linux/ipc/shm.c
<<
>>
Prefs
   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
  24#include <linux/slab.h>
  25#include <linux/mm.h>
  26#include <linux/hugetlb.h>
  27#include <linux/shm.h>
  28#include <linux/init.h>
  29#include <linux/file.h>
  30#include <linux/mman.h>
  31#include <linux/shmem_fs.h>
  32#include <linux/security.h>
  33#include <linux/syscalls.h>
  34#include <linux/audit.h>
  35#include <linux/capability.h>
  36#include <linux/ptrace.h>
  37#include <linux/seq_file.h>
  38#include <linux/rwsem.h>
  39#include <linux/nsproxy.h>
  40#include <linux/mount.h>
  41#include <linux/ipc_namespace.h>
  42
  43#include <asm/uaccess.h>
  44
  45#include "util.h"
  46
  47struct shm_file_data {
  48        int id;
  49        struct ipc_namespace *ns;
  50        struct file *file;
  51        const struct vm_operations_struct *vm_ops;
  52};
  53
  54#define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  55
  56static const struct file_operations shm_file_operations;
  57static const struct vm_operations_struct shm_vm_ops;
  58
  59#define shm_ids(ns)     ((ns)->ids[IPC_SHM_IDS])
  60
  61#define shm_unlock(shp)                 \
  62        ipc_unlock(&(shp)->shm_perm)
  63
  64static int newseg(struct ipc_namespace *, struct ipc_params *);
  65static void shm_open(struct vm_area_struct *vma);
  66static void shm_close(struct vm_area_struct *vma);
  67static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
  68#ifdef CONFIG_PROC_FS
  69static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  70#endif
  71
  72void shm_init_ns(struct ipc_namespace *ns)
  73{
  74        ns->shm_ctlmax = SHMMAX;
  75        ns->shm_ctlall = SHMALL;
  76        ns->shm_ctlmni = SHMMNI;
  77        ns->shm_tot = 0;
  78        ipc_init_ids(&shm_ids(ns));
  79}
  80
  81/*
  82 * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
  83 * Only shm_ids.rw_mutex remains locked on exit.
  84 */
  85static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
  86{
  87        struct shmid_kernel *shp;
  88        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
  89
  90        if (shp->shm_nattch){
  91                shp->shm_perm.mode |= SHM_DEST;
  92                /* Do not find it any more */
  93                shp->shm_perm.key = IPC_PRIVATE;
  94                shm_unlock(shp);
  95        } else
  96                shm_destroy(ns, shp);
  97}
  98
  99#ifdef CONFIG_IPC_NS
 100void shm_exit_ns(struct ipc_namespace *ns)
 101{
 102        free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 103        idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 104}
 105#endif
 106
 107void __init shm_init (void)
 108{
 109        shm_init_ns(&init_ipc_ns);
 110        ipc_init_proc_interface("sysvipc/shm",
 111                                "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
 112                                IPC_SHM_IDS, sysvipc_shm_proc_show);
 113}
 114
 115/*
 116 * shm_lock_(check_) routines are called in the paths where the rw_mutex
 117 * is not necessarily held.
 118 */
 119static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 120{
 121        struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 122
 123        if (IS_ERR(ipcp))
 124                return (struct shmid_kernel *)ipcp;
 125
 126        return container_of(ipcp, struct shmid_kernel, shm_perm);
 127}
 128
 129static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
 130                                                int id)
 131{
 132        struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
 133
 134        if (IS_ERR(ipcp))
 135                return (struct shmid_kernel *)ipcp;
 136
 137        return container_of(ipcp, struct shmid_kernel, shm_perm);
 138}
 139
 140static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 141{
 142        ipc_rmid(&shm_ids(ns), &s->shm_perm);
 143}
 144
 145
 146/* This is called by fork, once for every shm attach. */
 147static void shm_open(struct vm_area_struct *vma)
 148{
 149        struct file *file = vma->vm_file;
 150        struct shm_file_data *sfd = shm_file_data(file);
 151        struct shmid_kernel *shp;
 152
 153        shp = shm_lock(sfd->ns, sfd->id);
 154        BUG_ON(IS_ERR(shp));
 155        shp->shm_atim = get_seconds();
 156        shp->shm_lprid = task_tgid_vnr(current);
 157        shp->shm_nattch++;
 158        shm_unlock(shp);
 159}
 160
 161/*
 162 * shm_destroy - free the struct shmid_kernel
 163 *
 164 * @ns: namespace
 165 * @shp: struct to free
 166 *
 167 * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
 168 * but returns with shp unlocked and freed.
