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 user_struct      *mlock_user;
  64
  65         /* The task created the shm object.  NULL if the task is dead. */
  66         struct task_struct      *shm_creator;
  67         struct list_head        shm_clist;      /* list by creator */
  68 } __randomize_layout;
  69
  70 /* shm_mode upper byte flags */
  71 #define SHM_DEST        01000   /* segment will be destroyed on last detach */
  72 #define SHM_LOCKED      02000   /* segment will not be swapped */
  73
  74 struct shm_file_data {
  75         int id;
  76         struct ipc_namespace *ns;
  77         struct file *file;
  78         const struct vm_operations_struct *vm_ops;
  79 };
  80
  81 #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  82
  83 static const struct file_operations shm_file_operations;
  84 static const struct vm_operations_struct shm_vm_ops;
  85
  86 #define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
  87
  88 #define shm_unlock(shp)                 \
  89         ipc_unlock(&(shp)->shm_perm)
  90
  91 static int newseg(struct ipc_namespace *, struct ipc_params *);
  92 static void shm_open(struct vm_area_struct *vma);
  93 static void shm_close(struct vm_area_struct *vma);
  94 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
  95 #ifdef CONFIG_PROC_FS
  96 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  97 #endif
  98
  99 void shm_init_ns(struct ipc_namespace *ns)
 100 {
 101         ns->shm_ctlmax = SHMMAX;
 102         ns->shm_ctlall = SHMALL;
 103         ns->shm_ctlmni = SHMMNI;
 104         ns->shm_rmid_forced = 0;
 105         ns->shm_tot = 0;
 106         ipc_init_ids(&shm_ids(ns));
 107 }
 108
 109 /*
 110  * Called with shm_ids.rwsem (writer) and the shp structure locked.
 111  * Only shm_ids.rwsem remains locked on exit.
 112  */
 113 static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
 114 {
 115         struct shmid_kernel *shp;
 116
 117         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 118
 119         if (shp->shm_nattch) {
 120                 shp->shm_perm.mode |= SHM_DEST;
 121                 /* Do not find it any more */
 122                 ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
 123                 shm_unlock(shp);
 124         } else
 125                 shm_destroy(ns, shp);
 126 }
 127
 128 #ifdef CONFIG_IPC_NS
 129 void shm_exit_ns(struct ipc_namespace *ns)
 130 {
 131         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 132         idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 133         rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
 134 }
 135 #endif
 136
 137 static int __init ipc_ns_init(void)
 138 {
 139         shm_init_ns(&init_ipc_ns);
 140         return 0;
 141 }
 142
 143 pure_initcall(ipc_ns_init);
 144
 145 void __init shm_init(void)
 146 {
 147         ipc_init_proc_interface("sysvipc/shm",
 148 #if BITS_PER_LONG <= 32
 149                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 150 #else
 151                                 "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 152 #endif
 153                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 154 }
 155
 156 static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 157 {
 158         struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 159
 160         if (IS_ERR(ipcp))
 161                 return ERR_CAST(ipcp);
 162
 163         return container_of(ipcp, struct shmid_kernel, shm_perm);
 164 }
 165
 166 static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 167 {
 168         struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 169
 170         if (IS_ERR(ipcp))
 171                 return ERR_CAST(ipcp);
 172
 173         return container_of(ipcp, struct shmid_kernel, shm_perm);
 174 }
 175
 176 /*
 177  * shm_lock_(check_) routines are called in the paths where the rwsem
 178  * is not necessarily held.
 179  */
 180 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 181 {
 182         struct kern_ipc_perm *ipcp;
 183
 184         rcu_read_lock();
 185         ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
 186         if (IS_ERR(ipcp))
 187                 goto err;
 188
 189         ipc_lock_object(ipcp);
 190         /*
 191          * ipc_rmid() may have already freed the ID while ipc_lock_object()
 192          * was spinning: here verify that the structure is still valid.
 193          * Upon races with RMID, return -EIDRM, thus indicating that
 194          * the ID points to a removed identifier.
 195          */
 196         if (ipc_valid_object(ipcp)) {
 197                 /* return a locked ipc object upon success */
 198                 return container_of(ipcp, struct shmid_kernel, shm_perm);
 199         }
 200
 201         ipc_unlock_object(ipcp);
 202         ipcp = ERR_PTR(-EIDRM);
 203 err:
 204         rcu_read_unlock();
 205         /*
 206          * Callers of shm_lock() must validate the status of the returned ipc
 207          * object pointer and error out as appropriate.
 208          */
 209         return ERR_CAST(ipcp);
 210 }
 211
 212 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 213 {
 214         rcu_read_lock();
 215         ipc_lock_object(&ipcp->shm_perm);
 216 }
 217
 218 static void shm_rcu_free(struct rcu_head *head)
 219 {
 220         struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
 221                                                         rcu);
 222         struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
 223                                                         shm_perm);
 224         security_shm_free(&shp->shm_perm);
 225         kvfree(shp);
 226 }
 227
 228 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 229 {
 230         list_del(&s->shm_clist);
 231         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 232 }
 233
 234
 235 static int __shm_open(struct vm_area_struct *vma)
 236 {
 237         struct file *file = vma->vm_file;
 238         struct shm_file_data *sfd = shm_file_data(file);
 239         struct shmid_kernel *shp;
 240
 241         shp = shm_lock(sfd->ns, sfd->id);
 242
 243         if (IS_ERR(shp))
 244                 return PTR_ERR(shp);
 245
 246         if (shp->shm_file != sfd->file) {
 247                 /* ID was reused */
 248                 shm_unlock(shp);
 249                 return -EINVAL;
 250         }
 251
 252         shp->shm_atim = ktime_get_real_seconds();
 253         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 254         shp->shm_nattch++;
 255         shm_unlock(shp);
 256         return 0;
 257 }
 258
 259 /* This is called by fork, once for every shm attach. */
 260 static void shm_open(struct vm_area_struct *vma)
 261 {
 262         int err = __shm_open(vma);
 263         /*
 264          * We raced in the idr lookup or with shm_destroy().
 265          * Either way, the ID is busted.
 266          */
 267         WARN_ON_ONCE(err);
 268 }
 269
 270 /*
 271  * shm_destroy - free the struct shmid_kernel
 272  *
 273  * @ns: namespace
 274  * @shp: struct to free
 275  *
 276  * It has to be called with shp and shm_ids.rwsem (writer) locked,
 277  * but returns with shp unlocked and freed.
 278  */
 279 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 280 {
 281         struct file *shm_file;
 282
 283         shm_file = shp->shm_file;
 284         shp->shm_file = NULL;
 285         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 286         shm_rmid(ns, shp);
 287         shm_unlock(shp);
 288         if (!is_file_hugepages(shm_file))
 289                 shmem_lock(shm_file, 0, shp->mlock_user);
 290         else if (shp->mlock_user)
 291                 user_shm_unlock(i_size_read(file_inode(shm_file)),
 292                                 shp->mlock_user);
 293         fput(shm_file);
 294         ipc_update_pid(&shp->shm_cprid, NULL);
 295         ipc_update_pid(&shp->shm_lprid, NULL);
 296         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 297 }
 298
 299 /*
 300  * shm_may_destroy - identifies whether shm segment should be destroyed now
 301  *
 302  * Returns true if and only if there are no active users of the segment and
 303  * one of the following is true:
 304  *
 305  * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 306  *
 307  * 2) sysctl kernel.shm_rmid_forced is set to 1.
