linux/ipc/shm.c
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   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 <asm/uaccess.h>
  47
  48#include "util.h"
  49
  50struct 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
  59static const struct file_operations shm_file_operations;
  60static 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
  67static int newseg(struct ipc_namespace *, struct ipc_params *);
  68static void shm_open(struct vm_area_struct *vma);
  69static void shm_close(struct vm_area_struct *vma);
  70static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
  71#ifdef CONFIG_PROC_FS
  72static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  73#endif
  74
  75void 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        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 */
  89static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
  90{
  91        struct shmid_kernel *shp;
  92        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
  93
  94        if (shp->shm_nattch){
  95                shp->shm_perm.mode |= SHM_DEST;
  96                /* Do not find it any more */
  97                shp->shm_perm.key = IPC_PRIVATE;
  98                shm_unlock(shp);
  99        } else
 100                shm_destroy(ns, shp);
 101}
 102
 103#ifdef CONFIG_IPC_NS
 104void shm_exit_ns(struct ipc_namespace *ns)
 105{
 106        free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 107        idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 108}
 109#endif
 110
 111static int __init ipc_ns_init(void)
 112{
 113        shm_init_ns(&init_ipc_ns);
 114        return 0;
 115}
 116
 117pure_initcall(ipc_ns_init);
 118
 119void __init shm_init (void)
 120{
 121        ipc_init_proc_interface("sysvipc/shm",
 122#if BITS_PER_LONG <= 32
 123                                "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 124#else
 125                                "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 126#endif
 127                                IPC_SHM_IDS, sysvipc_shm_proc_show);
 128}
 129
 130static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
 131{
 132        struct kern_ipc_perm *ipcp = ipc_obtain_object(&shm_ids(ns), id);
 133
 134        if (IS_ERR(ipcp))
 135                return ERR_CAST(ipcp);
 136
 137        return container_of(ipcp, struct shmid_kernel, shm_perm);
 138}
 139
 140static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
 141{
 142        struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
 143
 144        if (IS_ERR(ipcp))
 145                return ERR_CAST(ipcp);
 146
 147        return container_of(ipcp, struct shmid_kernel, shm_perm);
 148}
 149
 150/*
 151 * shm_lock_(check_) routines are called in the paths where the rwsem
 152 * is not necessarily held.
 153 */
 154static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 155{
 156        struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 157
 158        if (IS_ERR(ipcp))
 159                return (struct shmid_kernel *)ipcp;
 160
 161        return container_of(ipcp, struct shmid_kernel, shm_perm);
 162}
 163
 164static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 165{
 166        rcu_read_lock();
 167        ipc_lock_object(&ipcp->shm_perm);
 168}
 169
 170static void shm_rcu_free(struct rcu_head *head)
 171{
 172        struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
 173        struct shmid_kernel *shp = ipc_rcu_to_struct(p);
 174
 175        security_shm_free(shp);
 176        ipc_rcu_free(head);
 177}
 178
 179static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 180{
 181        ipc_rmid(&shm_ids(ns), &s->shm_perm);
 182}
 183
 184
 185/* This is called by fork, once for every shm attach. */
 186static void shm_open(struct vm_area_struct *vma)
 187{
 188        struct file *file = vma->vm_file;
 189        struct shm_file_data *sfd = shm_file_data(file);
 190        struct shmid_kernel *shp;
 191
 192        shp = shm_lock(sfd->ns, sfd->id);
 193        BUG_ON(IS_ERR(shp));
 194        shp->shm_atim = get_seconds();
 195        shp->shm_lprid = task_tgid_vnr(current);
 196        shp->shm_nattch++;
 197        shm_unlock(shp);
 198}
 199
 200/*
 201 * shm_destroy - free the struct shmid_kernel
 202 *
 203 * @ns: namespace
 204 * @shp: struct to free
 205 *
 206 * It has to be called with shp and shm_ids.rwsem (writer) locked,
 207 * but returns with shp unlocked and freed.
 208 */
 209static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 210{
 211        ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 212        shm_rmid(ns, shp);
 213        shm_unlock(shp);
 214        if (!is_file_hugepages(shp->shm_file))
 215                shmem_lock(shp->shm_file, 0, shp->mlock_user);
 216        else if (shp->mlock_user)
 217                user_shm_unlock(file_inode(shp->shm_file)->i_size,
 218                                                shp->mlock_user);
 219        fput (shp->shm_file);
 220        ipc_rcu_putref(shp, shm_rcu_free);
 221}
 222
 223/*
 224 * shm_may_destroy - identifies whether shm segment should be destroyed now
 225 *
 226 * Returns true if and only if there are no active users of the segment and
 227 * one of the following is true:
 228 *
 229 * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 230 *
 231 * 2) sysctl kernel.shm_rmid_forced is set to 1.
 232 */
 233static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 234{
 235        return (shp->shm_nattch == 0) &&
 236               (ns->shm_rmid_forced ||
 237                (shp->shm_perm.mode & SHM_DEST));
 238}
 239
 240/*
 241 * remove the attach descriptor vma.