 169 */
 170static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 171{
 172        ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 173        shm_rmid(ns, shp);
 174        shm_unlock(shp);
 175        if (!is_file_hugepages(shp->shm_file))
 176                shmem_lock(shp->shm_file, 0, shp->mlock_user);
 177        else if (shp->mlock_user)
 178                user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
 179                                                shp->mlock_user);
 180        fput (shp->shm_file);
 181        security_shm_free(shp);
 182        ipc_rcu_putref(shp);
 183}
 184
 185/*
 186 * remove the attach descriptor vma.
 187 * free memory for segment if it is marked destroyed.
 188 * The descriptor has already been removed from the current->mm->mmap list
 189 * and will later be kfree()d.
 190 */
 191static void shm_close(struct vm_area_struct *vma)
 192{
 193        struct file * file = vma->vm_file;
 194        struct shm_file_data *sfd = shm_file_data(file);
 195        struct shmid_kernel *shp;
 196        struct ipc_namespace *ns = sfd->ns;
 197
 198        down_write(&shm_ids(ns).rw_mutex);
 199        /* remove from the list of attaches of the shm segment */
 200        shp = shm_lock(ns, sfd->id);
 201        BUG_ON(IS_ERR(shp));
 202        shp->shm_lprid = task_tgid_vnr(current);
 203        shp->shm_dtim = get_seconds();
 204        shp->shm_nattch--;
 205        if(shp->shm_nattch == 0 &&
 206           shp->shm_perm.mode & SHM_DEST)
 207                shm_destroy(ns, shp);
 208        else
 209                shm_unlock(shp);
 210        up_write(&shm_ids(ns).rw_mutex);
 211}
 212
 213static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 214{
 215        struct file *file = vma->vm_file;
 216        struct shm_file_data *sfd = shm_file_data(file);
 217
 218        return sfd->vm_ops->fault(vma, vmf);
 219}
 220
 221#ifdef CONFIG_NUMA
 222static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 223{
 224        struct file *file = vma->vm_file;
 225        struct shm_file_data *sfd = shm_file_data(file);
 226        int err = 0;
 227        if (sfd->vm_ops->set_policy)
 228                err = sfd->vm_ops->set_policy(vma, new);
 229        return err;
 230}
 231
 232static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 233                                        unsigned long addr)
 234{
 235        struct file *file = vma->vm_file;
 236        struct shm_file_data *sfd = shm_file_data(file);
 237        struct mempolicy *pol = NULL;
 238
 239        if (sfd->vm_ops->get_policy)
 240                pol = sfd->vm_ops->get_policy(vma, addr);
 241        else if (vma->vm_policy)
 242                pol = vma->vm_policy;
 243
 244        return pol;
 245}
 246#endif
 247
 248static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 249{
 250        struct shm_file_data *sfd = shm_file_data(file);
 251        int ret;
 252
 253        ret = sfd->file->f_op->mmap(sfd->file, vma);
 254        if (ret != 0)
 255                return ret;
 256        sfd->vm_ops = vma->vm_ops;
 257#ifdef CONFIG_MMU
 258        BUG_ON(!sfd->vm_ops->fault);
 259#endif
 260        vma->vm_ops = &shm_vm_ops;
 261        shm_open(vma);
 262
 263        return ret;
 264}
 265
 266static int shm_release(struct inode *ino, struct file *file)
 267{
 268        struct shm_file_data *sfd = shm_file_data(file);
 269
 270        put_ipc_ns(sfd->ns);
 271        shm_file_data(file) = NULL;
 272        kfree(sfd);
 273        return 0;
 274}
 275
 276static int shm_fsync(struct file *file, int datasync)
 277{
 278        struct shm_file_data *sfd = shm_file_data(file);
 279
 280        if (!sfd->file->f_op->fsync)
 281                return -EINVAL;
 282        return sfd->file->f_op->fsync(sfd->file, datasync);
 283}
 284
 285static unsigned long shm_get_unmapped_area(struct file *file,
 286        unsigned long addr, unsigned long len, unsigned long pgoff,
 287        unsigned long flags)
 288{
 289        struct shm_file_data *sfd = shm_file_data(file);
 290        return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 291                                                pgoff, flags);
 292}
 293
 294static const struct file_operations shm_file_operations = {
 295        .mmap           = shm_mmap,
 296        .fsync          = shm_fsync,
