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 #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 ucounts          *mlock_ucounts;
  64
  65         /*
  66          * The task created the shm object, for
  67          * task_lock(shp->shm_creator)
  68          */
  69         struct task_struct      *shm_creator;
  70
  71         /*
  72          * List by creator. task_lock(->shm_creator) required for read/write.
  73          * If list_empty(), then the creator is dead already.
  74          */
  75         struct list_head        shm_clist;
  76         struct ipc_namespace    *ns;
  77 } __randomize_layout;
  78
  79 /* shm_mode upper byte flags */
  80 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  81 #define SHM_LOCKED      02000   /* segment will not be swapped */
  82
  83 struct shm_file_data {
  84         int id;
  85         struct ipc_namespace *ns;
  86         struct file *file;
  87         const struct vm_operations_struct *vm_ops;
  88 };
  89
  90 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  91
  92 static const struct file_operations shm_file_operations;
  93 static const struct vm_operations_struct shm_vm_ops;
  94
  95 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
  96
  97 #define shm_unlock(shp)                 \
  98         ipc_unlock(&(shp)->shm_perm)
  99
 100 static int newseg(struct ipc_namespace *, struct ipc_params *);
 101 static void shm_open(struct vm_area_struct *vma);
 102 static void shm_close(struct vm_area_struct *vma);
 103 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
 104 #ifdef CONFIG_PROC_FS
 105 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
 106 #endif
 107
 108 void shm_init_ns(struct ipc_namespace *ns)
 109 {
 110         ns->shm_ctlmax = SHMMAX;
 111         ns->shm_ctlall = SHMALL;
 112         ns->shm_ctlmni = SHMMNI;
 113         ns->shm_rmid_forced = 0;
 114         ns->shm_tot = 0;
 115         ipc_init_ids(&shm_ids(ns));
 116 }
 117
 118 /*
 119  * Called with shm_ids.rwsem (writer) and the shp structure locked.
 120  * Only shm_ids.rwsem remains locked on exit.
 121  */
 122 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 123 {
 124         struct shmid_kernel *shp;
 125
 126         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 127         WARN_ON(ns != shp->ns);
 128
 129         if (shp->shm_nattch) {
 130                 shp->shm_perm.mode |= SHM_DEST;
 131                 /* Do not find it any more */
 132                 ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
 133                 shm_unlock(shp);
 134         } else
 135                 shm_destroy(ns, shp);
 136 }
 137
 138 #ifdef CONFIG_IPC_NS
 139 void shm_exit_ns(struct ipc_namespace *ns)
 140 {
 141         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 142         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 143         rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
 144 }
 145 #endif
 146
 147 static int __init ipc_ns_init(void)
 148 {
 149         shm_init_ns(&init_ipc_ns);
 150         return 0;
 151 }
 152
 153 pure_initcall(ipc_ns_init);
 154
 155 void __init shm_init(void)
 156 {
 157         ipc_init_proc_interface("sysvipc/shm",
 158 #if BITS_PER_LONG <= 32
 159                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 160 #else
 161                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 162 #endif
 163                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 164 }
 165
 166 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 167 {
 168         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&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 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 177 {
 178         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 179
 180         if (IS_ERR(ipcp))
 181                 return ERR_CAST(ipcp);
 182
 183         return container_of(ipcp, struct shmid_kernel, shm_perm);
 184 }
 185
 186 /*
 187  * shm_lock_(check_) routines are called in the paths where the rwsem
 188  * is not necessarily held.
 189  */
 190 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 191 {
 192         struct kern_ipc_perm *ipcp;
 193
 194         rcu_read_lock();
 195         ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 196         if (IS_ERR(ipcp))
 197                 goto err;
 198
 199         ipc_lock_object(ipcp);
 200         /*
 201          * ipc_rmid() may have already freed the ID while ipc_lock_object()
 202          * was spinning: here verify that the structure is still valid.
 203          * Upon races with RMID, return -EIDRM, thus indicating that
 204          * the ID points to a removed identifier.
 205          */
 206         if (ipc_valid_object(ipcp)) {
 207                 /* return a locked ipc object upon success */
 208                 return container_of(ipcp, struct shmid_kernel, shm_perm);
 209         }
 210
 211         ipc_unlock_object(ipcp);
 212         ipcp = ERR_PTR(-EIDRM);
 213 err:
 214         rcu_read_unlock();
 215         /*
 216          * Callers of shm_lock() must validate the status of the returned ipc
 217          * object pointer and error out as appropriate.
 218          */
 219         return ERR_CAST(ipcp);
 220 }
 221
 222 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 223 {
 224         rcu_read_lock();
 225         ipc_lock_object(&ipcp->shm_perm);
 226 }
 227
 228 static void shm_rcu_free(struct rcu_head *head)
 229 {
 230         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
 231                                                         rcu);
 232         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
 233                                                         shm_perm);
 234         security_shm_free(&shp->shm_perm);
 235         kfree(shp);
 236 }
 237
 238 /*
 239  * It has to be called with shp locked.
 240  * It must be called before ipc_rmid()
 241  */
 242 static inline void shm_clist_rm(struct shmid_kernel *shp)
 243 {
 244         struct task_struct *creator;
 245
 246         /* ensure that shm_creator does not disappear */
 247         rcu_read_lock();
 248
 249         /*
 250          * A concurrent exit_shm may do a list_del_init() as well.
 251          * Just do nothing if exit_shm already did the work
 252          */
 253         if (!list_empty(&shp->shm_clist)) {
 254                 /*
 255                  * shp->shm_creator is guaranteed to be valid *only*
 256                  * if shp->shm_clist is not empty.
 257                  */
 258                 creator = shp->shm_creator;
 259
 260                 task_lock(creator);
 261                 /*
 262                  * list_del_init() is a nop if the entry was already removed
 263                  * from the list.
 264                  */
 265                 list_del_init(&shp->shm_clist);
 266                 task_unlock(creator);
 267         }
 268         rcu_read_unlock();
 269 }
 270
 271 static inline void shm_rmid(struct shmid_kernel *s)
 272 {
 273         shm_clist_rm(s);
 274         ipc_rmid(&shm_ids(s->ns), &s->shm_perm);
 275 }
 276
 277
 278 static int __shm_open(struct shm_file_data *sfd)
 279 {
 280         struct shmid_kernel *shp;
 281
 282         shp = shm_lock(sfd->ns, sfd->id);
 283
 284         if (IS_ERR(shp))
 285                 return PTR_ERR(shp);
 286
 287         if (shp->shm_file != sfd->file) {
 288                 /* ID was reused */
 289                 shm_unlock(shp);
 290                 return -EINVAL;
 291         }
 292
 293         shp->shm_atim = ktime_get_real_seconds();
 294         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 295         shp->shm_nattch++;
 296         shm_unlock(shp);
 297         return 0;
 298 }
 299
 300 /* This is called by fork, once for every shm attach. */
 301 static void shm_open(struct vm_area_struct *vma)
 302 {
 303         struct file *file = vma->vm_file;
 304         struct shm_file_data *sfd = shm_file_data(file);
 305         int err;
 306
 307         /* Always call underlying open if present */
 308         if (sfd->vm_ops->open)
 309                 sfd->vm_ops->open(vma);
 310
 311         err = __shm_open(sfd);
 312         /*
 313          * We raced in the idr lookup or with shm_destroy().
 314          * Either way, the ID is busted.