 308  */
 309 static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 310 {
 311         return (shp->shm_nattch == 0) &&
 312                (ns->shm_rmid_forced ||
 313                 (shp->shm_perm.mode & SHM_DEST));
 314 }
 315
 316 /*
 317  * remove the attach descriptor vma.
 318  * free memory for segment if it is marked destroyed.
 319  * The descriptor has already been removed from the current->mm->mmap list
 320  * and will later be kfree()d.
 321  */
 322 static void shm_close(struct vm_area_struct *vma)
 323 {
 324         struct file *file = vma->vm_file;
 325         struct shm_file_data *sfd = shm_file_data(file);
 326         struct shmid_kernel *shp;
 327         struct ipc_namespace *ns = sfd->ns;
 328
 329         down_write(&shm_ids(ns).rwsem);
 330         /* remove from the list of attaches of the shm segment */
 331         shp = shm_lock(ns, sfd->id);
 332
 333         /*
 334          * We raced in the idr lookup or with shm_destroy().
 335          * Either way, the ID is busted.
 336          */
 337         if (WARN_ON_ONCE(IS_ERR(shp)))
 338                 goto done; /* no-op */
 339
 340         ipc_update_pid(&shp->shm_lprid, task_tgid(current));
 341         shp->shm_dtim = ktime_get_real_seconds();
 342         shp->shm_nattch--;
 343         if (shm_may_destroy(ns, shp))
 344                 shm_destroy(ns, shp);
 345         else
 346                 shm_unlock(shp);
 347 done:
 348         up_write(&shm_ids(ns).rwsem);
 349 }
 350
 351 /* Called with ns->shm_ids(ns).rwsem locked */
 352 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 353 {
 354         struct ipc_namespace *ns = data;
 355         struct kern_ipc_perm *ipcp = p;
 356         struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 357
 358         /*
 359          * We want to destroy segments without users and with already
 360          * exit'ed originating process.
 361          *
 362          * As shp->* are changed under rwsem, it's safe to skip shp locking.
 363          */
 364         if (shp->shm_creator != NULL)
 365                 return 0;
 366
 367         if (shm_may_destroy(ns, shp)) {
 368                 shm_lock_by_ptr(shp);
 369                 shm_destroy(ns, shp);
 370         }
 371         return 0;
 372 }
 373
 374 void shm_destroy_orphaned(struct ipc_namespace *ns)
 375 {
 376         down_write(&shm_ids(ns).rwsem);
 377         if (shm_ids(ns).in_use)
 378                 idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 379         up_write(&shm_ids(ns).rwsem);
 380 }
 381
 382 /* Locking assumes this will only be called with task == current */
 383 void exit_shm(struct task_struct *task)
 384 {
 385         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 386         struct shmid_kernel *shp, *n;
 387
 388         if (list_empty(&task->sysvshm.shm_clist))
 389                 return;
 390
 391         /*
 392          * If kernel.shm_rmid_forced is not set then only keep track of
 393          * which shmids are orphaned, so that a later set of the sysctl
 394          * can clean them up.
 395          */
 396         if (!ns->shm_rmid_forced) {
 397                 down_read(&shm_ids(ns).rwsem);
 398                 list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
 399                         shp->shm_creator = NULL;
 400                 /*
 401                  * Only under read lock but we are only called on current
 402                  * so no entry on the list will be shared.
 403                  */
 404                 list_del(&task->sysvshm.shm_clist);
 405                 up_read(&shm_ids(ns).rwsem);
 406                 return;
 407         }
 408
 409         /*
 410          * Destroy all already created segments, that were not yet mapped,
 411          * and mark any mapped as orphan to cover the sysctl toggling.
 412          * Destroy is skipped if shm_may_destroy() returns false.
 413          */
 414         down_write(&shm_ids(ns).rwsem);
 415         list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
 416                 shp->shm_creator = NULL;
 417
 418                 if (shm_may_destroy(ns, shp)) {
 419                         shm_lock_by_ptr(shp);
 420                         shm_destroy(ns, shp);
 421                 }
 422         }
 423
 424         /* Remove the list head from any segments still attached. */
 425         list_del(&task->sysvshm.shm_clist);
 426         up_write(&shm_ids(ns).rwsem);
 427 }
 428
 429 static vm_fault_t shm_fault(struct vm_fault *vmf)
 430 {
 431         struct file *file = vmf->vma->vm_file;
 432         struct shm_file_data *sfd = shm_file_data(file);
 433
 434         return sfd->vm_ops->fault(vmf);
 435 }
 436
 437 static int shm_may_split(struct vm_area_struct *vma, unsigned long addr)
 438 {
 439         struct file *file = vma->vm_file;
 440         struct shm_file_data *sfd = shm_file_data(file);
 441
 442         if (sfd->vm_ops->may_split)
 443                 return sfd->vm_ops->may_split(vma, addr);
 444
 445         return 0;
 446 }
 447
 448 static unsigned long shm_pagesize(struct vm_area_struct *vma)
 449 {
 450         struct file *file = vma->vm_file;
 451         struct shm_file_data *sfd = shm_file_data(file);
 452
 453         if (sfd->vm_ops->pagesize)
 454                 return sfd->vm_ops->pagesize(vma);
 455
 456         return PAGE_SIZE;
 457 }
 458
 459 #ifdef CONFIG_NUMA
 460 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 461 {
 462         struct file *file = vma->vm_file;
 463         struct shm_file_data *sfd = shm_file_data(file);
 464         int err = 0;
 465
 466         if (sfd->vm_ops->set_policy)
 467                 err = sfd->vm_ops->set_policy(vma, new);
 468         return err;
 469 }
 470
 471 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 472                                         unsigned long addr)
 473 {
 474         struct file *file = vma->vm_file;
 475         struct shm_file_data *sfd = shm_file_data(file);
 476         struct mempolicy *pol = NULL;
 477
 478         if (sfd->vm_ops->get_policy)
 479                 pol = sfd->vm_ops->get_policy(vma, addr);
 480         else if (vma->vm_policy)
 481                 pol = vma->vm_policy;
 482
 483         return pol;
 484 }
 485 #endif
 486
 487 static int shm_mmap(struct file *file, struct vm_area_struct *vma)
 488 {
 489         struct shm_file_data *sfd = shm_file_data(file);
 490         int ret;
 491
 492         /*
 493          * In case of remap_file_pages() emulation, the file can represent an
 494          * IPC ID that was removed, and possibly even reused by another shm
 495          * segment already.  Propagate this case as an error to caller.
