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