(&shp->shm_perm);
1126         rcu_read_unlock();
1127         shmem_unlock_mapping(shm_file->f_mapping);
1128
1129         fput(shm_file);
1130         return err;
1131
1132 out_unlock0:
1133         ipc_unlock_object(&shp->shm_perm);
1134 out_unlock1:
1135         rcu_read_unlock();
1136         return err;
1137 }
1138
1139 long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1140 {
1141         int err, version;
1142         struct ipc_namespace *ns;
1143         struct shmid64_ds sem64;
1144
1145         if (cmd < 0 || shmid < 0)
1146                 return -EINVAL;
1147
1148         version = ipc_parse_version(&cmd);
1149         ns = current->nsproxy->ipc_ns;
1150
1151         switch (cmd) {
1152         case IPC_INFO: {
1153                 struct shminfo64 shminfo;
1154                 err = shmctl_ipc_info(ns, &shminfo);
1155                 if (err < 0)
1156                         return err;
1157                 if (copy_shminfo_to_user(buf, &shminfo, version))
1158                         err = -EFAULT;
1159                 return err;
1160         }
1161         case SHM_INFO: {
1162                 struct shm_info shm_info;
1163                 err = shmctl_shm_info(ns, &shm_info);
1164                 if (err < 0)
1165                         return err;
1166                 if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1167                         err = -EFAULT;
1168                 return err;
1169         }
1170         case SHM_STAT:
1171         case SHM_STAT_ANY:
1172         case IPC_STAT: {
1173                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1174                 if (err < 0)
1175                         return err;
1176                 if (copy_shmid_to_user(buf, &sem64, version))
1177                         err = -EFAULT;
1178                 return err;
1179         }
1180         case IPC_SET:
1181                 if (copy_shmid_from_user(&sem64, buf, version))
1182                         return -EFAULT;
1183                 /* fallthru */
1184         case IPC_RMID:
1185                 return shmctl_down(ns, shmid, cmd, &sem64);
1186         case SHM_LOCK:
1187         case SHM_UNLOCK:
1188                 return shmctl_do_lock(ns, shmid, cmd);
1189         default:
1190                 return -EINVAL;
1191         }
1192 }
1193
1194 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1195 {
1196         return ksys_shmctl(shmid, cmd, buf);
1197 }
1198
1199 #ifdef CONFIG_COMPAT
1200
1201 struct compat_shmid_ds {
1202         struct compat_ipc_perm shm_perm;
1203         int shm_segsz;
1204         compat_time_t shm_atime;
1205         compat_time_t shm_dtime;
1206         compat_time_t shm_ctime;
1207         compat_ipc_pid_t shm_cpid;
1208         compat_ipc_pid_t shm_lpid;
1209         unsigned short shm_nattch;
1210         unsigned short shm_unused;
1211         compat_uptr_t shm_unused2;
1212         compat_uptr_t shm_unused3;
1213 };
1214
1215 struct compat_shminfo64 {
1216         compat_ulong_t shmmax;
1217         compat_ulong_t shmmin;
1218         compat_ulong_t shmmni;
1219         compat_ulong_t shmseg;
1220         compat_ulong_t shmall;
1221         compat_ulong_t __unused1;
1222         compat_ulong_t __unused2;
1223         compat_ulong_t __unused3;
1224         compat_ulong_t __unused4;
1225 };
1226
1227 struct compat_shm_info {
1228         compat_int_t used_ids;
1229         compat_ulong_t shm_tot, shm_rss, shm_swp;
1230         compat_ulong_t swap_attempts, swap_successes;
1231 };
1232
1233 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1234                                         int version)
1235 {
1236         if (in->shmmax > INT_MAX)
1237                 in->shmmax = INT_MAX;
1238         if (version == IPC_64) {
1239                 struct compat_shminfo64 info;
1240                 memset(&info, 0, sizeof(info));
1241                 info.shmmax = in->shmmax;
1242                 info.shmmin = in->shmmin;
1243                 info.shmmni = in->shmmni;
1244                 info.shmseg = in->shmseg;
1245                 info.shmall = in->shmall;
1246                 return copy_to_user(buf, &info, sizeof(info));
1247         } else {
1248                 struct shminfo info;
1249                 memset(&info, 0, sizeof(info));
1250                 info.shmmax = in->shmmax;
1251                 info.shmmin = in->shmmin;
1252                 info.shmmni = in->shmmni;
1253                 info.shmseg = in->shmseg;
1254                 info.shmall = in->shmall;
1255                 return copy_to_user(buf, &info, sizeof(info));
1256         }
1257 }
1258
1259 static int put_compat_shm_info(struct shm_info *ip,
1260                                 struct compat_shm_info __user *uip)
1261 {
1262         struct compat_shm_info info;
1263
1264         memset(&info, 0, sizeof(info));
1265         info.used_ids = ip->used_ids;
1266         info.shm_tot = ip->shm_tot;