 496          */
 497         ret = __shm_open(vma);
 498         if (ret)
 499                 return ret;
 500
 501         ret = call_mmap(sfd->file, vma);
 502         if (ret) {
 503                 shm_close(vma);
 504                 return ret;
 505         }
 506         sfd->vm_ops = vma->vm_ops;
 507 #ifdef CONFIG_MMU
 508         WARN_ON(!sfd->vm_ops->fault);
 509 #endif
 510         vma->vm_ops = &shm_vm_ops;
 511         return 0;
 512 }
 513
 514 static int shm_release(struct inode *ino, struct file *file)
 515 {
 516         struct shm_file_data *sfd = shm_file_data(file);
 517
 518         put_ipc_ns(sfd->ns);
 519         fput(sfd->file);
 520         shm_file_data(file) = NULL;
 521         kfree(sfd);
 522         return 0;
 523 }
 524
 525 static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 526 {
 527         struct shm_file_data *sfd = shm_file_data(file);
 528
 529         if (!sfd->file->f_op->fsync)
 530                 return -EINVAL;
 531         return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 532 }
 533
 534 static long shm_fallocate(struct file *file, int mode, loff_t offset,
 535                           loff_t len)
 536 {
 537         struct shm_file_data *sfd = shm_file_data(file);
 538
 539         if (!sfd->file->f_op->fallocate)
 540                 return -EOPNOTSUPP;
 541         return sfd->file->f_op->fallocate(file, mode, offset, len);
 542 }
 543
 544 static unsigned long shm_get_unmapped_area(struct file *file,
 545         unsigned long addr, unsigned long len, unsigned long pgoff,
 546         unsigned long flags)
 547 {
 548         struct shm_file_data *sfd = shm_file_data(file);
 549
 550         return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 551                                                 pgoff, flags);
 552 }
 553
 554 static const struct file_operations shm_file_operations = {
 555         .mmap           = shm_mmap,
 556         .fsync          = shm_fsync,
 557         .release        = shm_release,
 558         .get_unmapped_area      = shm_get_unmapped_area,
 559         .llseek         = noop_llseek,
 560         .fallocate      = shm_fallocate,
 561 };
 562
 563 /*
 564  * shm_file_operations_huge is now identical to shm_file_operations,
 565  * but we keep it distinct for the sake of is_file_shm_hugepages().
 566  */
 567 static const struct file_operations shm_file_operations_huge = {
 568         .mmap           = shm_mmap,
 569         .fsync          = shm_fsync,
 570         .release        = shm_release,
 571         .get_unmapped_area      = shm_get_unmapped_area,
 572         .llseek         = noop_llseek,
 573         .fallocate      = shm_fallocate,
 574 };
 575
 576 bool is_file_shm_hugepages(struct file *file)
 577 {
 578         return file->f_op == &shm_file_operations_huge;
 579 }
 580
 581 static const struct vm_operations_struct shm_vm_ops = {
 582         .open   = shm_open,     /* callback for a new vm-area open */
 583         .close  = shm_close,    /* callback for when the vm-area is released */
 584         .fault  = shm_fault,
 585         .may_split = shm_may_split,
 586         .pagesize = shm_pagesize,
 587 #if defined(CONFIG_NUMA)
 588         .set_policy = shm_set_policy,
 589         .get_policy = shm_get_policy,
 590 #endif
 591 };
 592
 593 /**
 594  * newseg - Create a new shared memory segment
 595  * @ns: namespace
 596  * @params: ptr to the structure that contains key, size and shmflg
 597  *
 598  * Called with shm_ids.rwsem held as a writer.
 599  */
 600 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 601 {
 602         key_t key = params->key;
 603         int shmflg = params->flg;
 604         size_t size = params->u.size;
 605         int error;
 606         struct shmid_kernel *shp;
 607         size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 608         struct file *file;
 609         char name[13];
 610         vm_flags_t acctflag = 0;
 611
 612         if (size < SHMMIN || size > ns->shm_ctlmax)
 613                 return -EINVAL;
 614
 615         if (numpages << PAGE_SHIFT < size)
 616                 return -ENOSPC;
 617
 618         if (ns->shm_tot + numpages < ns->shm_tot ||
 619                         ns->shm_tot + numpages > ns->shm_ctlall)
 620                 return -ENOSPC;
 621
 622         shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
 623         if (unlikely(!shp))
 624                 return -ENOMEM;
 625
 626         shp->shm_perm.key = key;
 627         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 628         shp->mlock_user = NULL;
 629
 630         shp->shm_perm.security = NULL;
 631         error = security_shm_alloc(&shp->shm_perm);
 632         if (error) {
 633                 kvfree(shp);
 634                 return error;
 635         }
 636
 637         sprintf(name, "SYSV%08x", key);
 638         if (shmflg & SHM_HUGETLB) {
 639                 struct hstate *hs;
 640                 size_t hugesize;
 641
 642                 hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 643                 if (!hs) {
 644                         error = -EINVAL;
 645                         goto no_file;
 646                 }
 647                 hugesize = ALIGN(size, huge_page_size(hs));
 648
 649                 /* hugetlb_file_setup applies strict accounting */
 650                 if (shmflg & SHM_NORESERVE)
 651                         acctflag = VM_NORESERVE;
 652                 file = hugetlb_file_setup(name, hugesize, acctflag,
 653                                   &shp->mlock_user, HUGETLB_SHMFS_INODE,
 654                                 (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 655         } else {
 656                 /*
 657                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
 658                  * if it's asked for.
 659                  */
 660                 if  ((shmflg & SHM_NORESERVE) &&
 661                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 662                         acctflag = VM_NORESERVE;
 663                 file = shmem_kernel_file_setup(name, size, acctflag);
 664         }
 665         error = PTR_ERR(file);
 666         if (IS_ERR(file))
 667                 goto no_file;
 668
 669         shp->shm_cprid = get_pid(task_tgid(current));
 670         shp->shm_lprid = NULL;
 671         shp->shm_atim = shp->shm_dtim = 0;
 672         shp->shm_ctim = ktime_get_real_seconds();
 673         shp->shm_segsz = size;
 674         shp->shm_nattch = 0;
 675         shp->shm_file = file;
 676         shp->shm_creator = current;
 677
 678         /* ipc_addid() locks shp upon success. */
 679         error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 680         if (error < 0)
 681                 goto no_id;
 682
 683         list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 684
 685         /*
 686          * shmid gets reported as "inode#" in /proc/pid/maps.
 687          * proc-ps tools use this. Changing this will break them.
 688          */
 689         file_inode(file)->i_ino = shp->shm_perm.id;
 690
 691         ns->shm_tot += numpages;
 692         error = shp->shm_perm.id;
 693
 694         ipc_unlock_object(&shp->shm_perm);
 695         rcu_read_unlock();
 696         return error;
 697
 698 no_id:
 699         ipc_update_pid(&shp->shm_cprid, NULL);
 700         ipc_update_pid(&shp->shm_lprid, NULL);
 701         if (is_file_hugepages(file) && shp->mlock_user)
 702                 user_shm_unlock(size, shp->mlock_user);
 703         fput(file);
 704         ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
 705         return error;
 706 no_file:
 707         call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
 708         return error;
 709 }
 710
 711 /*
 712  * Called with shm_ids.rwsem and ipcp locked.