 242 * free memory for segment if it is marked destroyed.
 243 * The descriptor has already been removed from the current->mm->mmap list
 244 * and will later be kfree()d.
 245 */
 246static void shm_close(struct vm_area_struct *vma)
 247{
 248        struct file * file = vma->vm_file;
 249        struct shm_file_data *sfd = shm_file_data(file);
 250        struct shmid_kernel *shp;
 251        struct ipc_namespace *ns = sfd->ns;
 252
 253        down_write(&shm_ids(ns).rwsem);
 254        /* remove from the list of attaches of the shm segment */
 255        shp = shm_lock(ns, sfd->id);
 256        BUG_ON(IS_ERR(shp));
 257        shp->shm_lprid = task_tgid_vnr(current);
 258        shp->shm_dtim = get_seconds();
 259        shp->shm_nattch--;
 260        if (shm_may_destroy(ns, shp))
 261                shm_destroy(ns, shp);
 262        else
 263                shm_unlock(shp);
 264        up_write(&shm_ids(ns).rwsem);
 265}
 266
 267/* Called with ns->shm_ids(ns).rwsem locked */
 268static int shm_try_destroy_current(int id, void *p, void *data)
 269{
 270        struct ipc_namespace *ns = data;
 271        struct kern_ipc_perm *ipcp = p;
 272        struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 273
 274        if (shp->shm_creator != current)
 275                return 0;
 276
 277        /*
 278         * Mark it as orphaned to destroy the segment when
 279         * kernel.shm_rmid_forced is changed.
 280         * It is noop if the following shm_may_destroy() returns true.
 281         */
 282        shp->shm_creator = NULL;
 283
 284        /*
 285         * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
 286         * is not set, it shouldn't be deleted here.
 287         */
 288        if (!ns->shm_rmid_forced)
 289                return 0;
 290
 291        if (shm_may_destroy(ns, shp)) {
 292                shm_lock_by_ptr(shp);
 293                shm_destroy(ns, shp);
 294        }
 295        return 0;
 296}
 297
 298/* Called with ns->shm_ids(ns).rwsem locked */
 299static int shm_try_destroy_orphaned(int id, void *p, void *data)
 300{
 301        struct ipc_namespace *ns = data;
 302        struct kern_ipc_perm *ipcp = p;
 303        struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 304
 305        /*
 306         * We want to destroy segments without users and with already
 307         * exit'ed originating process.
 308         *
 309         * As shp->* are changed under rwsem, it's safe to skip shp locking.
 310         */
 311        if (shp->shm_creator != NULL)
 312                return 0;
 313
 314        if (shm_may_destroy(ns, shp)) {
 315                shm_lock_by_ptr(shp);
 316                shm_destroy(ns, shp);
 317        }
 318        return 0;
 319}
 320
 321void shm_destroy_orphaned(struct ipc_namespace *ns)
 322{
 323        down_write(&shm_ids(ns).rwsem);
 324        if (shm_ids(ns).in_use)
 325                idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 326        up_write(&shm_ids(ns).rwsem);
 327}
 328
 329
 330void exit_shm(struct task_struct *task)
 331{
 332        struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 333
 334        if (shm_ids(ns).in_use == 0)
 335                return;
 336
 337        /* Destroy all already created segments, but not mapped yet */
 338        down_write(&shm_ids(ns).rwsem);
 339        if (shm_ids(ns).in_use)
 340                idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
 341        up_write(&shm_ids(ns).rwsem);
 342}
 343
 344static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 345{
 346        struct file *file = vma->vm_file;
 347        struct shm_file_data *sfd = shm_file_data(file);
 348
 349        return sfd->vm_ops->fault(vma, vmf);
 350}
 351
 352#ifdef CONFIG_NUMA
 353static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 354{
 355        struct file *file = vma->vm_file;
 356        struct shm_file_data *sfd = shm_file_data(file);
 357        int err = 0;
 358        if (sfd->vm_ops->set_policy)
 359                err = sfd->vm_ops->set_policy(vma, new);
 360        return err;
 361}
 362
 363static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 364                                        unsigned long addr)
 365{
 366        struct file *file = vma->vm_file;
 367        struct shm_file_data *sfd = shm_file_data(file);
 368        struct mempolicy *pol = NULL;
 369
 370        if (sfd->vm_ops->get_policy)
 371                pol = sfd->vm_ops->get_policy(vma, addr);
 372        else if (vma->vm_policy)
 373                pol = vma->vm_policy;
 374
 375        return pol;
 376}
 377#endif
 378
 379static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 380{
 381        struct shm_file_data *sfd = shm_file_data(file);
 382        int ret;
 383
 384        ret = sfd->file->f_op->mmap(sfd->file, vma);
 385        if (ret != 0)
 386                return ret;
 387        sfd->vm_ops = vma->vm_ops;
 388#ifdef CONFIG_MMU
 389        BUG_ON(!sfd->vm_ops->fault);
 390#endif