 315          */
 316         WARN_ON_ONCE(err);
 317 }
 318
 319 /*
 320  * shm_destroy - free the struct shmid_kernel
 321  *
 322  * @ns: namespace
 323  * @shp: struct to free
 324  *
 325  * It has to be called with shp and shm_ids.rwsem (writer) locked,
 326  * but returns with shp unlocked and freed.
 327  */
 328 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 329 {
 330         struct file *shm_file;
 331
 332         shm_file = shp->shm_file;
 333         shp->shm_file = NULL;
 334         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 335         shm_rmid(shp);
 336         shm_unlock(shp);
 337         if (!is_file_hugepages(shm_file))
 338                 shmem_lock(shm_file, 0, shp->mlock_ucounts);
 339         fput(shm_file);
 340         ipc_update_pid(&shp->shm_cprid, NULL);
 341         ipc_update_pid(&shp->shm_lprid, NULL);
 342         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 343 }
 344
 345 /*
 346  * shm_may_destroy - identifies whether shm segment should be destroyed now
 347  *
 348  * Returns true if and only if there are no active users of the segment and
 349  * one of the following is true:
 350  *
 351  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 352  *
 353  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 354  */
 355 static bool shm_may_destroy(struct shmid_kernel *shp)
 356 {
 357         return (shp->shm_nattch == 0) &&
 358                (shp->ns->shm_rmid_forced ||
 359                 (shp->shm_perm.mode & SHM_DEST));
 360 }
 361
 362 /*
 363  * remove the attach descriptor vma.
 364  * free memory for segment if it is marked destroyed.
 365  * The descriptor has already been removed from the current->mm->mmap list
 366  * and will later be kfree()d.
 367  */
 368 static void __shm_close(struct shm_file_data *sfd)
 369 {
 370         struct shmid_kernel *shp;
 371         struct ipc_namespace *ns = sfd->ns;
 372
 373         down_write(&shm_ids(ns).rwsem);
 374         /* remove from the list of attaches of the shm segment */
 375         shp = shm_lock(ns, sfd->id);
 376
 377         /*
 378          * We raced in the idr lookup or with shm_destroy().
 379          * Either way, the ID is busted.
 380          */
 381         if (WARN_ON_ONCE(IS_ERR(shp)))
 382                 goto done; /* no-op */
 383
 384         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 385         shp->shm_dtim = ktime_get_real_seconds();
 386         shp->shm_nattch--;
 387         if (shm_may_destroy(shp))
 388                 shm_destroy(ns, shp);
 389         else
 390                 shm_unlock(shp);
 391 done:
 392         up_write(&shm_ids(ns).rwsem);
 393 }
 394
 395 static void shm_close(struct vm_area_struct *vma)
 396 {
 397         struct file *file = vma->vm_file;
 398         struct shm_file_data *sfd = shm_file_data(file);
 399
 400         /* Always call underlying close if present */
 401         if (sfd->vm_ops->close)
 402                 sfd->vm_ops->close(vma);
 403
 404         __shm_close(sfd);
 405 }
 406
 407 /* Called with ns->shm_ids(ns).rwsem locked */
 408 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 409 {
 410         struct ipc_namespace *ns = data;
 411         struct kern_ipc_perm *ipcp = p;
 412         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 413
 414         /*
 415          * We want to destroy segments without users and with already
 416          * exit'ed originating process.
 417          *
 418          * As shp->* are changed under rwsem, it's safe to skip shp locking.
 419          */
 420         if (!list_empty(&shp->shm_clist))
 421                 return 0;
 422
 423         if (shm_may_destroy(shp)) {
 424                 shm_lock_by_ptr(shp);
 425                 shm_destroy(ns, shp);
 426         }
 427         return 0;
 428 }
 429
 430 void shm_destroy_orphaned(struct ipc_namespace *ns)
 431 {
 432         down_write(&shm_ids(ns).rwsem);
 433         if (shm_ids(ns).in_use)
 434                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 435         up_write(&shm_ids(ns).rwsem);
 436 }
 437
 438 /* Locking assumes this will only be called with task == current */
 439 void exit_shm(struct task_struct *task)
 440 {
 441         for (;;) {
 442                 struct shmid_kernel *shp;
 443                 struct ipc_namespace *ns;
 444
 445                 task_lock(task);
 446
 447                 if (list_empty(&task->sysvshm.shm_clist)) {
 448                         task_unlock(task);
 449                         break;
 450                 }
 451
 452                 shp = list_first_entry(&task->sysvshm.shm_clist, struct shmid_kernel,
 453                                 shm_clist);
 454
 455                 /*
 456                  * 1) Get pointer to the ipc namespace. It is worth to say
 457                  * that this pointer is guaranteed to be valid because
 458                  * shp lifetime is always shorter than namespace lifetime
 459                  * in which shp lives.
 460                  * We taken task_lock it means that shp won't be freed.
 461                  */
 462                 ns = shp->ns;
 463
 464                 /*
 465                  * 2) If kernel.shm_rmid_forced is not set then only keep track of
 466                  * which shmids are orphaned, so that a later set of the sysctl
 467                  * can clean them up.
 468                  */
 469                 if (!ns->shm_rmid_forced)
 470                         goto unlink_continue;
 471
 472                 /*
 473                  * 3) get a reference to the namespace.
 474                  *    The refcount could be already 0. If it is 0, then
 475                  *    the shm objects will be free by free_ipc_work().
 476                  */
 477                 ns = get_ipc_ns_not_zero(ns);
 478                 if (!ns) {
 479 unlink_continue:
 480                         list_del_init(&shp->shm_clist);
 481                         task_unlock(task);
 482                         continue;
 483                 }
 484
 485                 /*
 486                  * 4) get a reference to shp.
 487                  *   This cannot fail: shm_clist_rm() is called before
 488                  *   ipc_rmid(), thus the refcount cannot be 0.
 489                  */
 490                 WARN_ON(!ipc_rcu_getref(&shp->shm_perm));
 491
 492                 /*
 493                  * 5) unlink the shm segment from the list of segments
 494                  *    created by current.
 495                  *    This must be done last. After unlinking,
 496                  *    only the refcounts obtained above prevent IPC_RMID
 497                  *    from destroying the segment or the namespace.
 498                  */
 499                 list_del_init(&shp->shm_clist);
 500
 501                 task_unlock(task);
 502
 503                 /*
 504                  * 6) we have all references
 505                  *    Thus lock & if needed destroy shp.
 506                  */
 507                 down_write(&shm_ids(ns).rwsem);
 508                 shm_lock_by_ptr(shp);
 509                 /*
 510                  * rcu_read_lock was implicitly taken in shm_lock_by_ptr, it's
 511                  * safe to call ipc_rcu_putref here
 512                  */
 513                 ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 514
 515                 if (ipc_valid_object(&shp->shm_perm)) {
 516                         if (shm_may_destroy(shp))
 517                                 shm_destroy(ns, shp);
 518                         else
 519                                 shm_unlock(shp);
 520                 } else {
 521                         /*
 522                          * Someone else deleted the shp from namespace
 523                          * idr/kht while we have waited.
 524                          * Just unlock and continue.