 713  */
 714 static int shm_more_checks(struct kern_ipc_perm *ipcp, struct ipc_params *params)
 715 {
 716         struct shmid_kernel *shp;
 717
 718         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 719         if (shp->shm_segsz < params->u.size)
 720                 return -EINVAL;
 721
 722         return 0;
 723 }
 724
 725 long ksys_shmget(key_t key, size_t size, int shmflg)
 726 {
 727         struct ipc_namespace *ns;
 728         static const struct ipc_ops shm_ops = {
 729                 .getnew = newseg,
 730                 .associate = security_shm_associate,
 731                 .more_checks = shm_more_checks,
 732         };
 733         struct ipc_params shm_params;
 734
 735         ns = current->nsproxy->ipc_ns;
 736
 737         shm_params.key = key;
 738         shm_params.flg = shmflg;
 739         shm_params.u.size = size;
 740
 741         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 742 }
 743
 744 SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 745 {
 746         return ksys_shmget(key, size, shmflg);
 747 }
 748
 749 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 750 {
 751         switch (version) {
 752         case IPC_64:
 753                 return copy_to_user(buf, in, sizeof(*in));
 754         case IPC_OLD:
 755             {
 756                 struct shmid_ds out;
 757
 758                 memset(&out, 0, sizeof(out));
 759                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 760                 out.shm_segsz   = in->shm_segsz;
 761                 out.shm_atime   = in->shm_atime;
 762                 out.shm_dtime   = in->shm_dtime;
 763                 out.shm_ctime   = in->shm_ctime;
 764                 out.shm_cpid    = in->shm_cpid;
 765                 out.shm_lpid    = in->shm_lpid;
 766                 out.shm_nattch  = in->shm_nattch;
 767
 768                 return copy_to_user(buf, &out, sizeof(out));
 769             }
 770         default:
 771                 return -EINVAL;
 772         }
 773 }
 774
 775 static inline unsigned long
 776 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 777 {
 778         switch (version) {
 779         case IPC_64:
 780                 if (copy_from_user(out, buf, sizeof(*out)))
 781                         return -EFAULT;
 782                 return 0;
 783         case IPC_OLD:
 784             {
 785                 struct shmid_ds tbuf_old;
 786
 787                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 788                         return -EFAULT;
 789
 790                 out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 791                 out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 792                 out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 793
 794                 return 0;
 795             }
 796         default:
 797                 return -EINVAL;
 798         }
 799 }
 800
 801 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 802 {
 803         switch (version) {
 804         case IPC_64:
 805                 return copy_to_user(buf, in, sizeof(*in));
 806         case IPC_OLD:
 807             {
 808                 struct shminfo out;
 809
 810                 if (in->shmmax > INT_MAX)
 811                         out.shmmax = INT_MAX;
 812                 else
 813                         out.shmmax = (int)in->shmmax;
 814
 815                 out.shmmin      = in->shmmin;
 816                 out.shmmni      = in->shmmni;
 817                 out.shmseg      = in->shmseg;
 818                 out.shmall      = in->shmall;
 819
 820                 return copy_to_user(buf, &out, sizeof(out));
 821             }
 822         default:
 823                 return -EINVAL;
 824         }
 825 }
 826
 827 /*
 828  * Calculate and add used RSS and swap pages of a shm.
 829  * Called with shm_ids.rwsem held as a reader
 830  */
 831 static void shm_add_rss_swap(struct shmid_kernel *shp,
 832         unsigned long *rss_add, unsigned long *swp_add)
 833 {
 834         struct inode *inode;
 835
 836         inode = file_inode(shp->shm_file);
 837
 838         if (is_file_hugepages(shp->shm_file)) {
 839                 struct address_space *mapping = inode->i_mapping;
 840                 struct hstate *h = hstate_file(shp->shm_file);
 841                 *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 842         } else {
 843 #ifdef CONFIG_SHMEM
 844                 struct shmem_inode_info *info = SHMEM_I(inode);
 845
 846                 spin_lock_irq(&info->lock);
 847                 *rss_add += inode->i_mapping->nrpages;
 848                 *swp_add += info->swapped;
 849                 spin_unlock_irq(&info->lock);
 850 #else
 851                 *rss_add += inode->i_mapping->nrpages;
 852 #endif
 853         }
 854 }
 855
 856 /*
 857  * Called with shm_ids.rwsem held as a reader
 858  */
 859 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 860                 unsigned long *swp)
 861 {
 862         int next_id;
 863         int total, in_use;
 864
 865         *rss = 0;
 866         *swp = 0;
 867
 868         in_use = shm_ids(ns).in_use;
 869
 870         for (total = 0, next_id = 0; total < in_use; next_id++) {
 871                 struct kern_ipc_perm *ipc;
 872                 struct shmid_kernel *shp;
 873
 874                 ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 875                 if (ipc == NULL)
 876                         continue;
 877                 shp = container_of(ipc, struct shmid_kernel, shm_perm);
 878
 879                 shm_add_rss_swap(shp, rss, swp);
 880
 881                 total++;
 882         }
 883 }
 884
 885 /*
 886  * This function handles some shmctl commands which require the rwsem
 887  * to be held in write mode.
 888  * NOTE: no locks must be held, the rwsem is taken inside this function.