 391        vma->vm_ops = &shm_vm_ops;
 392        shm_open(vma);
 393
 394        return ret;
 395}
 396
 397static int shm_release(struct inode *ino, struct file *file)
 398{
 399        struct shm_file_data *sfd = shm_file_data(file);
 400
 401        put_ipc_ns(sfd->ns);
 402        shm_file_data(file) = NULL;
 403        kfree(sfd);
 404        return 0;
 405}
 406
 407static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 408{
 409        struct shm_file_data *sfd = shm_file_data(file);
 410
 411        if (!sfd->file->f_op->fsync)
 412                return -EINVAL;
 413        return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 414}
 415
 416static long shm_fallocate(struct file *file, int mode, loff_t offset,
 417                          loff_t len)
 418{
 419        struct shm_file_data *sfd = shm_file_data(file);
 420
 421        if (!sfd->file->f_op->fallocate)
 422                return -EOPNOTSUPP;
 423        return sfd->file->f_op->fallocate(file, mode, offset, len);
 424}
 425
 426static unsigned long shm_get_unmapped_area(struct file *file,
 427        unsigned long addr, unsigned long len, unsigned long pgoff,
 428        unsigned long flags)
 429{
 430        struct shm_file_data *sfd = shm_file_data(file);
 431        return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 432                                                pgoff, flags);
 433}
 434
 435static const struct file_operations shm_file_operations = {
 436        .mmap           = shm_mmap,
 437        .fsync          = shm_fsync,
 438        .release        = shm_release,
 439#ifndef CONFIG_MMU
 440        .get_unmapped_area      = shm_get_unmapped_area,
 441#endif
 442        .llseek         = noop_llseek,
 443        .fallocate      = shm_fallocate,
 444};
 445
 446static const struct file_operations shm_file_operations_huge = {
 447        .mmap           = shm_mmap,
 448        .fsync          = shm_fsync,
 449        .release        = shm_release,
 450        .get_unmapped_area      = shm_get_unmapped_area,
 451        .llseek         = noop_llseek,
 452        .fallocate      = shm_fallocate,
 453};
 454
 455int is_file_shm_hugepages(struct file *file)
 456{
 457        return file->f_op == &shm_file_operations_huge;
 458}
 459
 460static const struct vm_operations_struct shm_vm_ops = {
 461        .open   = shm_open,     /* callback for a new vm-area open */
 462        .close  = shm_close,    /* callback for when the vm-area is released */
 463        .fault  = shm_fault,
 464#if defined(CONFIG_NUMA)
 465        .set_policy = shm_set_policy,
 466        .get_policy = shm_get_policy,
 467#endif
 468};
 469
 470/**
 471 * newseg - Create a new shared memory segment
 472 * @ns: namespace
 473 * @params: ptr to the structure that contains key, size and shmflg
 474 *
 475 * Called with shm_ids.rwsem held as a writer.
 476 */
 477
 478static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 479{
 480        key_t key = params->key;
 481        int shmflg = params->flg;
 482        size_t size = params->u.size;
 483        int error;
 484        struct shmid_kernel *shp;
 485        size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 486        struct file * file;
 487        char name[13];
 488        int id;
 489        vm_flags_t acctflag = 0;
 490
 491        if (size < SHMMIN || size > ns->shm_ctlmax)
 492                return -EINVAL;
 493
 494        if (ns->shm_tot + numpages > ns->shm_ctlall)
 495                return -ENOSPC;
 496
 497        shp = ipc_rcu_alloc(sizeof(*shp));
 498        if (!shp)
 499                return -ENOMEM;
 500
 501        shp->shm_perm.key = key;
 502        shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 503        shp->mlock_user = NULL;
 504
 505        shp->shm_perm.security = NULL;
 506        error = security_shm_alloc(shp);
 507        if (error) {
 508                ipc_rcu_putref(shp, ipc_rcu_free);
 509                return error;
 510        }
 511
 512        sprintf (name, "SYSV%08x", key);
 513        if (shmflg & SHM_HUGETLB) {
 514                struct hstate *hs;
 515                size_t hugesize;
 516
 517                hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 518                if (!hs) {
 519                        error = -EINVAL;
 520                        goto no_file;
 521                }
 522                hugesize = ALIGN(size, huge_page_size(hs));
 523
 524                /* hugetlb_file_setup applies strict accounting */
 525                if (shmflg & SHM_NORESERVE)
 526                        acctflag = VM_NORESERVE;
 527                file = hugetlb_file_setup(name, hugesize, acctflag,
 528                                  &shp->mlock_user, HUGETLB_SHMFS_INODE,
 529                                (shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
 530        } else {
 531                /*
 532                 * Do not allow no accounting for OVERCOMMIT_NEVER, even
 533                 * if it's asked for.