 525                          */
 526                         shm_unlock(shp);
 527                 }
 528
 529                 up_write(&shm_ids(ns).rwsem);
 530                 put_ipc_ns(ns); /* paired with get_ipc_ns_not_zero */
 531         }
 532 }
 533
 534 static vm_fault_t shm_fault(struct vm_fault *vmf)
 535 {
 536         struct file *file = vmf->vma->vm_file;
 537         struct shm_file_data *sfd = shm_file_data(file);
 538
 539         return sfd->vm_ops->fault(vmf);
 540 }
 541
 542 static int shm_may_split(struct vm_area_struct *vma, unsigned long addr)
 543 {
 544         struct file *file = vma->vm_file;
 545         struct shm_file_data *sfd = shm_file_data(file);
 546
 547         if (sfd->vm_ops->may_split)
 548                 return sfd->vm_ops->may_split(vma, addr);
 549
 550         return 0;
 551 }
 552
 553 static unsigned long shm_pagesize(struct vm_area_struct *vma)
 554 {
 555         struct file *file = vma->vm_file;
 556         struct shm_file_data *sfd = shm_file_data(file);
 557
 558         if (sfd->vm_ops->pagesize)
 559                 return sfd->vm_ops->pagesize(vma);
 560
 561         return PAGE_SIZE;
 562 }
 563
 564 #ifdef CONFIG_NUMA
 565 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 566 {
 567         struct file *file = vma->vm_file;
 568         struct shm_file_data *sfd = shm_file_data(file);
 569         int err = 0;
 570
 571         if (sfd->vm_ops->set_policy)
 572                 err = sfd->vm_ops->set_policy(vma, new);
 573         return err;
 574 }
 575
 576 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 577                                         unsigned long addr)
 578 {
 579         struct file *file = vma->vm_file;
 580         struct shm_file_data *sfd = shm_file_data(file);
 581         struct mempolicy *pol = NULL;
 582
 583         if (sfd->vm_ops->get_policy)
 584                 pol = sfd->vm_ops->get_policy(vma, addr);
 585         else if (vma->vm_policy)
 586                 pol = vma->vm_policy;
 587
 588         return pol;
 589 }
 590 #endif
 591
 592 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 593 {
 594         struct shm_file_data *sfd = shm_file_data(file);
 595         int ret;
 596
 597         /*
 598          * In case of remap_file_pages() emulation, the file can represent an
 599          * IPC ID that was removed, and possibly even reused by another shm
 600          * segment already.  Propagate this case as an error to caller.
 601          */
 602         ret = __shm_open(sfd);
 603         if (ret)
 604                 return ret;
 605
 606         ret = call_mmap(sfd->file, vma);
 607         if (ret) {
 608                 __shm_close(sfd);
 609                 return ret;
 610         }
 611         sfd->vm_ops = vma->vm_ops;
 612 #ifdef CONFIG_MMU
 613         WARN_ON(!sfd->vm_ops->fault);
 614 #endif
 615         vma->vm_ops = &shm_vm_ops;
 616         return 0;
 617 }
 618
 619 static int shm_release(struct inode *ino, struct file *file)
 620 {
 621         struct shm_file_data *sfd = shm_file_data(file);
 622
 623         put_ipc_ns(sfd->ns);
 624         fput(sfd->file);
 625         shm_file_data(file) = NULL;
 626         kfree(sfd);
 627         return 0;
 628 }
 629
 630 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 631 {
 632         struct shm_file_data *sfd = shm_file_data(file);
 633
 634         if (!sfd->file->f_op->fsync)
 635                 return -EINVAL;
 636         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 637 }
 638
 639 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 640                           loff_t len)
 641 {
 642         struct shm_file_data *sfd = shm_file_data(file);
 643
 644         if (!sfd->file->f_op->fallocate)
 645                 return -EOPNOTSUPP;
 646         return sfd->file->f_op->fallocate(file, mode, offset, len);
 647 }
 648
 649 static unsigned long shm_get_unmapped_area(struct file *file,
 650         unsigned long addr, unsigned long len, unsigned long pgoff,
 651         unsigned long flags)
 652 {
 653         struct shm_file_data *sfd = shm_file_data(file);
 654
 655         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 656                                                 pgoff, flags);
 657 }
 658
 659 static const struct file_operations shm_file_operations = {
 660         .mmap           = shm_mmap,
 661         .fsync          = shm_fsync,
 662         .release        = shm_release,
 663         .get_unmapped_area      = shm_get_unmapped_area,
 664         .llseek         = noop_llseek,
 665         .fallocate      = shm_fallocate,
 666 };
 667
 668 /*
 669  * shm_file_operations_huge is now identical to shm_file_operations,
 670  * but we keep it distinct for the sake of is_file_shm_hugepages().
 671  */
 672 static const struct file_operations shm_file_operations_huge = {
 673         .mmap           = shm_mmap,
 674         .fsync          = shm_fsync,
 675         .release        = shm_release,
 676         .get_unmapped_area      = shm_get_unmapped_area,
 677         .llseek         = noop_llseek,
 678         .fallocate      = shm_fallocate,
 679 };
 680
 681 bool is_file_shm_hugepages(struct file *file)
 682 {
 683         return file->f_op == &shm_file_operations_huge;
 684 }
 685
 686 static const struct vm_operations_struct shm_vm_ops = {
 687         .open   = shm_open,     /* callback for a new vm-area open */
 688         .close  = shm_close,    /* callback for when the vm-area is released */
 689         .fault  = shm_fault,
 690         .may_split = shm_may_split,
 691         .pagesize = shm_pagesize,
 692 #if defined(CONFIG_NUMA)
 693         .set_policy = shm_set_policy,
 694         .get_policy = shm_get_policy,
 695 #endif
 696 };
 697
 698 /**
 699  * newseg - Create a new shared memory segment
 700  * @ns: namespace
 701  * @params: ptr to the structure that contains key, size and shmflg
 702  *
 703  * Called with shm_ids.rwsem held as a writer.
 704  */
 705 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 706 {
 707         key_t key = params->key;
 708         int shmflg = params->flg;
 709         size_t size = params->u.size;
 710         int error;
 711         struct shmid_kernel *shp;
 712         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 713         struct file *file;
 714         char name[13];
 715         vm_flags_t acctflag = 0;
 716
 717         if (size < SHMMIN || size > ns->shm_ctlmax)
 718                 return -EINVAL;
 719
 720         if (numpages << PAGE_SHIFT < size)
 721                 return -ENOSPC;
 722
 723         if (ns->shm_tot + numpages < ns->shm_tot ||
 724                         ns->shm_tot + numpages > ns->shm_ctlall)
 725                 return -ENOSPC;
 726
 727         shp = kmalloc(sizeof(*shp), GFP_KERNEL_ACCOUNT);
 728         if (unlikely(!shp))
 729                 return -ENOMEM;
 730
 731         shp->shm_perm.key = key;
 732         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 733         shp->mlock_ucounts = NULL;
 734
 735         shp->shm_perm.security = NULL;
 736         error = security_shm_alloc(&shp->shm_perm);
 737         if (error) {
 738                 kfree(shp);
 739                 return error;
 740         }
 741
 742         sprintf(name, "SYSV%08x", key);
 743         if (shmflg & SHM_HUGETLB) {
 744                 struct hstate *hs;
 745                 size_t hugesize;
 746
 747                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 748                 if (!hs) {
 749                         error = -EINVAL;
 750                         goto no_file;
 751                 }
 752                 hugesize = ALIGN(size, huge_page_size(hs));
 753
 754                 /* hugetlb_file_setup applies strict accounting */
 755                 if (shmflg & SHM_NORESERVE)
 756                         acctflag = VM_NORESERVE;
 757                 file = hugetlb_file_setup(name, hugesize, acctflag,
 758                                 HUGETLB_SHMFS_INODE, (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 759         } else {
 760                 /*
 761                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 762                  * if it's asked for.