1267         info.shm_rss = ip->shm_rss;
1268         info.shm_swp = ip->shm_swp;
1269         info.swap_attempts = ip->swap_attempts;
1270         info.swap_successes = ip->swap_successes;
1271         return copy_to_user(uip, &info, sizeof(info));
1272 }
1273
1274 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1275                                         int version)
1276 {
1277         if (version == IPC_64) {
1278                 struct compat_shmid64_ds v;
1279                 memset(&v, 0, sizeof(v));
1280                 to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1281                 v.shm_atime      = lower_32_bits(in->shm_atime);
1282                 v.shm_atime_high = upper_32_bits(in->shm_atime);
1283                 v.shm_dtime      = lower_32_bits(in->shm_dtime);
1284                 v.shm_dtime_high = upper_32_bits(in->shm_dtime);
1285                 v.shm_ctime      = lower_32_bits(in->shm_ctime);
1286                 v.shm_ctime_high = upper_32_bits(in->shm_ctime);
1287                 v.shm_segsz = in->shm_segsz;
1288                 v.shm_nattch = in->shm_nattch;
1289                 v.shm_cpid = in->shm_cpid;
1290                 v.shm_lpid = in->shm_lpid;
1291                 return copy_to_user(buf, &v, sizeof(v));
1292         } else {
1293                 struct compat_shmid_ds v;
1294                 memset(&v, 0, sizeof(v));
1295                 to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1296                 v.shm_perm.key = in->shm_perm.key;
1297                 v.shm_atime = in->shm_atime;
1298                 v.shm_dtime = in->shm_dtime;
1299                 v.shm_ctime = in->shm_ctime;
1300                 v.shm_segsz = in->shm_segsz;
1301                 v.shm_nattch = in->shm_nattch;
1302                 v.shm_cpid = in->shm_cpid;
1303                 v.shm_lpid = in->shm_lpid;
1304                 return copy_to_user(buf, &v, sizeof(v));
1305         }
1306 }
1307
1308 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1309                                         int version)
1310 {
1311         memset(out, 0, sizeof(*out));
1312         if (version == IPC_64) {
1313                 struct compat_shmid64_ds __user *p = buf;
1314                 return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1315         } else {
1316                 struct compat_shmid_ds __user *p = buf;
1317                 return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1318         }
1319 }
1320
1321 long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr)
1322 {
1323         struct ipc_namespace *ns;
1324         struct shmid64_ds sem64;
1325         int version = compat_ipc_parse_version(&cmd);
1326         int err;
1327
1328         ns = current->nsproxy->ipc_ns;
1329
1330         if (cmd < 0 || shmid < 0)
1331                 return -EINVAL;
1332
1333         switch (cmd) {
1334         case IPC_INFO: {
1335                 struct shminfo64 shminfo;
1336                 err = shmctl_ipc_info(ns, &shminfo);
1337                 if (err < 0)
1338                         return err;
1339                 if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1340                         err = -EFAULT;
1341                 return err;
1342         }
1343         case SHM_INFO: {
1344                 struct shm_info shm_info;
1345                 err = shmctl_shm_info(ns, &shm_info);
1346                 if (err < 0)
1347                         return err;
1348                 if (put_compat_shm_info(&shm_info, uptr))
1349                         err = -EFAULT;
1350                 return err;
1351         }
1352         case IPC_STAT:
1353         case SHM_STAT_ANY:
1354         case SHM_STAT:
1355                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1356                 if (err < 0)
1357                         return err;
1358                 if (copy_compat_shmid_to_user(uptr, &sem64, version))
1359                         err = -EFAULT;
1360                 return err;
1361
1362         case IPC_SET:
1363                 if (copy_compat_shmid_from_user(&sem64, uptr, version))
1364                         return -EFAULT;
1365                 /* fallthru */
1366         case IPC_RMID:
1367                 return shmctl_down(ns, shmid, cmd, &sem64);
1368         case SHM_LOCK:
1369         case SHM_UNLOCK:
1370                 return shmctl_do_lock(ns, shmid, cmd);
1371                 break;
1372         default:
1373                 return -EINVAL;
1374         }
1375         return err;
1376 }
1377
1378 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1379 {
1380         return compat_ksys_shmctl(shmid, cmd, uptr);
1381 }
1382 #endif
1383
1384 /*
1385  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1386  *
1387  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1388  * "raddr" thing points to kernel space, and there has to be a wrapper around
1389  * this.