 534                 */
 535                if  ((shmflg & SHM_NORESERVE) &&
 536                                sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 537                        acctflag = VM_NORESERVE;
 538                file = shmem_file_setup(name, size, acctflag);
 539        }
 540        error = PTR_ERR(file);
 541        if (IS_ERR(file))
 542                goto no_file;
 543
 544        id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 545        if (id < 0) {
 546                error = id;
 547                goto no_id;
 548        }
 549
 550        shp->shm_cprid = task_tgid_vnr(current);
 551        shp->shm_lprid = 0;
 552        shp->shm_atim = shp->shm_dtim = 0;
 553        shp->shm_ctim = get_seconds();
 554        shp->shm_segsz = size;
 555        shp->shm_nattch = 0;
 556        shp->shm_file = file;
 557        shp->shm_creator = current;
 558
 559        /*
 560         * shmid gets reported as "inode#" in /proc/pid/maps.
 561         * proc-ps tools use this. Changing this will break them.
 562         */
 563        file_inode(file)->i_ino = shp->shm_perm.id;
 564
 565        ns->shm_tot += numpages;
 566        error = shp->shm_perm.id;
 567
 568        ipc_unlock_object(&shp->shm_perm);
 569        rcu_read_unlock();
 570        return error;
 571
 572no_id:
 573        if (is_file_hugepages(file) && shp->mlock_user)
 574                user_shm_unlock(size, shp->mlock_user);
 575        fput(file);
 576no_file:
 577        ipc_rcu_putref(shp, shm_rcu_free);
 578        return error;
 579}
 580
 581/*
 582 * Called with shm_ids.rwsem and ipcp locked.
 583 */
 584static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 585{
 586        struct shmid_kernel *shp;
 587
 588        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 589        return security_shm_associate(shp, shmflg);
 590}
 591
 592/*
 593 * Called with shm_ids.rwsem and ipcp locked.
 594 */
 595static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 596                                struct ipc_params *params)
 597{
 598        struct shmid_kernel *shp;
 599
 600        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 601        if (shp->shm_segsz < params->u.size)
 602                return -EINVAL;
 603
 604        return 0;
 605}
 606
 607SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 608{
 609        struct ipc_namespace *ns;
 610        struct ipc_ops shm_ops;
 611        struct ipc_params shm_params;
 612
 613        ns = current->nsproxy->ipc_ns;
 614
 615        shm_ops.getnew = newseg;
 616        shm_ops.associate = shm_security;
 617        shm_ops.more_checks = shm_more_checks;
 618
 619        shm_params.key = key;
 620        shm_params.flg = shmflg;
 621        shm_params.u.size = size;
 622
 623        return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 624}
 625
 626static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 627{
 628        switch(version) {
 629        case IPC_64:
 630                return copy_to_user(buf, in, sizeof(*in));
 631        case IPC_OLD:
 632            {
 633                struct shmid_ds out;
 634
 635                memset(&out, 0, sizeof(out));
 636                ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 637                out.shm_segsz   = in->shm_segsz;
 638                out.shm_atime   = in->shm_atime;
 639                out.shm_dtime   = in->shm_dtime;
 640                out.shm_ctime   = in->shm_ctime;
 641                out.shm_cpid    = in->shm_cpid;
 642                out.shm_lpid    = in->shm_lpid;
 643                out.shm_nattch  = in->shm_nattch;
 644
 645                return copy_to_user(buf, &out, sizeof(out));
 646            }
 647        default:
 648                return -EINVAL;
 649        }
 650}
 651
 652static inline unsigned long
 653copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 654{
 655        switch(version) {
 656        case IPC_64:
 657                if (copy_from_user(out, buf, sizeof(*out)))
 658                        return -EFAULT;
 659                return 0;
 660        case IPC_OLD:
 661            {
 662                struct shmid_ds tbuf_old;
 663
 664                if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 665                        return -EFAULT;
 666
 667                out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 668                out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 669                out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 670
 671                return 0;
 672            }
 673        default:
 674                return -EINVAL;
 675        }
 676}
 677
 678static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 679{
 680        switch(version) {
 681        case IPC_64:
 682                return copy_to_user(buf, in, sizeof(*in));
 683        case IPC_OLD:
 684            {
 685                struct shminfo out;
 686
 687                if(in->shmmax > INT_MAX)
 688                        out.shmmax = INT_MAX;
 689                else
 690                        out.shmmax = (int)in->shmmax;
 691
 692                out.shmmin      = in->shmmin;
 693                out.shmmni      = in->shmmni;
 694                out.shmseg      = in->shmseg;
 695                out.shmall      = in->shmall; 
 696
 697                return copy_to_user(buf, &out, sizeof(out));
 698            }
 699        default:
 700                return -EINVAL;
 701        }
 702}
 703
 704/*
 705 * Calculate and add used RSS and swap pages of a shm.