 889  */
 890 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 891                        struct shmid64_ds *shmid64)
 892 {
 893         struct kern_ipc_perm *ipcp;
 894         struct shmid_kernel *shp;
 895         int err;
 896
 897         down_write(&shm_ids(ns).rwsem);
 898         rcu_read_lock();
 899
 900         ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
 901                                       &shmid64->shm_perm, 0);
 902         if (IS_ERR(ipcp)) {
 903                 err = PTR_ERR(ipcp);
 904                 goto out_unlock1;
 905         }
 906
 907         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 908
 909         err = security_shm_shmctl(&shp->shm_perm, cmd);
 910         if (err)
 911                 goto out_unlock1;
 912
 913         switch (cmd) {
 914         case IPC_RMID:
 915                 ipc_lock_object(&shp->shm_perm);
 916                 /* do_shm_rmid unlocks the ipc object and rcu */
 917                 do_shm_rmid(ns, ipcp);
 918                 goto out_up;
 919         case IPC_SET:
 920                 ipc_lock_object(&shp->shm_perm);
 921                 err = ipc_update_perm(&shmid64->shm_perm, ipcp);
 922                 if (err)
 923                         goto out_unlock0;
 924                 shp->shm_ctim = ktime_get_real_seconds();
 925                 break;
 926         default:
 927                 err = -EINVAL;
 928                 goto out_unlock1;
 929         }
 930
 931 out_unlock0:
 932         ipc_unlock_object(&shp->shm_perm);
 933 out_unlock1:
 934         rcu_read_unlock();
 935 out_up:
 936         up_write(&shm_ids(ns).rwsem);
 937         return err;
 938 }
 939
 940 static int shmctl_ipc_info(struct ipc_namespace *ns,
 941                            struct shminfo64 *shminfo)
 942 {
 943         int err = security_shm_shmctl(NULL, IPC_INFO);
 944         if (!err) {
 945                 memset(shminfo, 0, sizeof(*shminfo));
 946                 shminfo->shmmni = shminfo->shmseg = ns->shm_ctlmni;
 947                 shminfo->shmmax = ns->shm_ctlmax;
 948                 shminfo->shmall = ns->shm_ctlall;
 949                 shminfo->shmmin = SHMMIN;
 950                 down_read(&shm_ids(ns).rwsem);
 951                 err = ipc_get_maxidx(&shm_ids(ns));
 952                 up_read(&shm_ids(ns).rwsem);
 953                 if (err < 0)
 954                         err = 0;
 955         }
 956         return err;
 957 }
 958
 959 static int shmctl_shm_info(struct ipc_namespace *ns,
 960                            struct shm_info *shm_info)
 961 {
 962         int err = security_shm_shmctl(NULL, SHM_INFO);
 963         if (!err) {
 964                 memset(shm_info, 0, sizeof(*shm_info));
 965                 down_read(&shm_ids(ns).rwsem);
 966                 shm_info->used_ids = shm_ids(ns).in_use;
 967                 shm_get_stat(ns, &shm_info->shm_rss, &shm_info->shm_swp);
 968                 shm_info->shm_tot = ns->shm_tot;
 969                 shm_info->swap_attempts = 0;
 970                 shm_info->swap_successes = 0;
 971                 err = ipc_get_maxidx(&shm_ids(ns));
 972                 up_read(&shm_ids(ns).rwsem);
 973                 if (err < 0)
 974                         err = 0;
 975         }
 976         return err;
 977 }
 978
 979 static int shmctl_stat(struct ipc_namespace *ns, int shmid,
 980                         int cmd, struct shmid64_ds *tbuf)
 981 {
 982         struct shmid_kernel *shp;
 983         int err;
 984
 985         memset(tbuf, 0, sizeof(*tbuf));
 986
 987         rcu_read_lock();
 988         if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
 989                 shp = shm_obtain_object(ns, shmid);
 990                 if (IS_ERR(shp)) {
 991                         err = PTR_ERR(shp);
 992                         goto out_unlock;
 993                 }
 994         } else { /* IPC_STAT */
 995                 shp = shm_obtain_object_check(ns, shmid);
 996                 if (IS_ERR(shp)) {
 997                         err = PTR_ERR(shp);
 998                         goto out_unlock;
 999                 }
1000         }
1001
1002         /*
1003          * Semantically SHM_STAT_ANY ought to be identical to
1004          * that functionality provided by the /proc/sysvipc/
1005          * interface. As such, only audit these calls and
1006          * do not do traditional S_IRUGO permission checks on
1007          * the ipc object.
1008          */
1009         if (cmd == SHM_STAT_ANY)
1010                 audit_ipc_obj(&shp->shm_perm);
1011         else {
1012                 err = -EACCES;
1013                 if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
1014                         goto out_unlock;
1015         }
1016
1017         err = security_shm_shmctl(&shp->shm_perm, cmd);
1018         if (err)
1019                 goto out_unlock;
1020
1021         ipc_lock_object(&shp->shm_perm);
1022
1023         if (!ipc_valid_object(&shp->shm_perm)) {
1024                 ipc_unlock_object(&shp->shm_perm);
1025                 err = -EIDRM;
1026                 goto out_unlock;
1027         }
1028
1029         kernel_to_ipc64_perm(&shp->shm_perm, &tbuf->shm_perm);
1030         tbuf->shm_segsz = shp->shm_segsz;
1031         tbuf->shm_atime = shp->shm_atim;
1032         tbuf->shm_dtime = shp->shm_dtim;
1033         tbuf->shm_ctime = shp->shm_ctim;
1034 #ifndef CONFIG_64BIT
1035         tbuf->shm_atime_high = shp->shm_atim >> 32;
1036         tbuf->shm_dtime_high = shp->shm_dtim >> 32;
1037         tbuf->shm_ctime_high = shp->shm_ctim >> 32;
1038 #endif
1039         tbuf->shm_cpid  = pid_vnr(shp->shm_cprid);
1040         tbuf->shm_lpid  = pid_vnr(shp->shm_lprid);
1041         tbuf->shm_nattch = shp->shm_nattch;
1042
1043         if (cmd == IPC_STAT) {
1044                 /*
1045                  * As defined in SUS:
1046                  * Return 0 on success
1047                  */
1048                 err = 0;
1049         } else {
1050                 /*
1051                  * SHM_STAT and SHM_STAT_ANY (both Linux specific)
1052                  * Return the full id, including the sequence number
1053                  */
1054                 err = shp->shm_perm.id;
1055         }
1056
1057         ipc_unlock_object(&shp->shm_perm);
1058 out_unlock:
1059         rcu_read_unlock();
1060         return err;
1061 }
1062
1063 static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
1064 {
1065         struct shmid_kernel *shp;
1066         struct file *shm_file;
1067         int err;
1068
1069         rcu_read_lock();
1070         shp = shm_obtain_object_check(ns, shmid);
1071         if (IS_ERR(shp)) {
1072                 err = PTR_ERR(shp);
1073                 goto out_unlock1;
1074         }
1075
1076         audit_ipc_obj(&(shp->shm_perm));
1077         err = security_shm_shmctl(&shp->shm_perm, cmd);
1078         if (err)
1079                 goto out_unlock1;
1080
1081         ipc_lock_object(&shp->shm_perm);
1082
1083         /* check if shm_destroy() is tearing down shp */
1084         if (!ipc_valid_object(&shp->shm_perm)) {
1085                 err = -EIDRM;
1086                 goto out_unlock0;
1087         }
1088
1089         if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
1090                 kuid_t euid = current_euid();
1091
1092                 if (!uid_eq(euid, shp->shm_perm.uid) &&
1093                     !uid_eq(euid, shp->shm_perm.cuid)) {
1094                         err = -EPERM;
1095                         goto out_unlock0;
1096                 }
1097                 if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
1098                         err = -EPERM;
1099                         goto out_unlock0;
1100                 }
1101         }
1102
1103         shm_file = shp->shm_file;