 297        .release        = shm_release,
 298#ifndef CONFIG_MMU
 299        .get_unmapped_area      = shm_get_unmapped_area,
 300#endif
 301};
 302
 303static const struct file_operations shm_file_operations_huge = {
 304        .mmap           = shm_mmap,
 305        .fsync          = shm_fsync,
 306        .release        = shm_release,
 307        .get_unmapped_area      = shm_get_unmapped_area,
 308};
 309
 310int is_file_shm_hugepages(struct file *file)
 311{
 312        return file->f_op == &shm_file_operations_huge;
 313}
 314
 315static const struct vm_operations_struct shm_vm_ops = {
 316        .open   = shm_open,     /* callback for a new vm-area open */
 317        .close  = shm_close,    /* callback for when the vm-area is released */
 318        .fault  = shm_fault,
 319#if defined(CONFIG_NUMA)
 320        .set_policy = shm_set_policy,
 321        .get_policy = shm_get_policy,
 322#endif
 323};
 324
 325/**
 326 * newseg - Create a new shared memory segment
 327 * @ns: namespace
 328 * @params: ptr to the structure that contains key, size and shmflg
 329 *
 330 * Called with shm_ids.rw_mutex held as a writer.
 331 */
 332
 333static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 334{
 335        key_t key = params->key;
 336        int shmflg = params->flg;
 337        size_t size = params->u.size;
 338        int error;
 339        struct shmid_kernel *shp;
 340        int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 341        struct file * file;
 342        char name[13];
 343        int id;
 344        int acctflag = 0;
 345
 346        if (size < SHMMIN || size > ns->shm_ctlmax)
 347                return -EINVAL;
 348
 349        if (ns->shm_tot + numpages > ns->shm_ctlall)
 350                return -ENOSPC;
 351
 352        shp = ipc_rcu_alloc(sizeof(*shp));
 353        if (!shp)
 354                return -ENOMEM;
 355
 356        shp->shm_perm.key = key;
 357        shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 358        shp->mlock_user = NULL;
 359
 360        shp->shm_perm.security = NULL;
 361        error = security_shm_alloc(shp);
 362        if (error) {
 363                ipc_rcu_putref(shp);
 364                return error;
 365        }
 366
 367        sprintf (name, "SYSV%08x", key);
 368        if (shmflg & SHM_HUGETLB) {
 369                /* hugetlb_file_setup applies strict accounting */
 370                if (shmflg & SHM_NORESERVE)
 371                        acctflag = VM_NORESERVE;
 372                file = hugetlb_file_setup(name, size, acctflag,
 373                                        &shp->mlock_user, HUGETLB_SHMFS_INODE);
 374        } else {
 375                /*
 376                 * Do not allow no accounting for OVERCOMMIT_NEVER, even
 377                 * if it's asked for.
 378                 */
 379                if  ((shmflg & SHM_NORESERVE) &&
 380                                sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 381                        acctflag = VM_NORESERVE;
 382                file = shmem_file_setup(name, size, acctflag);
 383        }
 384        error = PTR_ERR(file);
 385        if (IS_ERR(file))
 386                goto no_file;
 387
 388        id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 389        if (id < 0) {
 390                error = id;
 391                goto no_id;
 392        }
 393
 394        shp->shm_cprid = task_tgid_vnr(current);
 395        shp->shm_lprid = 0;
 396        shp->shm_atim = shp->shm_dtim = 0;
 397        shp->shm_ctim = get_seconds();
 398        shp->shm_segsz = size;
 399        shp->shm_nattch = 0;
 400        shp->shm_file = file;
 401        /*
 402         * shmid gets reported as "inode#" in /proc/pid/maps.
 403         * proc-ps tools use this. Changing this will break them.
 404         */
 405        file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 406
 407        ns->shm_tot += numpages;
 408        error = shp->shm_perm.id;
 409        shm_unlock(shp);
 410        return error;
 411
 412no_id:
 413        if (is_file_hugepages(file) && shp->mlock_user)
 414                user_shm_unlock(size, shp->mlock_user);
 415        fput(file);
 416no_file:
 417        security_shm_free(shp);
 418        ipc_rcu_putref(shp);
 419        return error;
 420}
 421
 422/*
 423 * Called with shm_ids.rw_mutex and ipcp locked.