 706 * Called with shm_ids.rwsem held as a reader
 707 */
 708static void shm_add_rss_swap(struct shmid_kernel *shp,
 709        unsigned long *rss_add, unsigned long *swp_add)
 710{
 711        struct inode *inode;
 712
 713        inode = file_inode(shp->shm_file);
 714
 715        if (is_file_hugepages(shp->shm_file)) {
 716                struct address_space *mapping = inode->i_mapping;
 717                struct hstate *h = hstate_file(shp->shm_file);
 718                *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 719        } else {
 720#ifdef CONFIG_SHMEM
 721                struct shmem_inode_info *info = SHMEM_I(inode);
 722                spin_lock(&info->lock);
 723                *rss_add += inode->i_mapping->nrpages;
 724                *swp_add += info->swapped;
 725                spin_unlock(&info->lock);
 726#else
 727                *rss_add += inode->i_mapping->nrpages;
 728#endif
 729        }
 730}
 731
 732/*
 733 * Called with shm_ids.rwsem held as a reader
 734 */
 735static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 736                unsigned long *swp)
 737{
 738        int next_id;
 739        int total, in_use;
 740
 741        *rss = 0;
 742        *swp = 0;
 743
 744        in_use = shm_ids(ns).in_use;
 745
 746        for (total = 0, next_id = 0; total < in_use; next_id++) {
 747                struct kern_ipc_perm *ipc;
 748                struct shmid_kernel *shp;
 749
 750                ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 751                if (ipc == NULL)
 752                        continue;
 753                shp = container_of(ipc, struct shmid_kernel, shm_perm);
 754
 755                shm_add_rss_swap(shp, rss, swp);
 756
 757                total++;
 758        }
 759}
 760
 761/*
 762 * This function handles some shmctl commands which require the rwsem
 763 * to be held in write mode.
 764 * NOTE: no locks must be held, the rwsem is taken inside this function.
 765 */
 766static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 767                       struct shmid_ds __user *buf, int version)
 768{
 769        struct kern_ipc_perm *ipcp;
 770        struct shmid64_ds shmid64;
 771        struct shmid_kernel *shp;
 772        int err;
 773
 774        if (cmd == IPC_SET) {
 775                if (copy_shmid_from_user(&shmid64, buf, version))
 776                        return -EFAULT;
 777        }
 778
 779        down_write(&shm_ids(ns).rwsem);
 780        rcu_read_lock();
 781
 782        ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
 783                                      &shmid64.shm_perm, 0);
 784        if (IS_ERR(ipcp)) {
 785                err = PTR_ERR(ipcp);
 786                goto out_unlock1;
 787        }
 788
 789        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 790
 791        err = security_shm_shmctl(shp, cmd);
 792        if (err)
 793                goto out_unlock1;
 794
 795        switch (cmd) {
 796        case IPC_RMID:
 797                ipc_lock_object(&shp->shm_perm);
 798                /* do_shm_rmid unlocks the ipc object and rcu */
 799                do_shm_rmid(ns, ipcp);
 800                goto out_up;
 801        case IPC_SET:
 802                ipc_lock_object(&shp->shm_perm);
 803                err = ipc_update_perm(&shmid64.shm_perm, ipcp);
 804                if (err)
 805                        goto out_unlock0;
 806                shp->shm_ctim = get_seconds();
 807                break;
 808        default:
 809                err = -EINVAL;
 810                goto out_unlock1;
 811        }
 812
 813out_unlock0:
 814        ipc_unlock_object(&shp->shm_perm);
 815out_unlock1:
 816        rcu_read_unlock();
 817out_up:
 818        up_write(&shm_ids(ns).rwsem);
 819        return err;
 820}
 821
 822static int shmctl_nolock(struct ipc_namespace *ns, int shmid,
 823                         int cmd, int version, void __user *buf)
 824{
 825        int err;
 826        struct shmid_kernel *shp;
 827
 828        /* preliminary security checks for *_INFO */
 829        if (cmd == IPC_INFO || cmd == SHM_INFO) {
 830                err = security_shm_shmctl(NULL, cmd);
 831                if (err)
 832                        return err;
 833        }
 834
 835        switch (cmd) {
 836        case IPC_INFO:
 837        {
 838                struct shminfo64 shminfo;
 839
 840                memset(&shminfo, 0, sizeof(shminfo));
 841                shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 842                shminfo.shmmax = ns->shm_ctlmax;
 843                shminfo.shmall = ns->shm_ctlall;
 844
 845                shminfo.shmmin = SHMMIN;
 846                if(copy_shminfo_to_user (buf, &shminfo, version))
 847                        return -EFAULT;
 848
 849                down_read(&shm_ids(ns).rwsem);
 850                err = ipc_get_maxid(&shm_ids(ns));
 851                up_read(&shm_ids(ns).rwsem);
 852
 853                if(err<0)
 854                        err = 0;
 855                goto out;
 856        }
 857        case SHM_INFO:
 858        {
 859                struct shm_info shm_info;
 860
 861                memset(&shm_info, 0, sizeof(shm_info));
 862                down_read(&shm_ids(ns).rwsem);
 863                shm_info.used_ids = shm_ids(ns).in_use;
 864                shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 865                shm_info.shm_tot = ns->shm_tot;
 866                shm_info.swap_attempts = 0;
 867                shm_info.swap_successes = 0;
 868                err = ipc_get_maxid(&shm_ids(ns));
 869                up_read(&shm_ids(ns).rwsem);
 870                if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 871                        err = -EFAULT;