1104         if (is_file_hugepages(shm_file))
1105                 goto out_unlock0;
1106
1107         if (cmd == SHM_LOCK) {
1108                 struct user_struct *user = current_user();
1109
1110                 err = shmem_lock(shm_file, 1, user);
1111                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
1112                         shp->shm_perm.mode |= SHM_LOCKED;
1113                         shp->mlock_user = user;
1114                 }
1115                 goto out_unlock0;
1116         }
1117
1118         /* SHM_UNLOCK */
1119         if (!(shp->shm_perm.mode & SHM_LOCKED))
1120                 goto out_unlock0;
1121         shmem_lock(shm_file, 0, shp->mlock_user);
1122         shp->shm_perm.mode &= ~SHM_LOCKED;
1123         shp->mlock_user = NULL;
1124         get_file(shm_file);
1125         ipc_unlock_object(&shp->shm_perm);
1126         rcu_read_unlock();
1127         shmem_unlock_mapping(shm_file->f_mapping);
1128
1129         fput(shm_file);
1130         return err;
1131
1132 out_unlock0:
1133         ipc_unlock_object(&shp->shm_perm);
1134 out_unlock1:
1135         rcu_read_unlock();
1136         return err;
1137 }
1138
1139 static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
1140 {
1141         int err;
1142         struct ipc_namespace *ns;
1143         struct shmid64_ds sem64;
1144
1145         if (cmd < 0 || shmid < 0)
1146                 return -EINVAL;
1147
1148         ns = current->nsproxy->ipc_ns;
1149
1150         switch (cmd) {
1151         case IPC_INFO: {
1152                 struct shminfo64 shminfo;
1153                 err = shmctl_ipc_info(ns, &shminfo);
1154                 if (err < 0)
1155                         return err;
1156                 if (copy_shminfo_to_user(buf, &shminfo, version))
1157                         err = -EFAULT;
1158                 return err;
1159         }
1160         case SHM_INFO: {
1161                 struct shm_info shm_info;
1162                 err = shmctl_shm_info(ns, &shm_info);
1163                 if (err < 0)
1164                         return err;
1165                 if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
1166                         err = -EFAULT;
1167                 return err;
1168         }
1169         case SHM_STAT:
1170         case SHM_STAT_ANY:
1171         case IPC_STAT: {
1172                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1173                 if (err < 0)
1174                         return err;
1175                 if (copy_shmid_to_user(buf, &sem64, version))
1176                         err = -EFAULT;
1177                 return err;
1178         }
1179         case IPC_SET:
1180                 if (copy_shmid_from_user(&sem64, buf, version))
1181                         return -EFAULT;
1182                 fallthrough;
1183         case IPC_RMID:
1184                 return shmctl_down(ns, shmid, cmd, &sem64);
1185         case SHM_LOCK:
1186         case SHM_UNLOCK:
1187                 return shmctl_do_lock(ns, shmid, cmd);
1188         default:
1189                 return -EINVAL;
1190         }
1191 }
1192
1193 SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1194 {
1195         return ksys_shmctl(shmid, cmd, buf, IPC_64);
1196 }
1197
1198 #ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
1199 long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
1200 {
1201         int version = ipc_parse_version(&cmd);
1202
1203         return ksys_shmctl(shmid, cmd, buf, version);
1204 }
1205
1206 SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
1207 {
1208         return ksys_old_shmctl(shmid, cmd, buf);
1209 }
1210 #endif
1211
1212 #ifdef CONFIG_COMPAT
1213
1214 struct compat_shmid_ds {
1215         struct compat_ipc_perm shm_perm;
1216         int shm_segsz;
1217         old_time32_t shm_atime;
1218         old_time32_t shm_dtime;
1219         old_time32_t shm_ctime;
1220         compat_ipc_pid_t shm_cpid;
1221         compat_ipc_pid_t shm_lpid;
1222         unsigned short shm_nattch;
1223         unsigned short shm_unused;
1224         compat_uptr_t shm_unused2;
1225         compat_uptr_t shm_unused3;
1226 };
1227
1228 struct compat_shminfo64 {
1229         compat_ulong_t shmmax;
1230         compat_ulong_t shmmin;
1231         compat_ulong_t shmmni;
1232         compat_ulong_t shmseg;
1233         compat_ulong_t shmall;
1234         compat_ulong_t __unused1;
1235         compat_ulong_t __unused2;
1236         compat_ulong_t __unused3;
1237         compat_ulong_t __unused4;
1238 };
1239
1240 struct compat_shm_info {
1241         compat_int_t used_ids;
1242         compat_ulong_t shm_tot, shm_rss, shm_swp;
1243         compat_ulong_t swap_attempts, swap_successes;
1244 };
1245
1246 static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
1247                                         int version)
1248 {
1249         if (in->shmmax > INT_MAX)
1250                 in->shmmax = INT_MAX;
1251         if (version == IPC_64) {
1252                 struct compat_shminfo64 info;
1253                 memset(&info, 0, sizeof(info));
1254                 info.shmmax = in->shmmax;
1255                 info.shmmin = in->shmmin;
1256                 info.shmmni = in->shmmni;
1257                 info.shmseg = in->shmseg;
1258                 info.shmall = in->shmall;
1259                 return copy_to_user(buf, &info, sizeof(info));
1260         } else {
1261                 struct shminfo info;
1262                 memset(&info, 0, sizeof(info));
1263                 info.shmmax = in->shmmax;
1264                 info.shmmin = in->shmmin;
1265                 info.shmmni = in->shmmni;
1266                 info.shmseg = in->shmseg;
1267                 info.shmall = in->shmall;
1268                 return copy_to_user(buf, &info, sizeof(info));
1269         }
1270 }
1271
1272 static int put_compat_shm_info(struct shm_info *ip,
1273                                 struct compat_shm_info __user *uip)
1274 {
1275         struct compat_shm_info info;
1276
1277         memset(&info, 0, sizeof(info));
1278         info.used_ids = ip->used_ids;
1279         info.shm_tot = ip->shm_tot;
1280         info.shm_rss = ip->shm_rss;
1281         info.shm_swp = ip->shm_swp;
1282         info.swap_attempts = ip->swap_attempts;
1283         info.swap_successes = ip->swap_successes;
1284         return copy_to_user(uip, &info, sizeof(info));
1285 }
1286
1287 static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
1288                                         int version)
1289 {
1290         if (version == IPC_64) {
1291                 struct compat_shmid64_ds v;
1292                 memset(&v, 0, sizeof(v));
1293                 to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
1294                 v.shm_atime      = lower_32_bits(in->shm_atime);
1295                 v.shm_atime_high = upper_32_bits(in->shm_atime);
1296                 v.shm_dtime      = lower_32_bits(in->shm_dtime);
1297                 v.shm_dtime_high = upper_32_bits(in->shm_dtime);
1298                 v.shm_ctime      = lower_32_bits(in->shm_ctime);
1299                 v.shm_ctime_high = upper_32_bits(in->shm_ctime);
1300                 v.shm_segsz = in->shm_segsz;
1301                 v.shm_nattch = in->shm_nattch;
1302                 v.shm_cpid = in->shm_cpid;
1303                 v.shm_lpid = in->shm_lpid;
1304                 return copy_to_user(buf, &v, sizeof(v));
1305         } else {
1306                 struct compat_shmid_ds v;
1307                 memset(&v, 0, sizeof(v));
1308                 to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
1309                 v.shm_perm.key = in->shm_perm.key;
1310                 v.shm_atime = in->shm_atime;
1311                 v.shm_dtime = in->shm_dtime;
1312                 v.shm_ctime = in->shm_ctime;
1313                 v.shm_segsz = in->shm_segsz;