1390  */
1391 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1392               ulong *raddr, unsigned long shmlba)
1393 {
1394         struct shmid_kernel *shp;
1395         unsigned long addr = (unsigned long)shmaddr;
1396         unsigned long size;
1397         struct file *file, *base;
1398         int    err;
1399         unsigned long flags = MAP_SHARED;
1400         unsigned long prot;
1401         int acc_mode;
1402         struct ipc_namespace *ns;
1403         struct shm_file_data *sfd;
1404         int f_flags;
1405         unsigned long populate = 0;
1406
1407         err = -EINVAL;
1408         if (shmid < 0)
1409                 goto out;
1410
1411         if (addr) {
1412                 if (addr & (shmlba - 1)) {
1413                         if (shmflg & SHM_RND) {
1414                                 addr &= ~(shmlba - 1);  /* round down */
1415
1416                                 /*
1417                                  * Ensure that the round-down is non-nil
1418                                  * when remapping. This can happen for
1419                                  * cases when addr < shmlba.
1420                                  */
1421                                 if (!addr && (shmflg & SHM_REMAP))
1422                                         goto out;
1423                         } else
1424 #ifndef __ARCH_FORCE_SHMLBA
1425                                 if (addr & ~PAGE_MASK)
1426 #endif
1427                                         goto out;
1428                 }
1429
1430                 flags |= MAP_FIXED;
1431         } else if ((shmflg & SHM_REMAP))
1432                 goto out;
1433
1434         if (shmflg & SHM_RDONLY) {
1435                 prot = PROT_READ;
1436                 acc_mode = S_IRUGO;
1437                 f_flags = O_RDONLY;
1438         } else {
1439                 prot = PROT_READ | PROT_WRITE;
1440                 acc_mode = S_IRUGO | S_IWUGO;
1441                 f_flags = O_RDWR;
1442         }
1443         if (shmflg & SHM_EXEC) {
1444                 prot |= PROT_EXEC;
1445                 acc_mode |= S_IXUGO;
1446         }
1447
1448         /*
1449          * We cannot rely on the fs check since SYSV IPC does have an
1450          * additional creator id...
1451          */
1452         ns = current->nsproxy->ipc_ns;
1453         rcu_read_lock();
1454         shp = shm_obtain_object_check(ns, shmid);
1455         if (IS_ERR(shp)) {
1456                 err = PTR_ERR(shp);
1457                 goto out_unlock;
1458         }
1459
1460         err = -EACCES;
1461         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1462                 goto out_unlock;
1463
1464         err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1465         if (err)
1466                 goto out_unlock;
1467
1468         ipc_lock_object(&shp->shm_perm);
1469
1470         /* check if shm_destroy() is tearing down shp */
1471         if (!ipc_valid_object(&shp->shm_perm)) {
1472                 ipc_unlock_object(&shp->shm_perm);
1473                 err = -EIDRM;
1474                 goto out_unlock;
1475         }
1476
1477         /*
1478          * We need to take a reference to the real shm file to prevent the
1479          * pointer from becoming stale in cases where the lifetime of the outer
1480          * file extends beyond that of the shm segment.  It's not usually
1481          * possible, but it can happen during remap_file_pages() emulation as
1482          * that unmaps the memory, then does ->mmap() via file reference only.