 872                        goto out;
 873                }
 874
 875                err = err < 0 ? 0 : err;
 876                goto out;
 877        }
 878        case SHM_STAT:
 879        case IPC_STAT:
 880        {
 881                struct shmid64_ds tbuf;
 882                int result;
 883
 884                rcu_read_lock();
 885                if (cmd == SHM_STAT) {
 886                        shp = shm_obtain_object(ns, shmid);
 887                        if (IS_ERR(shp)) {
 888                                err = PTR_ERR(shp);
 889                                goto out_unlock;
 890                        }
 891                        result = shp->shm_perm.id;
 892                } else {
 893                        shp = shm_obtain_object_check(ns, shmid);
 894                        if (IS_ERR(shp)) {
 895                                err = PTR_ERR(shp);
 896                                goto out_unlock;
 897                        }
 898                        result = 0;
 899                }
 900
 901                err = -EACCES;
 902                if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 903                        goto out_unlock;
 904
 905                err = security_shm_shmctl(shp, cmd);
 906                if (err)
 907                        goto out_unlock;
 908
 909                memset(&tbuf, 0, sizeof(tbuf));
 910                kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 911                tbuf.shm_segsz  = shp->shm_segsz;
 912                tbuf.shm_atime  = shp->shm_atim;
 913                tbuf.shm_dtime  = shp->shm_dtim;
 914                tbuf.shm_ctime  = shp->shm_ctim;
 915                tbuf.shm_cpid   = shp->shm_cprid;
 916                tbuf.shm_lpid   = shp->shm_lprid;
 917                tbuf.shm_nattch = shp->shm_nattch;
 918                rcu_read_unlock();
 919
 920                if (copy_shmid_to_user(buf, &tbuf, version))
 921                        err = -EFAULT;
 922                else
 923                        err = result;
 924                goto out;
 925        }
 926        default:
 927                return -EINVAL;
 928        }
 929
 930out_unlock:
 931        rcu_read_unlock();
 932out:
 933        return err;
 934}
 935
 936SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 937{
 938        struct shmid_kernel *shp;
 939        int err, version;
 940        struct ipc_namespace *ns;
 941
 942        if (cmd < 0 || shmid < 0)
 943                return -EINVAL;
 944
 945        version = ipc_parse_version(&cmd);
 946        ns = current->nsproxy->ipc_ns;
 947
 948        switch (cmd) {
 949        case IPC_INFO:
 950        case SHM_INFO:
 951        case SHM_STAT:
 952        case IPC_STAT:
 953                return shmctl_nolock(ns, shmid, cmd, version, buf);
 954        case IPC_RMID:
 955        case IPC_SET:
 956                return shmctl_down(ns, shmid, cmd, buf, version);
 957        case SHM_LOCK:
 958        case SHM_UNLOCK:
 959        {
 960                struct file *shm_file;
 961
 962                rcu_read_lock();
 963                shp = shm_obtain_object_check(ns, shmid);
 964                if (IS_ERR(shp)) {
 965                        err = PTR_ERR(shp);
 966                        goto out_unlock1;
 967                }
 968
 969                audit_ipc_obj(&(shp->shm_perm));
 970                err = security_shm_shmctl(shp, cmd);
 971                if (err)
 972                        goto out_unlock1;
 973
 974                ipc_lock_object(&shp->shm_perm);
 975                if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
 976                        kuid_t euid = current_euid();
 977                        err = -EPERM;
 978                        if (!uid_eq(euid, shp->shm_perm.uid) &&
 979                            !uid_eq(euid, shp->shm_perm.cuid))
 980                                goto out_unlock0;
 981                        if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
 982                                goto out_unlock0;
 983                }
 984
 985                shm_file = shp->shm_file;
 986                if (is_file_hugepages(shm_file))
 987                        goto out_unlock0;
 988
 989                if (cmd == SHM_LOCK) {
 990                        struct user_struct *user = current_user();
 991                        err = shmem_lock(shm_file, 1, user);
 992                        if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
 993                                shp->shm_perm.mode |= SHM_LOCKED;
 994                                shp->mlock_user = user;
 995                        }
 996                        goto out_unlock0;
 997                }
 998
 999                /* SHM_UNLOCK */
1000                if (!(shp->shm_perm.mode & SHM_LOCKED))
1001                        goto out_unlock0;
1002                shmem_lock(shm_file, 0, shp->mlock_user);
1003                shp->shm_perm.mode &= ~SHM_LOCKED;
1004                shp->mlock_user = NULL;
1005                get_file(shm_file);
1006                ipc_unlock_object(&shp->shm_perm);
1007                rcu_read_unlock();
1008                shmem_unlock_mapping(shm_file->f_mapping);
1009
1010                fput(shm_file);
1011                return err;
1012        }
1013        default:
1014                return -EINVAL;
1015        }
1016
1017out_unlock0:
1018        ipc_unlock_object(&shp->shm_perm);
1019out_unlock1:
1020        rcu_read_unlock();
1021        return err;
1022}
1023
1024/*
1025 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
1026 *
1027 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
1028 * "raddr" thing points to kernel space, and there has to be a wrapper around
1029 * this.