 424 */
 425static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 426{
 427        struct shmid_kernel *shp;
 428
 429        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 430        return security_shm_associate(shp, shmflg);
 431}
 432
 433/*
 434 * Called with shm_ids.rw_mutex and ipcp locked.
 435 */
 436static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 437                                struct ipc_params *params)
 438{
 439        struct shmid_kernel *shp;
 440
 441        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 442        if (shp->shm_segsz < params->u.size)
 443                return -EINVAL;
 444
 445        return 0;
 446}
 447
 448SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 449{
 450        struct ipc_namespace *ns;
 451        struct ipc_ops shm_ops;
 452        struct ipc_params shm_params;
 453
 454        ns = current->nsproxy->ipc_ns;
 455
 456        shm_ops.getnew = newseg;
 457        shm_ops.associate = shm_security;
 458        shm_ops.more_checks = shm_more_checks;
 459
 460        shm_params.key = key;
 461        shm_params.flg = shmflg;
 462        shm_params.u.size = size;
 463
 464        return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 465}
 466
 467static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 468{
 469        switch(version) {
 470        case IPC_64:
 471                return copy_to_user(buf, in, sizeof(*in));
 472        case IPC_OLD:
 473            {
 474                struct shmid_ds out;
 475
 476                ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 477                out.shm_segsz   = in->shm_segsz;
 478                out.shm_atime   = in->shm_atime;
 479                out.shm_dtime   = in->shm_dtime;
 480                out.shm_ctime   = in->shm_ctime;
 481                out.shm_cpid    = in->shm_cpid;
 482                out.shm_lpid    = in->shm_lpid;
 483                out.shm_nattch  = in->shm_nattch;
 484
 485                return copy_to_user(buf, &out, sizeof(out));
 486            }
 487        default:
 488                return -EINVAL;
 489        }
 490}
 491
 492static inline unsigned long
 493copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 494{
 495        switch(version) {
 496        case IPC_64:
 497                if (copy_from_user(out, buf, sizeof(*out)))
 498                        return -EFAULT;
 499                return 0;
 500        case IPC_OLD:
 501            {
 502                struct shmid_ds tbuf_old;
 503
 504                if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 505                        return -EFAULT;
 506
 507                out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 508                out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 509                out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 510
 511                return 0;
 512            }
 513        default:
 514                return -EINVAL;
 515        }
 516}
 517
 518static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 519{
 520        switch(version) {
 521        case IPC_64:
 522                return copy_to_user(buf, in, sizeof(*in));
 523        case IPC_OLD:
 524            {
 525                struct shminfo out;
 526
 527                if(in->shmmax > INT_MAX)
 528                        out.shmmax = INT_MAX;
 529                else
 530                        out.shmmax = (int)in->shmmax;
 531
 532                out.shmmin      = in->shmmin;
 533                out.shmmni      = in->shmmni;
 534                out.shmseg      = in->shmseg;
 535                out.shmall      = in->shmall; 
 536
 537                return copy_to_user(buf, &out, sizeof(out));
 538            }
 539        default:
 540                return -EINVAL;
 541        }
 542}
 543
 544/*
 545 * Called with shm_ids.rw_mutex held as a reader
 546 */
 547static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 548                unsigned long *swp)
 549{
 550        int next_id;
 551        int total, in_use;
 552
 553        *rss = 0;
 554        *swp = 0;
 555
 556        in_use = shm_ids(ns).in_use;
 557
 558        for (total = 0, next_id = 0; total < in_use; next_id++) {
 559                struct kern_ipc_perm *ipc;
 560                struct shmid_kernel *shp;
 561                struct inode *inode;
 562
 563                ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 564                if (ipc == NULL)
 565                        continue;
 566                shp = container_of(ipc, struct shmid_kernel, shm_perm);
 567
 568                inode = shp->shm_file->f_path.dentry->d_inode;
 569
 570                if (is_file_hugepages(shp->shm_file)) {
 571                        struct address_space *mapping = inode->i_mapping;
 572                        struct hstate *h = hstate_file(shp->shm_file);
 573                        *rss += pages_per_huge_page(h) * mapping->nrpages;
 574                } else {
 575#ifdef CONFIG_SHMEM
 576                        struct shmem_inode_info *info = SHMEM_I(inode);
 577                        spin_lock(&info->lock);
 578                        *rss += inode->i_mapping->nrpages;
 579                        *swp += info->swapped;
 580                        spin_unlock(&info->lock);
 581#else
 582                        *rss += inode->i_mapping->nrpages;
 583#endif
 584                }
 585
 586                total++;
 587        }
 588}
 589
 590/*
 591 * This function handles some shmctl commands which require the rw_mutex
 592 * to be held in write mode.