1483          * We'll deny the ->mmap() if the shm segment was since removed, but to
1484          * detect shm ID reuse we need to compare the file pointers.
1485          */
1486         base = get_file(shp->shm_file);
1487         shp->shm_nattch++;
1488         size = i_size_read(file_inode(base));
1489         ipc_unlock_object(&shp->shm_perm);
1490         rcu_read_unlock();
1491
1492         err = -ENOMEM;
1493         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1494         if (!sfd) {
1495                 fput(base);
1496                 goto out_nattch;
1497         }
1498
1499         file = alloc_file_clone(base, f_flags,
1500                           is_file_hugepages(base) ?
1501                                 &shm_file_operations_huge :
1502                                 &shm_file_operations);
1503         err = PTR_ERR(file);
1504         if (IS_ERR(file)) {
1505                 kfree(sfd);
1506                 fput(base);
1507                 goto out_nattch;
1508         }
1509
1510         sfd->id = shp->shm_perm.id;
1511         sfd->ns = get_ipc_ns(ns);
1512         sfd->file = base;
1513         sfd->vm_ops = NULL;
1514         file->private_data = sfd;
1515
1516         err = security_mmap_file(file, prot, flags);
1517         if (err)
1518                 goto out_fput;
1519
1520         if (down_write_killable(&current->mm->mmap_sem)) {
1521                 err = -EINTR;
1522                 goto out_fput;
1523         }
1524
1525         if (addr && !(shmflg & SHM_REMAP)) {
1526                 err = -EINVAL;
1527                 if (addr + size < addr)
1528                         goto invalid;
1529
1530                 if (find_vma_intersection(current->mm, addr, addr + size))
1531                         goto invalid;
1532         }
1533
1534         addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
1535         *raddr = addr;
1536         err = 0;
1537         if (IS_ERR_VALUE(addr))
1538                 err = (long)addr;
1539 invalid:
1540         up_write(&current->mm->mmap_sem);
1541         if (populate)
1542                 mm_populate(addr, populate);
1543
1544 out_fput:
1545         fput(file);
1546
1547 out_nattch:
1548         down_write(&shm_ids(ns).rwsem);
1549         shp = shm_lock(ns, shmid);
1550         shp->shm_nattch--;
1551         if (shm_may_destroy(ns, shp))
1552                 shm_destroy(ns, shp);
1553         else
1554                 shm_unlock(shp);
1555         up_write(&shm_ids(ns).rwsem);
1556         return err;
1557
1558 out_unlock:
1559         rcu_read_unlock();
1560 out:
1561         return err;
1562 }
1563
1564 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1565 {
1566         unsigned long ret;
1567         long err;
1568
1569         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1570         if (err)
1571                 return err;
1572         force_successful_syscall_return();
1573         return (long)ret;
1574 }
1575
1576 #ifdef CONFIG_COMPAT
1577
1578 #ifndef COMPAT_SHMLBA
1579 #define COMPAT_SHMLBA   SHMLBA
1580 #endif
1581
1582 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1583 {
1584         unsigned long ret;
1585         long err;
1586
1587         err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1588         if (err)
1589                 return err;
1590         force_successful_syscall_return();
1591         return (long)ret;
1592 }
1593 #endif
1594
1595 /*
1596  * detach and kill segment if marked destroyed.
1597  * The work is done in shm_close.
1598  */
1599 long ksys_shmdt(char __user *shmaddr)
1600 {
1601         struct mm_struct *mm = current->mm;
1602         struct vm_area_struct *vma;
1603         unsigned long addr = (unsigned long)shmaddr;
1604         int retval = -EINVAL;
1605 #ifdef CONFIG_MMU
1606         loff_t size = 0;
1607         struct file *file;
1608         struct vm_area_struct *next;
1609 #endif
1610
1611         if (addr & ~PAGE_MASK)
1612                 return retval;
1613
1614         if (down_write_killable(&mm->mmap_sem))
1615                 return -EINTR;
1616
1617         /*
1618          * This function tries to be smart and unmap shm segments that
1619          * were modified by partial mlock or munmap calls:
1620          * - It first determines the size of the shm segment that should be
1621          *   unmapped: It searches for a vma that is backed by shm and that
1622          *   started at address shmaddr. It records it's size and then unmaps
1623          *   it.