1030 */
1031long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
1032              unsigned long shmlba)
1033{
1034        struct shmid_kernel *shp;
1035        unsigned long addr;
1036        unsigned long size;
1037        struct file * file;
1038        int    err;
1039        unsigned long flags;
1040        unsigned long prot;
1041        int acc_mode;
1042        struct ipc_namespace *ns;
1043        struct shm_file_data *sfd;
1044        struct path path;
1045        fmode_t f_mode;
1046        unsigned long populate = 0;
1047
1048        err = -EINVAL;
1049        if (shmid < 0)
1050                goto out;
1051        else if ((addr = (ulong)shmaddr)) {
1052                if (addr & (shmlba - 1)) {
1053                        if (shmflg & SHM_RND)
1054                                addr &= ~(shmlba - 1);     /* round down */
1055                        else
1056#ifndef __ARCH_FORCE_SHMLBA
1057                                if (addr & ~PAGE_MASK)
1058#endif
1059                                        goto out;
1060                }
1061                flags = MAP_SHARED | MAP_FIXED;
1062        } else {
1063                if ((shmflg & SHM_REMAP))
1064                        goto out;
1065
1066                flags = MAP_SHARED;
1067        }
1068
1069        if (shmflg & SHM_RDONLY) {
1070                prot = PROT_READ;
1071                acc_mode = S_IRUGO;
1072                f_mode = FMODE_READ;
1073        } else {
1074                prot = PROT_READ | PROT_WRITE;
1075                acc_mode = S_IRUGO | S_IWUGO;
1076                f_mode = FMODE_READ | FMODE_WRITE;
1077        }
1078        if (shmflg & SHM_EXEC) {
1079                prot |= PROT_EXEC;
1080                acc_mode |= S_IXUGO;
1081        }
1082
1083        /*
1084         * We cannot rely on the fs check since SYSV IPC does have an
1085         * additional creator id...
1086         */
1087        ns = current->nsproxy->ipc_ns;
1088        rcu_read_lock();
1089        shp = shm_obtain_object_check(ns, shmid);
1090        if (IS_ERR(shp)) {
1091                err = PTR_ERR(shp);
1092                goto out_unlock;
1093        }
1094
1095        err = -EACCES;
1096        if (ipcperms(ns, &shp->shm_perm, acc_mode))
1097                goto out_unlock;
1098
1099        err = security_shm_shmat(shp, shmaddr, shmflg);
1100        if (err)
1101                goto out_unlock;
1102
1103        ipc_lock_object(&shp->shm_perm);
1104        path = shp->shm_file->f_path;
1105        path_get(&path);
1106        shp->shm_nattch++;
1107        size = i_size_read(path.dentry->d_inode);
1108        ipc_unlock_object(&shp->shm_perm);
1109        rcu_read_unlock();
1110
1111        err = -ENOMEM;
1112        sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1113        if (!sfd) {
1114                path_put(&path);
1115                goto out_nattch;
1116        }
1117
1118        file = alloc_file(&path, f_mode,
1119                          is_file_hugepages(shp->shm_file) ?
1120                                &shm_file_operations_huge :
1121                                &shm_file_operations);
1122        err = PTR_ERR(file);
1123        if (IS_ERR(file)) {
1124                kfree(sfd);
1125                path_put(&path);
1126                goto out_nattch;
1127        }
1128
1129        file->private_data = sfd;
1130        file->f_mapping = shp->shm_file->f_mapping;
1131        sfd->id = shp->shm_perm.id;
1132        sfd->ns = get_ipc_ns(ns);
1133        sfd->file = shp->shm_file;
1134        sfd->vm_ops = NULL;
1135
1136        err = security_mmap_file(file, prot, flags);
1137        if (err)
1138                goto out_fput;
1139
1140        down_write(&current->mm->mmap_sem);
1141        if (addr && !(shmflg & SHM_REMAP)) {
1142                err = -EINVAL;
1143                if (find_vma_intersection(current->mm, addr, addr + size))
1144                        goto invalid;
1145                /*
1146                 * If shm segment goes below stack, make sure there is some
1147                 * space left for the stack to grow (at least 4 pages).
1148                 */
1149                if (addr < current->mm->start_stack &&
1150                    addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1151                        goto invalid;
1152        }
1153
1154        addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate);
1155        *raddr = addr;
1156        err = 0;
1157        if (IS_ERR_VALUE(addr))
1158                err = (long)addr;
1159invalid:
1160        up_write(&current->mm->mmap_sem);
1161        if (populate)
1162                mm_populate(addr, populate);
1163
1164out_fput:
1165        fput(file);
1166
1167out_nattch:
1168        down_write(&shm_ids(ns).rwsem);
1169        shp = shm_lock(ns, shmid);
1170        BUG_ON(IS_ERR(shp));
1171        shp->shm_nattch--;
1172        if (shm_may_destroy(ns, shp))
1173                shm_destroy(ns, shp);
1174        else
1175                shm_unlock(shp);
1176        up_write(&shm_ids(ns).rwsem);
1177        return err;
1178
1179out_unlock:
1180        rcu_read_unlock();
1181out:
1182        return err;
1183}
1184
1185SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1186{
1187        unsigned long ret;
1188        long err;
1189
1190        err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
1191        if (err)
1192                return err;
1193        force_successful_syscall_return();
1194        return (long)ret;
1195}
1196
1197/*
1198 * detach and kill segment if marked destroyed.