 763                  */
 764                 if  ((shmflg & SHM_NORESERVE) &&
 765                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 766                         acctflag = VM_NORESERVE;
 767                 file = shmem_kernel_file_setup(name, size, acctflag);
 768         }
 769         error = PTR_ERR(file);
 770         if (IS_ERR(file))
 771                 goto no_file;
 772
 773         shp->shm_cprid = get_pid(task_tgid(current));
 774         shp->shm_lprid = NULL;
 775         shp->shm_atim = shp->shm_dtim = 0;
 776         shp->shm_ctim = ktime_get_real_seconds();
 777         shp->shm_segsz = size;
 778         shp->shm_nattch = 0;
 779         shp->shm_file = file;
 780         shp->shm_creator = current;
 781
 782         /* ipc_addid() locks shp upon success. */
 783         error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 784         if (error < 0)
 785                 goto no_id;
 786
 787         shp->ns = ns;
 788
 789         task_lock(current);
 790         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 791         task_unlock(current);
 792
 793         /*
 794          * shmid gets reported as "inode#" in /proc/pid/maps.
 795          * proc-ps tools use this. Changing this will break them.
 796          */
 797         file_inode(file)->i_ino = shp->shm_perm.id;
 798
 799         ns->shm_tot += numpages;
 800         error = shp->shm_perm.id;
 801
 802         ipc_unlock_object(&shp->shm_perm);
 803         rcu_read_unlock();
 804         return error;
 805
 806 no_id:
 807         ipc_update_pid(&shp->shm_cprid, NULL);
 808         ipc_update_pid(&shp->shm_lprid, NULL);
 809         fput(file);
 810         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 811         return error;
 812 no_file:
 813         call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
 814         return error;
 815 }
 816
 817 /*
 818  * Called with shm_ids.rwsem and ipcp locked.
 819  */
 820 static int shm_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params)
 821 {
 822         struct shmid_kernel *shp;
 823
 824         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 825         if (shp->shm_segsz < params->u.size)
 826                 return -EINVAL;
 827
 828         return 0;
 829 }
 830
 831 long ksys_shmget(key_t key, size_t size, int shmflg)
 832 {
 833         struct ipc_namespace *ns;
 834         static const struct ipc_ops shm_ops = {
 835                 .getnew = newseg,
 836                 .associate = security_shm_associate,
 837                 .more_checks = shm_more_checks,
 838         };
 839         struct ipc_params shm_params;
 840
 841         ns = current->nsproxy->ipc_ns;
 842
 843         shm_params.key = key;
 844         shm_params.flg = shmflg;
 845         shm_params.u.size = size;
 846
 847         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 848 }
 849
 850 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 851 {
 852         return ksys_shmget(key, size, shmflg);
 853 }
 854
 855 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 856 {
 857         switch (version) {
 858         case IPC_64:
 859                 return copy_to_user(buf, in, sizeof(*in));
 860         case IPC_OLD:
 861             {
 862                 struct shmid_ds out;
 863
 864                 memset(&out, 0, sizeof(out));
 865                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 866                 out.shm_segsz   = in->shm_segsz;
 867                 out.shm_atime   = in->shm_atime;
 868                 out.shm_dtime   = in->shm_dtime;
 869                 out.shm_ctime   = in->shm_ctime;
 870                 out.shm_cpid    = in->shm_cpid;
 871                 out.shm_lpid    = in->shm_lpid;
 872                 out.shm_nattch  = in->shm_nattch;
 873
 874                 return copy_to_user(buf, &out, sizeof(out));
 875             }
 876         default:
 877                 return -EINVAL;
 878         }
 879 }
 880
 881 static inline unsigned long
 882 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 883 {
 884         switch (version) {
 885         case IPC_64:
 886                 if (copy_from_user(out, buf, sizeof(*out)))
 887                         return -EFAULT;
 888                 return 0;
 889         case IPC_OLD:
 890             {
 891                 struct shmid_ds tbuf_old;
 892
 893                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 894                         return -EFAULT;
 895
 896                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 897                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 898                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 899
 900                 return 0;
 901             }
 902         default:
 903                 return -EINVAL;
 904         }
 905 }
 906
 907 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 908 {
 909         switch (version) {
 910         case IPC_64:
 911                 return copy_to_user(buf, in, sizeof(*in));
 912         case IPC_OLD:
 913             {
 914                 struct shminfo out;
 915
 916                 if (in->shmmax > INT_MAX)
 917                         out.shmmax = INT_MAX;
 918                 else
 919                         out.shmmax = (int)in->shmmax;
 920
 921                 out.shmmin      = in->shmmin;
 922                 out.shmmni      = in->shmmni;
 923                 out.shmseg      = in->shmseg;
 924                 out.shmall      = in->shmall;
 925
 926                 return copy_to_user(buf, &out, sizeof(out));
 927             }
 928         default:
 929                 return -EINVAL;
 930         }
 931 }
 932
 933 /*
 934  * Calculate and add used RSS and swap pages of a shm.
 935  * Called with shm_ids.rwsem held as a reader
 936  */
 937 static void shm_add_rss_swap(struct shmid_kernel *shp,
 938         unsigned long *rss_add, unsigned long *swp_add)
 939 {
 940         struct inode *inode;
 941
 942         inode = file_inode(shp->shm_file);
 943
 944         if (is_file_hugepages(shp->shm_file)) {
 945                 struct address_space *mapping = inode->i_mapping;
 946                 struct hstate *h = hstate_file(shp->shm_file);
 947                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 948         } else {
 949 #ifdef CONFIG_SHMEM
 950                 struct shmem_inode_info *info = SHMEM_I(inode);
 951
 952                 spin_lock_irq(&info->lock);
 953                 *rss_add += inode->i_mapping->nrpages;
 954                 *swp_add += info->swapped;
 955                 spin_unlock_irq(&info->lock);
 956 #else
 957                 *rss_add += inode->i_mapping->nrpages;
 958 #endif
 959         }
 960 }
 961
 962 /*
 963  * Called with shm_ids.rwsem held as a reader
 964  */
 965 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 966                 unsigned long *swp)
 967 {
 968         int next_id;
 969         int total, in_use;
 970
 971         *rss = 0;
 972         *swp = 0;
 973
 974         in_use = shm_ids(ns).in_use;
 975
 976         for (total = 0, next_id = 0; total < in_use; next_id++) {
 977                 struct kern_ipc_perm *ipc;
 978                 struct shmid_kernel *shp;
 979
 980                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 981                 if (ipc == NULL)
 982                         continue;
 983                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 984
 985                 shm_add_rss_swap(shp, rss, swp);
 986
 987                 total++;
 988         }
 989 }
 990
 991 /*
 992  * This function handles some shmctl commands which require the rwsem
 993  * to be held in write mode.
 994  * NOTE: no locks must be held, the rwsem is taken inside this function.