1314                 v.shm_nattch = in->shm_nattch;
1315                 v.shm_cpid = in->shm_cpid;
1316                 v.shm_lpid = in->shm_lpid;
1317                 return copy_to_user(buf, &v, sizeof(v));
1318         }
1319 }
1320
1321 static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
1322                                         int version)
1323 {
1324         memset(out, 0, sizeof(*out));
1325         if (version == IPC_64) {
1326                 struct compat_shmid64_ds __user *p = buf;
1327                 return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
1328         } else {
1329                 struct compat_shmid_ds __user *p = buf;
1330                 return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
1331         }
1332 }
1333
1334 static long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
1335 {
1336         struct ipc_namespace *ns;
1337         struct shmid64_ds sem64;
1338         int err;
1339
1340         ns = current->nsproxy->ipc_ns;
1341
1342         if (cmd < 0 || shmid < 0)
1343                 return -EINVAL;
1344
1345         switch (cmd) {
1346         case IPC_INFO: {
1347                 struct shminfo64 shminfo;
1348                 err = shmctl_ipc_info(ns, &shminfo);
1349                 if (err < 0)
1350                         return err;
1351                 if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
1352                         err = -EFAULT;
1353                 return err;
1354         }
1355         case SHM_INFO: {
1356                 struct shm_info shm_info;
1357                 err = shmctl_shm_info(ns, &shm_info);
1358                 if (err < 0)
1359                         return err;
1360                 if (put_compat_shm_info(&shm_info, uptr))
1361                         err = -EFAULT;
1362                 return err;
1363         }
1364         case IPC_STAT:
1365         case SHM_STAT_ANY:
1366         case SHM_STAT:
1367                 err = shmctl_stat(ns, shmid, cmd, &sem64);
1368                 if (err < 0)
1369                         return err;
1370                 if (copy_compat_shmid_to_user(uptr, &sem64, version))
1371                         err = -EFAULT;
1372                 return err;
1373
1374         case IPC_SET:
1375                 if (copy_compat_shmid_from_user(&sem64, uptr, version))
1376                         return -EFAULT;
1377                 fallthrough;
1378         case IPC_RMID:
1379                 return shmctl_down(ns, shmid, cmd, &sem64);
1380         case SHM_LOCK:
1381         case SHM_UNLOCK:
1382                 return shmctl_do_lock(ns, shmid, cmd);
1383         default:
1384                 return -EINVAL;
1385         }
1386         return err;
1387 }
1388
1389 COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
1390 {
1391         return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
1392 }
1393
1394 #ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
1395 long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
1396 {
1397         int version = compat_ipc_parse_version(&cmd);
1398
1399         return compat_ksys_shmctl(shmid, cmd, uptr, version);
1400 }
1401
1402 COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
1403 {
1404         return compat_ksys_old_shmctl(shmid, cmd, uptr);
1405 }
1406 #endif
1407 #endif
1408
1409 /*
1410  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1411  *
1412  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1413  * "raddr" thing points to kernel space, and there has to be a wrapper around
1414  * this.
1415  */
1416 long do_shmat(int shmid, char __user *shmaddr, int shmflg,
1417               ulong *raddr, unsigned long shmlba)
1418 {
1419         struct shmid_kernel *shp;
1420         unsigned long addr = (unsigned long)shmaddr;
1421         unsigned long size;
1422         struct file *file, *base;
1423         int    err;
1424         unsigned long flags = MAP_SHARED;
1425         unsigned long prot;
1426         int acc_mode;
1427         struct ipc_namespace *ns;
1428         struct shm_file_data *sfd;
1429         int f_flags;
1430         unsigned long populate = 0;
1431
1432         err = -EINVAL;
1433         if (shmid < 0)
1434                 goto out;
1435
1436         if (addr) {
1437                 if (addr & (shmlba - 1)) {
1438                         if (shmflg & SHM_RND) {
1439                                 addr &= ~(shmlba - 1);  /* round down */
1440
1441                                 /*
1442                                  * Ensure that the round-down is non-nil
1443                                  * when remapping. This can happen for
1444                                  * cases when addr < shmlba.
1445                                  */
1446                                 if (!addr && (shmflg & SHM_REMAP))
1447                                         goto out;
1448                         } else
1449 #ifndef __ARCH_FORCE_SHMLBA
1450                                 if (addr & ~PAGE_MASK)
1451 #endif
1452                                         goto out;
1453                 }
1454
1455                 flags |= MAP_FIXED;
1456         } else if ((shmflg & SHM_REMAP))
1457                 goto out;
1458
1459         if (shmflg & SHM_RDONLY) {
1460                 prot = PROT_READ;
1461                 acc_mode = S_IRUGO;
1462                 f_flags = O_RDONLY;
1463         } else {
1464                 prot = PROT_READ | PROT_WRITE;
1465                 acc_mode = S_IRUGO | S_IWUGO;
1466                 f_flags = O_RDWR;
1467         }
1468         if (shmflg & SHM_EXEC) {
1469                 prot |= PROT_EXEC;
1470                 acc_mode |= S_IXUGO;
1471         }
1472
1473         /*
1474          * We cannot rely on the fs check since SYSV IPC does have an
1475          * additional creator id...
1476          */
1477         ns = current->nsproxy->ipc_ns;
1478         rcu_read_lock();
1479         shp = shm_obtain_object_check(ns, shmid);
1480         if (IS_ERR(shp)) {
1481                 err = PTR_ERR(shp);
1482                 goto out_unlock;
1483         }
1484
1485         err = -EACCES;
1486         if (ipcperms(ns, &shp->shm_perm, acc_mode))
1487                 goto out_unlock;
1488
1489         err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
1490         if (err)
1491                 goto out_unlock;
1492
1493         ipc_lock_object(&shp->shm_perm);
1494
1495         /* check if shm_destroy() is tearing down shp */
1496         if (!ipc_valid_object(&shp->shm_perm)) {
1497                 ipc_unlock_object(&shp->shm_perm);
1498                 err = -EIDRM;
1499                 goto out_unlock;
1500         }
1501
1502         /*
1503          * We need to take a reference to the real shm file to prevent the
1504          * pointer from becoming stale in cases where the lifetime of the outer
1505          * file extends beyond that of the shm segment.  It's not usually
1506          * possible, but it can happen during remap_file_pages() emulation as
1507          * that unmaps the memory, then does ->mmap() via file reference only.
1508          * We'll deny the ->mmap() if the shm segment was since removed, but to
1509          * detect shm ID reuse we need to compare the file pointers.
1510          */
1511         base = get_file(shp->shm_file);
1512         shp->shm_nattch++;
1513         size = i_size_read(file_inode(base));
1514         ipc_unlock_object(&shp->shm_perm);
1515         rcu_read_unlock();
1516
1517         err = -ENOMEM;
1518         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1519         if (!sfd) {
1520                 fput(base);
1521                 goto out_nattch;
1522         }
1523
1524         file = alloc_file_clone(base, f_flags,
1525                           is_file_hugepages(base) ?