1199 * The work is done in shm_close.
1200 */
1201SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1202{
1203        struct mm_struct *mm = current->mm;
1204        struct vm_area_struct *vma;
1205        unsigned long addr = (unsigned long)shmaddr;
1206        int retval = -EINVAL;
1207#ifdef CONFIG_MMU
1208        loff_t size = 0;
1209        struct vm_area_struct *next;
1210#endif
1211
1212        if (addr & ~PAGE_MASK)
1213                return retval;
1214
1215        down_write(&mm->mmap_sem);
1216
1217        /*
1218         * This function tries to be smart and unmap shm segments that
1219         * were modified by partial mlock or munmap calls:
1220         * - It first determines the size of the shm segment that should be
1221         *   unmapped: It searches for a vma that is backed by shm and that
1222         *   started at address shmaddr. It records it's size and then unmaps
1223         *   it.
1224         * - Then it unmaps all shm vmas that started at shmaddr and that
1225         *   are within the initially determined size.
1226         * Errors from do_munmap are ignored: the function only fails if
1227         * it's called with invalid parameters or if it's called to unmap
1228         * a part of a vma. Both calls in this function are for full vmas,
1229         * the parameters are directly copied from the vma itself and always
1230         * valid - therefore do_munmap cannot fail. (famous last words?)
1231         */
1232        /*
1233         * If it had been mremap()'d, the starting address would not
1234         * match the usual checks anyway. So assume all vma's are
1235         * above the starting address given.
1236         */
1237        vma = find_vma(mm, addr);
1238
1239#ifdef CONFIG_MMU
1240        while (vma) {
1241                next = vma->vm_next;
1242
1243                /*
1244                 * Check if the starting address would match, i.e. it's
1245                 * a fragment created by mprotect() and/or munmap(), or it
1246                 * otherwise it starts at this address with no hassles.
1247                 */
1248                if ((vma->vm_ops == &shm_vm_ops) &&
1249                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1250
1251
1252                        size = file_inode(vma->vm_file)->i_size;
1253                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1254                        /*
1255                         * We discovered the size of the shm segment, so
1256                         * break out of here and fall through to the next
1257                         * loop that uses the size information to stop
1258                         * searching for matching vma's.
1259                         */
1260                        retval = 0;
1261                        vma = next;
1262                        break;
1263                }
1264                vma = next;
1265        }
1266
1267        /*
1268         * We need look no further than the maximum address a fragment
1269         * could possibly have landed at. Also cast things to loff_t to
1270         * prevent overflows and make comparisons vs. equal-width types.
1271         */
1272        size = PAGE_ALIGN(size);
1273        while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1274                next = vma->vm_next;
1275
1276                /* finding a matching vma now does not alter retval */
1277                if ((vma->vm_ops == &shm_vm_ops) &&
1278                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1279
1280                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1281                vma = next;
1282        }
1283
1284#else /* CONFIG_MMU */
1285        /* under NOMMU conditions, the exact address to be destroyed must be
1286         * given */
1287        if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1288                do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1289                retval = 0;
1290        }
1291
1292#endif
1293
1294        up_write(&mm->mmap_sem);
1295        return retval;
1296}
1297
1298#ifdef CONFIG_PROC_FS
1299static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1300{
1301        struct user_namespace *user_ns = seq_user_ns(s);
1302        struct shmid_kernel *shp = it;
1303        unsigned long rss = 0, swp = 0;
1304
1305        shm_add_rss_swap(shp, &rss, &swp);
1306
1307#if BITS_PER_LONG <= 32
1308#define SIZE_SPEC "%10lu"
1309#else
1310#define SIZE_SPEC "%21lu"
1311#endif
1312
1313        return seq_printf(s,
1314                          "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1315                          "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1316                          SIZE_SPEC " " SIZE_SPEC "\n",
1317                          shp->shm_perm.key,
1318                          shp->shm_perm.id,
1319                          shp->shm_perm.mode,
1320                          shp->shm_segsz,
1321                          shp->shm_cprid,
1322                          shp->shm_lprid,
1323                          shp->shm_nattch,
1324                          from_kuid_munged(user_ns, shp->shm_perm.uid),
1325                          from_kgid_munged(user_ns, shp->shm_perm.gid),
1326                          from_kuid_munged(user_ns, shp->shm_perm.cuid),
1327                          from_kgid_munged(user_ns, shp->shm_perm.cgid),
1328                          shp->shm_atim,
1329                          shp->shm_dtim,
1330                          shp->shm_ctim,
1331                          rss * PAGE_SIZE,
1332                          swp * PAGE_SIZE);
1333}
1334#endif
1335
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