 995  */
 996 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 997                        struct shmid64_ds *shmid64)
 998 {
 999         struct kern_ipc_perm *ipcp;
1000         struct shmid_kernel *shp;
1001         int err;
1002
1003         down_write(&shm_ids(ns).rwsem);
1004         rcu_read_lock();
1005
1006         ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
1007                                       &shmid64->shm_perm, 0);
1008         if (IS_ERR(ipcp)) {
1009                 err = PTR_ERR(ipcp);
1010                 goto out_unlock1;
1011         }
1012
1013         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1014
1015         err = security_shm_shmctl(&shp->shm_perm, cmd);
1016         if (err)
1017                 goto out_unlock1;
1018
1019         switch (cmd) {
1020         case IPC_RMID:
1021                 ipc_lock_object(&shp->shm_perm);
1022                 /* do_shm_rmid unlocks the ipc object and rcu */
1023                 do_shm_rmid(ns, ipcp);
1024                 goto out_up;
1025         case IPC_SET:
1026                 ipc_lock_object(&shp->shm_perm);
1027                 err = ipc_update_perm(&shmid64->shm_perm, ipcp);
1028                 if (err)
1029                         goto out_unlock0;
1030                 shp->shm_ctim = ktime_get_real_seconds();
1031                 break;
1032         default:
1033                 err = -EINVAL;
1034                 goto out_unlock1;
1035         }
1036
1037 out_unlock0:
1038         ipc_unlock_object(&shp->shm_perm);
1039 out_unlock1:
1040         rcu_read_unlock();
1041 out_up:
1042         up_write(&shm_ids(ns).rwsem);
1043         return err;
1044 }
1045
1046 static int shmctl_ipc_info(struct ipc_namespace *ns,
1047                            struct shminfo64 *shminfo)
1048 {
1049         int err = security_shm_shmctl(NULL, IPC_INFO);
1050         if (!err) {
1051                 memset(shminfo, 0, sizeof(*shminfo));
1052                 shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
1053                 shminfo->shmmax = ns->shm_ctlmax;
1054                 shminfo->shmall = ns->shm_ctlall;
1055                 shminfo->shmmin = SHMMIN;
1056                 down_read(&shm_ids(ns).rwsem);
1057                 err = ipc_get_maxidx(&shm_ids(ns));
1058                 up_read(&shm_ids(ns).rwsem);
1059                 if (err < 0)
1060                         err = 0;
1061         }
1062         return err;
1063 }
1064
1065 static int shmctl_shm_info(struct ipc_namespace *ns,
1066                            struct shm_info *shm_info)
1067 {
1068         int err = security_shm_shmctl(NULL, SHM_INFO);
1069         if (!err) {
1070                 memset(shm_info, 0, sizeof(*shm_info));
1071                 down_read(&shm_ids(ns).rwsem);
1072                 shm_info->used_ids = shm_ids(ns).in_use;
1073                 shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
1074                 shm_info->shm_tot = ns->shm_tot;
1075                 shm_info->swap_attempts = 0;
1076                 shm_info->swap_successes = 0;
1077                 err = ipc_get_maxidx(&shm_ids(ns));
1078                 up_read(&shm_ids(ns).rwsem);
1079                 if (err < 0)
1080                         err = 0;
1081         }
1082         return err;
1083 }
1084
1085 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
1086                         int cmd, struct shmid64_ds *tbuf)
1087 {
1088         struct shmid_kernel *shp;
1089         int err;
1090
1091         memset(tbuf, 0, sizeof(*tbuf));
1092
1093         rcu_read_lock();
1094         if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
1095                 shp = shm_obtain_object(ns, shmid);
1096                 if (IS_ERR(shp)) {
1097                         err = PTR_ERR(shp);
1098                         goto out_unlock;
1099                 }
1100         } else { /* IPC_STAT */
1101                 shp = shm_obtain_object_check(ns, shmid);
1102                 if (IS_ERR(shp)) {
1103                         err = PTR_ERR(shp);
1104                         goto out_unlock;
1105                 }
1106         }
1107
1108         /*
1109          * Semantically SHM_STAT_ANY ought to be identical to
1110          * that functionality provided by the /proc/sysvipc/
1111          * interface. As such, only audit these calls and
1112          * do not do traditional S_IRUGO permission checks on
1113          * the ipc object.
1114          */
1115         if (cmd == SHM_STAT_ANY)
1116                 audit_ipc_obj(&shp->shm_perm);
1117         else {
1118                 err = -EACCES;
1119                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
1120                         goto out_unlock;
1121         }
1122
1123         err = security_shm_shmctl(&shp->shm_perm, cmd);
1124         if (err)
1125                 goto out_unlock;
1126
1127         ipc_lock_object(&shp->shm_perm);
1128
1129         if (!ipc_valid_object(&shp->shm_perm)) {
1130                 ipc_unlock_object(&shp->shm_perm);
1131                 err = -EIDRM;
1132                 goto out_unlock;
1133         }
1134
1135         kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1136         tbuf->shm_segsz = shp->shm_segsz;
1137         tbuf->shm_atime = shp->shm_atim;
1138         tbuf->shm_dtime = shp->shm_dtim;
1139         tbuf->shm_ctime = shp->shm_ctim;
1140 #ifndef CONFIG_64BIT
1141         tbuf->shm_atime_high = shp->shm_atim >> 32;
1142         tbuf->shm_dtime_high = shp->shm_dtim >> 32;
1143         tbuf->shm_ctime_high = shp->shm_ctim >> 32;
1144 #endif
1145         tbuf->shm_cpid  = pid_vnr(shp->shm_cprid);
1146         tbuf->shm_lpid  = pid_vnr(shp->shm_lprid);
1147         tbuf->shm_nattch = shp->shm_nattch;
1148
1149         if (cmd == IPC_STAT) {
1150                 /*
1151                  * As defined in SUS:
1152                  * Return 0 on success
1153                  */
1154                 err = 0;
1155         } else {
1156                 /*
1157                  * SHM_STAT and SHM_STAT_ANY (both Linux specific)
1158                  * Return the full id, including the sequence number
1159                  */
1160                 err = shp->shm_perm.id;
1161         }
1162
1163         ipc_unlock_object(&shp->shm_perm);
1164 out_unlock:
1165         rcu_read_unlock();
1166         return err;
1167 }
1168
1169 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1170 {
1171         struct shmid_kernel *shp;
1172         struct file *shm_file;
1173         int err;
1174
1175         rcu_read_lock();
1176         shp = shm_obtain_object_check(ns, shmid);
1177         if (IS_ERR(shp)) {
1178                 err = PTR_ERR(shp);
1179                 goto out_unlock1;
1180         }
1181
1182         audit_ipc_obj(&(shp->shm_perm));
1183         err = security_shm_shmctl(&shp->shm_perm, cmd);
1184         if (err)
1185                 goto out_unlock1;
1186
1187         ipc_lock_object(&shp->shm_perm);
1188
1189         /* check if shm_destroy() is tearing down shp */
1190         if (!ipc_valid_object(&shp->shm_perm)) {
1191                 err = -EIDRM;
1192                 goto out_unlock0;
1193         }
1194
1195         if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1196                 kuid_t euid = current_euid();
1197
1198                 if (!uid_eq(euid, shp->shm_perm.uid) &&
1199                     !uid_eq(euid, shp->shm_perm.cuid)) {
1200                         err = -EPERM;
1201                         goto out_unlock0;
1202                 }
1203                 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1204                         err = -EPERM;
1205                         goto out_unlock0;
1206                 }
1207         }
1208
1209         shm_file = shp->shm_file;
1210         if (is_file_hugepages(shm_file))