1526                                 &shm_file_operations_huge :
1527                                 &shm_file_operations);
1528         err = PTR_ERR(file);
1529         if (IS_ERR(file)) {
1530                 kfree(sfd);
1531                 fput(base);
1532                 goto out_nattch;
1533         }
1534
1535         sfd->id = shp->shm_perm.id;
1536         sfd->ns = get_ipc_ns(ns);
1537         sfd->file = base;
1538         sfd->vm_ops = NULL;
1539         file->private_data = sfd;
1540
1541         err = security_mmap_file(file, prot, flags);
1542         if (err)
1543                 goto out_fput;
1544
1545         if (mmap_write_lock_killable(current->mm)) {
1546                 err = -EINTR;
1547                 goto out_fput;
1548         }
1549
1550         if (addr && !(shmflg & SHM_REMAP)) {
1551                 err = -EINVAL;
1552                 if (addr + size < addr)
1553                         goto invalid;
1554
1555                 if (find_vma_intersection(current->mm, addr, addr + size))
1556                         goto invalid;
1557         }
1558
1559         addr = do_mmap(file, addr, size, prot, flags, 0, &populate, NULL);
1560         *raddr = addr;
1561         err = 0;
1562         if (IS_ERR_VALUE(addr))
1563                 err = (long)addr;
1564 invalid:
1565         mmap_write_unlock(current->mm);
1566         if (populate)
1567                 mm_populate(addr, populate);
1568
1569 out_fput:
1570         fput(file);
1571
1572 out_nattch:
1573         down_write(&shm_ids(ns).rwsem);
1574         shp = shm_lock(ns, shmid);
1575         shp->shm_nattch--;
1576         if (shm_may_destroy(ns, shp))
1577                 shm_destroy(ns, shp);
1578         else
1579                 shm_unlock(shp);
1580         up_write(&shm_ids(ns).rwsem);
1581         return err;
1582
1583 out_unlock:
1584         rcu_read_unlock();
1585 out:
1586         return err;
1587 }
1588
1589 SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1590 {
1591         unsigned long ret;
1592         long err;
1593
1594         err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1595         if (err)
1596                 return err;
1597         force_successful_syscall_return();
1598         return (long)ret;
1599 }
1600
1601 #ifdef CONFIG_COMPAT
1602
1603 #ifndef COMPAT_SHMLBA
1604 #define COMPAT_SHMLBA   SHMLBA
1605 #endif
1606
1607 COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
1608 {
1609         unsigned long ret;
1610         long err;
1611
1612         err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
1613         if (err)
1614                 return err;
1615         force_successful_syscall_return();
1616         return (long)ret;
1617 }
1618 #endif
1619
1620 /*
1621  * detach and kill segment if marked destroyed.
1622  * The work is done in shm_close.
1623  */
1624 long ksys_shmdt(char __user *shmaddr)
1625 {
1626         struct mm_struct *mm = current->mm;
1627         struct vm_area_struct *vma;
1628         unsigned long addr = (unsigned long)shmaddr;
1629         int retval = -EINVAL;
1630 #ifdef CONFIG_MMU
1631         loff_t size = 0;
1632         struct file *file;
1633         struct vm_area_struct *next;
1634 #endif
1635
1636         if (addr & ~PAGE_MASK)
1637                 return retval;
1638
1639         if (mmap_write_lock_killable(mm))
1640                 return -EINTR;
1641
1642         /*
1643          * This function tries to be smart and unmap shm segments that
1644          * were modified by partial mlock or munmap calls:
1645          * - It first determines the size of the shm segment that should be
1646          *   unmapped: It searches for a vma that is backed by shm and that
1647          *   started at address shmaddr. It records it's size and then unmaps
1648          *   it.
1649          * - Then it unmaps all shm vmas that started at shmaddr and that
1650          *   are within the initially determined size and that are from the
1651          *   same shm segment from which we determined the size.
1652          * Errors from do_munmap are ignored: the function only fails if
1653          * it's called with invalid parameters or if it's called to unmap
1654          * a part of a vma. Both calls in this function are for full vmas,
1655          * the parameters are directly copied from the vma itself and always
1656          * valid - therefore do_munmap cannot fail. (famous last words?)
1657          */
1658         /*
1659          * If it had been mremap()'d, the starting address would not
1660          * match the usual checks anyway. So assume all vma's are
1661          * above the starting address given.
1662          */
1663         vma = find_vma(mm, addr);
1664
1665 #ifdef CONFIG_MMU
1666         while (vma) {
1667                 next = vma->vm_next;
1668
1669                 /*
1670                  * Check if the starting address would match, i.e. it's
1671                  * a fragment created by mprotect() and/or munmap(), or it
1672                  * otherwise it starts at this address with no hassles.
1673                  */
1674                 if ((vma->vm_ops == &shm_vm_ops) &&
1675                         (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1676
1677                         /*
1678                          * Record the file of the shm segment being
1679                          * unmapped.  With mremap(), someone could place
1680                          * page from another segment but with equal offsets
1681                          * in the range we are unmapping.
1682                          */
1683                         file = vma->vm_file;
1684                         size = i_size_read(file_inode(vma->vm_file));
1685                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1686                         /*
1687                          * We discovered the size of the shm segment, so
1688                          * break out of here and fall through to the next
1689                          * loop that uses the size information to stop
1690                          * searching for matching vma's.
1691                          */
1692                         retval = 0;
1693                         vma = next;
1694                         break;
1695                 }
1696                 vma = next;
1697         }
1698
1699         /*
1700          * We need look no further than the maximum address a fragment
1701          * could possibly have landed at. Also cast things to loff_t to
1702          * prevent overflows and make comparisons vs. equal-width types.
1703          */
1704         size = PAGE_ALIGN(size);
1705         while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1706                 next = vma->vm_next;
1707
1708                 /* finding a matching vma now does not alter retval */
1709                 if ((vma->vm_ops == &shm_vm_ops) &&
1710                     ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
1711                     (vma->vm_file == file))
1712                         do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1713                 vma = next;
1714         }
1715
1716 #else   /* CONFIG_MMU */
1717         /* under NOMMU conditions, the exact address to be destroyed must be
1718          * given
1719          */
1720         if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1721                 do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
1722                 retval = 0;
1723         }
1724
1725 #endif
1726
1727         mmap_write_unlock(mm);
1728         return retval;
1729 }
1730
1731 SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1732 {
1733         return ksys_shmdt(shmaddr);
1734 }
1735
1736 #ifdef CONFIG_PROC_FS
1737 static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1738 {
1739         struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
1740         struct user_namespace *user_ns = seq_user_ns(s);
1741         struct kern_ipc_perm *ipcp = it;
1742         struct shmid_kernel *shp;
1743         unsigned long rss = 0, swp = 0;
1744
1745         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
1746         shm_add_rss_swap(shp, &rss, &swp);
1747
1748 #if BITS_PER_LONG <= 32
1749 #define SIZE_SPEC "%10lu"
1750 #else
1751 #define SIZE_SPEC "%21lu"
1752 #endif
1753
1754         seq_printf(s,
1755                    "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1756                    "%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
1757                    SIZE_SPEC " " SIZE_SPEC "\n",
1758                    shp->shm_perm.key,
1759                    shp->shm_perm.id,
1760                    shp->shm_perm.mode,
1761                    shp->shm_segsz,
1762                    pid_nr_ns(shp->shm_cprid, pid_ns),
1763                    pid_nr_ns(shp->shm_lprid, pid_ns),
1764                    shp->shm_nattch,
1765                    from_kuid_munged(user_ns, shp->shm_perm.uid),
1766                    from_kgid_munged(user_ns, shp->shm_perm.gid),
1767                    from_kuid_munged(user_ns, shp->shm_perm.cuid),
1768                    from_kgid_munged(user_ns, shp->shm_perm.cgid),
1769                    shp->shm_atim,
1770                    shp->shm_dtim,
1771                    shp->shm_ctim,
1772                    rss * PAGE_SIZE,
1773                    swp * PAGE_SIZE);
1774
1775         return 0;
1776 }
1777 #endif