ipc/shm.c

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