1211                 goto out_unlock0;
1212
1213         if (cmd == SHM_LOCK) {
1214                 struct ucounts *ucounts = current_ucounts();
1215
1216                 err = shmem_lock(shm_file, 1, ucounts);
1217                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1218                         shp->shm_perm.mode |= SHM_LOCKED;
1219                         shp->mlock_ucounts = ucounts;
1220                 }
1221                 goto out_unlock0;
1222         }
1223
1224         /* SHM_UNLOCK */
1225         if (!(shp->shm_perm.mode & SHM_LOCKED))
1226                 goto out_unlock0;
1227         shmem_lock(shm_file, 0, shp->mlock_ucounts);
1228         shp->shm_perm.mode &= ~SHM_LOCKED;
1229         shp->mlock_ucounts = NULL;
1230         get_file(shm_file);
1231         ipc_unlock_object(&shp->shm_perm);
1232         rcu_read_unlock();
1233         shmem_unlock_mapping(shm_file->f_mapping);
1234
1235         fput(shm_file);
1236         return err;
1237
1238 out_unlock0:
1239         ipc_unlock_object(&shp->shm_perm);
1240 out_unlock1:
1241         rcu_read_unlock();
1242         return err;
1243 }
1244
1245 static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
1246 {
1247         int err;
1248         struct ipc_namespace *ns;
1249         struct shmid64_ds sem64;
1250
1251         if (cmd < 0 || shmid < 0)
1252                 return -EINVAL;
1253
1254         ns = current->nsproxy->ipc_ns;
1255
1256         switch (cmd) {
1257         case IPC_INFO: {
1258                 struct shminfo64 shminfo;
1259                 err = shmctl_ipc_info(ns, &shminfo);
1260                 if (err < 0)
1261                         return err;
1262                 if (copy_shminfo_to_user(buf, &shminfo, version))
1263                         err = -EFAULT;
1264                 return err;
1265         }
1266         case SHM_INFO: {
1267                 struct shm_info shm_info;
1268                 err = shmctl_shm_info(ns, &shm_info);
1269                 if (err < 0)
1270                         return err;
1271                 if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1272                         err = -EFAULT;
1273                 return err;
1274         }
1275         case SHM_STAT:
1276         case SHM_STAT_ANY:
1277         case IPC_STAT: {
1278                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1279                 if (err < 0)
1280                         return err;
1281                 if (copy_shmid_to_user(buf, &sem64, version))
1282                         err = -EFAULT;
1283                 return err;
1284         }
1285         case IPC_SET:
1286                 if (copy_shmid_from_user(&sem64, buf, version))
1287                         return -EFAULT;
1288                 fallthrough;
1289         case IPC_RMID:
1290                 return shmctl_down(ns, shmid, cmd, &sem64);
1291         case SHM_LOCK:
1292         case SHM_UNLOCK:
1293                 return shmctl_do_lock(ns, shmid, cmd);
1294         default:
1295                 return -EINVAL;
1296         }
1297 }
1298
1299 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1300 {
1301         return ksys_shmctl(shmid, cmd, buf, IPC_64);
1302 }
1303
1304 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
1305 long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1306 {
1307         int version = ipc_parse_version(&cmd);
1308
1309         return ksys_shmctl(shmid, cmd, buf, version);
1310 }
1311
1312 SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1313 {
1314         return ksys_old_shmctl(shmid, cmd, buf);
1315 }
1316 #endif
1317
1318 #ifdef CONFIG_COMPAT
1319
1320 struct compat_shmid_ds {
1321         struct compat_ipc_perm shm_perm;
1322         int shm_segsz;
1323         old_time32_t shm_atime;
1324         old_time32_t shm_dtime;
1325         old_time32_t shm_ctime;
1326         compat_ipc_pid_t shm_cpid;
1327         compat_ipc_pid_t shm_lpid;
1328         unsigned short shm_nattch;
1329         unsigned short shm_unused;
1330         compat_uptr_t shm_unused2;
1331         compat_uptr_t shm_unused3;
1332 };
1333
1334 struct compat_shminfo64 {
1335         compat_ulong_t shmmax;
1336         compat_ulong_t shmmin;
1337         compat_ulong_t shmmni;
1338         compat_ulong_t shmseg;
1339         compat_ulong_t shmall;
1340         compat_ulong_t __unused1;
1341         compat_ulong_t __unused2;
1342         compat_ulong_t __unused3;
1343         compat_ulong_t __unused4;
1344 };
1345
1346 struct compat_shm_info {
1347         compat_int_t used_ids;
1348         compat_ulong_t shm_tot, shm_rss, shm_swp;
1349         compat_ulong_t swap_attempts, swap_successes;
1350 };
1351
1352 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1353                                         int version)
1354 {
1355         if (in->shmmax > INT_MAX)
1356                 in->shmmax = INT_MAX;
1357         if (version == IPC_64) {
1358                 struct compat_shminfo64 info;
1359                 memset(&info, 0, sizeof(info));
1360                 info.shmmax = in->shmmax;
1361                 info.shmmin = in->shmmin;
1362                 info.shmmni = in->shmmni;
1363                 info.shmseg = in->shmseg;
1364                 info.shmall = in->shmall;
1365                 return copy_to_user(buf, &info, sizeof(info));
1366         } else {
1367                 struct shminfo info;
1368                 memset(&info, 0, sizeof(info));
1369                 info.shmmax = in->shmmax;
1370                 info.shmmin = in->shmmin;
1371                 info.shmmni = in->shmmni;
1372                 info.shmseg = in->shmseg;
1373                 info.shmall = in->shmall;
1374                 return copy_to_user(buf, &info, sizeof(info));
1375         }
1376 }
1377
1378 static int put_compat_shm_info(struct shm_info *ip,
1379                                 struct compat_shm_info __user *uip)
1380 {
1381         struct compat_shm_info info;
1382
1383         memset(&info, 0, sizeof(info));
1384         info.used_ids = ip->used_ids;
1385         info.shm_tot = ip->shm_tot;
1386         info.shm_rss = ip->shm_rss;
1387         info.shm_swp = ip->shm_swp;
1388         info.swap_attempts = ip->swap_attempts;
1389         info.swap_successes = ip->swap_successes;
1390         return copy_to_user(uip, &info, sizeof(info));
1391 }
1392
1393 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1394                                         int version)
1395 {
1396         if (version == IPC_64) {
1397                 struct compat_shmid64_ds v;
1398                 memset(&v, 0, sizeof(v));
1399                 to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1400                 v.shm_atime      = lower_32_bits(in->shm_atime);
1401                 v.shm_atime_high = upper_32_bits(in->shm_atime);
1402                 v.shm_dtime      = lower_32_bits(in->shm_dtime);
1403                 v.shm_dtime_high = upper_32_bits(in->shm_dtime);
1404                 v.shm_ctime      = lower_32_bits(in->shm_ctime);
1405                 v.shm_ctime_high = upper_32_bits(in->shm_ctime);
1406                 v.shm_segsz = in->shm_segsz;
1407                 v.shm_nattch = in->shm_nattch;
1408                 v.shm_cpid = in->shm_cpid;
1409                 v.shm_lpid = in->shm_lpid;
1410                 return copy_to_user(buf, &v, sizeof(v));
1411         } else {
1412                 struct compat_shmid_ds v;
1413                 memset(&v, 0, sizeof(v));
1414                 to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1415                 v.shm_perm.key = in->shm_perm.key;
1416                 v.shm_atime = in->shm_atime;
1417                 v.shm_dtime = in->shm_dtime;
1418                 v.shm_ctime = in->shm_ctime;
1419                 v.shm_segsz = in->shm_segsz;