1624          * - Then it unmaps all shm vmas that started at shmaddr and that
1625          *   are within the initially determined size and that are from the
1626          *   same shm segment from which we determined the size.
1627          * Errors from do_munmap are ignored: the function only fails if
1628          * it's called with invalid parameters or if it's called to unmap
1629          * a part of a vma. Both calls in this function are for full vmas,
1630          * the parameters are directly copied from the vma itself and always
1631          * valid - therefore do_munmap cannot fail. (famous last words?)
1632          */
1633         /*
1634          * If it had been mremap()'d, the starting address would not
1635          * match the usual checks anyway. So assume all vma's are
1636          * above the starting address given.
1637          */
1638         vma = find_vma(mm, addr);
1639
1640 #ifdef CONFIG_MMU
1641         while (vma) {
1642                 next = vma->vm_next;
1643
1644                 /*
1645                  * Check if the starting address would match, i.e. it's
1646                  * a fragment created by mprotect() and/or munmap(), or it
1647                  * otherwise it starts at this address with no hassles.
1648                  */
1649                 if ((vma->vm_ops == &shm_vm_ops) &&
1650                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1651
1652                         /*
1653                          * Record the file of the shm segment being
1654                          * unmapped.  With mremap(), someone could place
1655                          * page from another segment but with equal offsets
1656                          * in the range we are unmapping.
1657                          */
1658                         file = vma->vm_file;
1659                         size = i_size_read(file_inode(vma->vm_file));
1660                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1661                         /*
1662                          * We discovered the size of the shm segment, so
1663                          * break out of here and fall through to the next
1664                          * loop that uses the size information to stop
1665                          * searching for matching vma's.
1666                          */
1667                         retval = 0;
1668                         vma = next;
1669                         break;
1670                 }
1671                 vma = next;
1672         }
1673
1674         /*
1675          * We need look no further than the maximum address a fragment
1676          * could possibly have landed at. Also cast things to loff_t to
1677          * prevent overflows and make comparisons vs. equal-width types.
1678          */
1679         size = PAGE_ALIGN(size);
1680         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1681                 next = vma->vm_next;
1682
1683                 /* finding a matching vma now does not alter retval */
1684                 if ((vma->vm_ops == &shm_vm_ops) &&
1685                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1686                     (vma->vm_file == file))
1687                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1688                 vma = next;
1689         }
1690
1691 #else   /* CONFIG_MMU */
1692         /* under NOMMU conditions, the exact address to be destroyed must be
1693          * given
1694          */
1695         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1696                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1697                 retval = 0;
1698         }
1699
1700 #endif
1701
1702         up_write(&mm->mmap_sem);
1703         return retval;
1704 }
1705
1706 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1707 {
1708         return ksys_shmdt(shmaddr);
1709 }
1710
1711 #ifdef CONFIG_PROC_FS
1712 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1713 {
1714         struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1715         struct user_namespace *user_ns = seq_user_ns(s);
1716         struct kern_ipc_perm *ipcp = it;
1717         struct shmid_kernel *shp;
1718         unsigned long rss = 0, swp = 0;
1719
1720         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1721         shm_add_rss_swap(shp, &rss, &swp);
1722
1723 #if BITS_PER_LONG <= 32
1724 #define SIZE_SPEC "%10lu"
1725 #else
1726 #define SIZE_SPEC "%21lu"
1727 #endif
1728
1729         seq_printf(s,
1730                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1731                    "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1732                    SIZE_SPEC " " SIZE_SPEC "\n",
1733                    shp->shm_perm.key,
1734                    shp->shm_perm.id,
1735                    shp->shm_perm.mode,
1736                    shp->shm_segsz,
1737                    pid_nr_ns(shp->shm_cprid, pid_ns),
1738                    pid_nr_ns(shp->shm_lprid, pid_ns),
1739                    shp->shm_nattch,
1740                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1741                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1742                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1743                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1744                    shp->shm_atim,
1745                    shp->shm_dtim,
1746                    shp->shm_ctim,
1747                    rss * PAGE_SIZE,
1748                    swp * PAGE_SIZE);
1749
1750         return 0;
1751 }
1752 #endif