1420                 v.shm_nattch = in->shm_nattch;
1421                 v.shm_cpid = in->shm_cpid;
1422                 v.shm_lpid = in->shm_lpid;
1423                 return copy_to_user(buf, &v, sizeof(v));
1424         }
1425 }
1426
1427 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1428                                         int version)
1429 {
1430         memset(out, 0, sizeof(*out));
1431         if (version == IPC_64) {
1432                 struct compat_shmid64_ds __user *p = buf;
1433                 return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1434         } else {
1435                 struct compat_shmid_ds __user *p = buf;
1436                 return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1437         }
1438 }
1439
1440 static long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
1441 {
1442         struct ipc_namespace *ns;
1443         struct shmid64_ds sem64;
1444         int err;
1445
1446         ns = current->nsproxy->ipc_ns;
1447
1448         if (cmd < 0 || shmid < 0)
1449                 return -EINVAL;
1450
1451         switch (cmd) {
1452         case IPC_INFO: {
1453                 struct shminfo64 shminfo;
1454                 err = shmctl_ipc_info(ns, &shminfo);
1455                 if (err < 0)
1456                         return err;
1457                 if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1458                         err = -EFAULT;
1459                 return err;
1460         }
1461         case SHM_INFO: {
1462                 struct shm_info shm_info;
1463                 err = shmctl_shm_info(ns, &shm_info);
1464                 if (err < 0)
1465                         return err;
1466                 if (put_compat_shm_info(&shm_info, uptr))
1467                         err = -EFAULT;
1468                 return err;
1469         }
1470         case IPC_STAT:
1471         case SHM_STAT_ANY:
1472         case SHM_STAT:
1473                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1474                 if (err < 0)
1475                         return err;
1476                 if (copy_compat_shmid_to_user(uptr, &sem64, version))
1477                         err = -EFAULT;
1478                 return err;
1479
1480         case IPC_SET:
1481                 if (copy_compat_shmid_from_user(&sem64, uptr, version))
1482                         return -EFAULT;
1483                 fallthrough;
1484         case IPC_RMID:
1485                 return shmctl_down(ns, shmid, cmd, &sem64);
1486         case SHM_LOCK:
1487         case SHM_UNLOCK:
1488                 return shmctl_do_lock(ns, shmid, cmd);
1489         default:
1490                 return -EINVAL;
1491         }
1492         return err;
1493 }
1494
1495 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1496 {
1497         return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
1498 }
1499
1500 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
1501 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
1502 {
1503         int version = compat_ipc_parse_version(&cmd);
1504
1505         return compat_ksys_shmctl(shmid, cmd, uptr, version);
1506 }
1507
1508 COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
1509 {
1510         return compat_ksys_old_shmctl(shmid, cmd, uptr);
1511 }
1512 #endif
1513 #endif
1514
1515 /*
1516  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1517  *
1518  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1519  * "raddr" thing points to kernel space, and there has to be a wrapper around
1520  * this.
1521  */
1522 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1523               ulong *raddr, unsigned long shmlba)
1524 {
1525         struct shmid_kernel *shp;
1526         unsigned long addr = (unsigned long)shmaddr;
1527         unsigned long size;
1528         struct file *file, *base;
1529         int    err;
1530         unsigned long flags = MAP_SHARED;
1531         unsigned long prot;
1532         int acc_mode;
1533         struct ipc_namespace *ns;
1534         struct shm_file_data *sfd;
1535         int f_flags;
1536         unsigned long populate = 0;
1537
1538         err = -EINVAL;
1539         if (shmid < 0)
1540                 goto out;
1541
1542         if (addr) {
1543                 if (addr & (shmlba - 1)) {
1544                         if (shmflg & SHM_RND) {
1545                                 addr &= ~(shmlba - 1);  /* round down */
1546
1547                                 /*
1548                                  * Ensure that the round-down is non-nil
1549                                  * when remapping. This can happen for
1550                                  * cases when addr < shmlba.
1551                                  */
1552                                 if (!addr && (shmflg & SHM_REMAP))
1553                                         goto out;
1554                         } else
1555 #ifndef __ARCH_FORCE_SHMLBA
1556                                 if (addr & ~PAGE_MASK)
1557 #endif
1558                                         goto out;
1559                 }
1560
1561                 flags |= MAP_FIXED;
1562         } else if ((shmflg & SHM_REMAP))
1563                 goto out;
1564
1565         if (shmflg & SHM_RDONLY) {
1566                 prot = PROT_READ;
1567                 acc_mode = S_IRUGO;
1568                 f_flags = O_RDONLY;
1569         } else {
1570                 prot = PROT_READ | PROT_WRITE;
1571                 acc_mode = S_IRUGO | S_IWUGO;
1572                 f_flags = O_RDWR;
1573         }
1574         if (shmflg & SHM_EXEC) {
1575                 prot |= PROT_EXEC;
1576                 acc_mode |= S_IXUGO;
1577         }
1578
1579         /*
1580          * We cannot rely on the fs check since SYSV IPC does have an
1581          * additional creator id...
1582          */
1583         ns = current->nsproxy->ipc_ns;
1584         rcu_read_lock();
1585         shp = shm_obtain_object_check(ns, shmid);
1586         if (IS_ERR(shp)) {
1587                 err = PTR_ERR(shp);
1588                 goto out_unlock;
1589         }
1590
1591         err = -EACCES;
1592         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1593                 goto out_unlock;
1594
1595         err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1596         if (err)
1597                 goto out_unlock;
1598
1599         ipc_lock_object(&shp->shm_perm);
1600
1601         /* check if shm_destroy() is tearing down shp */
1602         if (!ipc_valid_object(&shp->shm_perm)) {
1603                 ipc_unlock_object(&shp->shm_perm);
1604                 err = -EIDRM;
1605                 goto out_unlock;
1606         }
1607
1608         /*
1609          * We need to take a reference to the real shm file to prevent the
1610          * pointer from becoming stale in cases where the lifetime of the outer
1611          * file extends beyond that of the shm segment.  It's not usually
1612          * possible, but it can happen during remap_file_pages() emulation as
1613          * that unmaps the memory, then does ->mmap() via file reference only.
1614          * We'll deny the ->mmap() if the shm segment was since removed, but to
1615          * detect shm ID reuse we need to compare the file pointers.
1616          */
1617         base = get_file(shp->shm_file);
1618         shp->shm_nattch++;
1619         size = i_size_read(file_inode(base));
1620         ipc_unlock_object(&shp->shm_perm);
1621         rcu_read_unlock();
1622
1623         err = -ENOMEM;
1624         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1625         if (!sfd) {
1626                 fput(base);
1627                 goto out_nattch;
1628         }
1629
1630         file = alloc_file_clone(base, f_flags,
1631                           is_file_hugepages(base) ?
1632                                 &shm_file_operations_huge :
1633                                 &shm_file_operations);
1634         err = PTR_ERR(file);
1635         if (IS_ERR(file)) {
1636                 kfree(sfd);
1637                 fput(base);
1638                 goto out_nattch;
1639         }
1640
1641         sfd->id = shp->shm_perm.id;
1642         sfd->ns = get_ipc_ns(ns);
1643         sfd->file = base;
1644         sfd->vm_ops = NULL;
1645         file->private_data = sfd;
1646
1647         err = security_mmap_file(file, prot, flags);
1648         if (err)
1649                 goto out_fput;
1650
1651         if (mmap_write_lock_killable(current->mm)) {
1652                 err = -EINTR;
1653                 goto out_fput;
1654         }
1655
1656         if (addr && !(shmflg & SHM_REMAP)) {
1657                 err = -EINVAL;
1658                 if (addr + size < addr)
1659                         goto invalid;
1660
1661                 if (find_vma_intersection(current->mm, addr, addr + size))
1662                         goto invalid;
1663         }
1664
1665         addr = do_mmap(file, addr, size, prot, flags, 0, 0, &populate, NULL);
1666         *raddr = addr;
1667         err = 0;
1668         if (IS_ERR_VALUE(addr))
1669                 err = (long)addr;
1670 invalid:
1671         mmap_write_unlock(current->mm);
1672         if (populate)
1673                 mm_populate(addr, populate);
1674
1675 out_fput:
1676         fput(file);
1677
1678 out_nattch:
1679         down_write(&shm_ids(ns).rwsem);
1680         shp = shm_lock(ns, shmid);
1681         shp->shm_nattch--;
1682
1683         if (shm_may_destroy(shp))
1684                 shm_destroy(ns, shp);
1685         else
1686                 shm_unlock(shp);
1687         up_write(&shm_ids(ns).rwsem);
1688         return err;
1689
1690 out_unlock:
1691         rcu_read_unlock();
1692 out:
1693         return err;
1694 }
1695
1696 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1697 {
1698         unsigned long ret;
1699         long err;
1700
1701         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1702         if (err)
1703                 return err;
1704         force_successful_syscall_return();
1705         return (long)ret;
1706 }
1707
1708 #ifdef CONFIG_COMPAT
1709
1710 #ifndef COMPAT_SHMLBA
1711 #define COMPAT_SHMLBA   SHMLBA
1712 #endif
1713
1714 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1715 {
1716         unsigned long ret;
1717         long err;
1718
1719         err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1720         if (err)
1721                 return err;
1722         force_successful_syscall_return();
1723         return (long)ret;
1724 }
1725 #endif
1726
1727 /*
1728  * detach and kill segment if marked destroyed.
1729  * The work is done in shm_close.
1730  */
1731 long ksys_shmdt(char __user *shmaddr)
1732 {
1733         struct mm_struct *mm = current->mm;
1734         struct vm_area_struct *vma;
1735         unsigned long addr = (unsigned long)shmaddr;
1736         int retval = -EINVAL;
1737 #ifdef CONFIG_MMU
1738         loff_t size = 0;
1739         struct file *file;
1740         VMA_ITERATOR(vmi, mm, addr);
1741 #endif
1742
1743         if (addr & ~PAGE_MASK)
1744                 return retval;
1745
1746         if (mmap_write_lock_killable(mm))
1747                 return -EINTR;
1748
1749         /*
1750          * This function tries to be smart and unmap shm segments that
1751          * were modified by partial mlock or munmap calls:
1752          * - It first determines the size of the shm segment that should be
1753          *   unmapped: It searches for a vma that is backed by shm and that
1754          *   started at address shmaddr. It records it's size and then unmaps
1755          *   it.
1756          * - Then it unmaps all shm vmas that started at shmaddr and that
1757          *   are within the initially determined size and that are from the
1758          *   same shm segment from which we determined the size.
1759          * Errors from do_munmap are ignored: the function only fails if
1760          * it's called with invalid parameters or if it's called to unmap
1761          * a part of a vma. Both calls in this function are for full vmas,
1762          * the parameters are directly copied from the vma itself and always
1763          * valid - therefore do_munmap cannot fail. (famous last words?)
1764          */
1765         /*
1766          * If it had been mremap()'d, the starting address would not
1767          * match the usual checks anyway. So assume all vma's are
1768          * above the starting address given.
1769          */
1770
1771 #ifdef CONFIG_MMU
1772         for_each_vma(vmi, vma) {
1773                 /*
1774                  * Check if the starting address would match, i.e. it's
1775                  * a fragment created by mprotect() and/or munmap(), or it
1776                  * otherwise it starts at this address with no hassles.
1777                  */
1778                 if ((vma->vm_ops == &shm_vm_ops) &&
1779                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1780
1781                         /*
1782                          * Record the file of the shm segment being
1783                          * unmapped.  With mremap(), someone could place
1784                          * page from another segment but with equal offsets
1785                          * in the range we are unmapping.
1786                          */
1787                         file = vma->vm_file;
1788                         size = i_size_read(file_inode(vma->vm_file));
1789                         do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
1790                                       NULL, false);
1791                         /*
1792                          * We discovered the size of the shm segment, so
1793                          * break out of here and fall through to the next
1794                          * loop that uses the size information to stop
1795                          * searching for matching vma's.
1796                          */
1797                         retval = 0;
1798                         vma = vma_next(&vmi);
1799                         break;
1800                 }
1801         }
1802
1803         /*
1804          * We need look no further than the maximum address a fragment
1805          * could possibly have landed at. Also cast things to loff_t to
1806          * prevent overflows and make comparisons vs. equal-width types.
1807          */
1808         size = PAGE_ALIGN(size);
1809         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1810                 /* finding a matching vma now does not alter retval */
1811                 if ((vma->vm_ops == &shm_vm_ops) &&
1812                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1813                     (vma->vm_file == file)) {
1814                         do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
1815                                       NULL, false);
1816                 }
1817
1818                 vma = vma_next(&vmi);
1819         }
1820
1821 #else   /* CONFIG_MMU */
1822         vma = vma_lookup(mm, addr);
1823         /* under NOMMU conditions, the exact address to be destroyed must be
1824          * given
1825          */
1826         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1827                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1828                 retval = 0;
1829         }
1830
1831 #endif
1832
1833         mmap_write_unlock(mm);
1834         return retval;
1835 }
1836
1837 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1838 {
1839         return ksys_shmdt(shmaddr);
1840 }
1841
1842 #ifdef CONFIG_PROC_FS
1843 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1844 {
1845         struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1846         struct user_namespace *user_ns = seq_user_ns(s);
1847         struct kern_ipc_perm *ipcp = it;
1848         struct shmid_kernel *shp;
1849         unsigned long rss = 0, swp = 0;
1850
1851         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1852         shm_add_rss_swap(shp, &rss, &swp);
1853
1854 #if BITS_PER_LONG <= 32
1855 #define SIZE_SPEC "%10lu"
1856 #else
1857 #define SIZE_SPEC "%21lu"
1858 #endif
1859
1860         seq_printf(s,
1861                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1862                    "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1863                    SIZE_SPEC " " SIZE_SPEC "\n",
1864                    shp->shm_perm.key,
1865                    shp->shm_perm.id,
1866                    shp->shm_perm.mode,
1867                    shp->shm_segsz,
1868                    pid_nr_ns(shp->shm_cprid, pid_ns),
1869                    pid_nr_ns(shp->shm_lprid, pid_ns),
1870                    shp->shm_nattch,
1871                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1872                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1873                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1874                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1875                    shp->shm_atim,
1876                    shp->shm_dtim,
1877                    shp->shm_ctim,
1878                    rss * PAGE_SIZE,
1879                    swp * PAGE_SIZE);
1880
1881         return 0;
1882 }
1883 #endif