 593 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 594 */
 595static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 596                       struct shmid_ds __user *buf, int version)
 597{
 598        struct kern_ipc_perm *ipcp;
 599        struct shmid64_ds shmid64;
 600        struct shmid_kernel *shp;
 601        int err;
 602
 603        if (cmd == IPC_SET) {
 604                if (copy_shmid_from_user(&shmid64, buf, version))
 605                        return -EFAULT;
 606        }
 607
 608        ipcp = ipcctl_pre_down(&shm_ids(ns), shmid, cmd, &shmid64.shm_perm, 0);
 609        if (IS_ERR(ipcp))
 610                return PTR_ERR(ipcp);
 611
 612        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 613
 614        err = security_shm_shmctl(shp, cmd);
 615        if (err)
 616                goto out_unlock;
 617        switch (cmd) {
 618        case IPC_RMID:
 619                do_shm_rmid(ns, ipcp);
 620                goto out_up;
 621        case IPC_SET:
 622                ipc_update_perm(&shmid64.shm_perm, ipcp);
 623                shp->shm_ctim = get_seconds();
 624                break;
 625        default:
 626                err = -EINVAL;
 627        }
 628out_unlock:
 629        shm_unlock(shp);
 630out_up:
 631        up_write(&shm_ids(ns).rw_mutex);
 632        return err;
 633}
 634
 635SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 636{
 637        struct shmid_kernel *shp;
 638        int err, version;
 639        struct ipc_namespace *ns;
 640
 641        if (cmd < 0 || shmid < 0) {
 642                err = -EINVAL;
 643                goto out;
 644        }
 645
 646        version = ipc_parse_version(&cmd);
 647        ns = current->nsproxy->ipc_ns;
 648
 649        switch (cmd) { /* replace with proc interface ? */
 650        case IPC_INFO:
 651        {
 652                struct shminfo64 shminfo;
 653
 654                err = security_shm_shmctl(NULL, cmd);
 655                if (err)
 656                        return err;
 657
 658                memset(&shminfo, 0, sizeof(shminfo));
 659                shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 660                shminfo.shmmax = ns->shm_ctlmax;
 661                shminfo.shmall = ns->shm_ctlall;
 662
 663                shminfo.shmmin = SHMMIN;
 664                if(copy_shminfo_to_user (buf, &shminfo, version))
 665                        return -EFAULT;
 666
 667                down_read(&shm_ids(ns).rw_mutex);
 668                err = ipc_get_maxid(&shm_ids(ns));
 669                up_read(&shm_ids(ns).rw_mutex);
 670
 671                if(err<0)
 672                        err = 0;
 673                goto out;
 674        }
 675        case SHM_INFO:
 676        {
 677                struct shm_info shm_info;
 678
 679                err = security_shm_shmctl(NULL, cmd);
 680                if (err)
 681                        return err;
 682
 683                memset(&shm_info, 0, sizeof(shm_info));
 684                down_read(&shm_ids(ns).rw_mutex);
 685                shm_info.used_ids = shm_ids(ns).in_use;
 686                shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 687                shm_info.shm_tot = ns->shm_tot;
 688                shm_info.swap_attempts = 0;
 689                shm_info.swap_successes = 0;
 690                err = ipc_get_maxid(&shm_ids(ns));
 691                up_read(&shm_ids(ns).rw_mutex);
 692                if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 693                        err = -EFAULT;
 694                        goto out;
 695                }
 696
 697                err = err < 0 ? 0 : err;
 698                goto out;
 699        }
 700        case SHM_STAT:
 701        case IPC_STAT:
 702        {
 703                struct shmid64_ds tbuf;
 704                int result;
 705
 706                if (cmd == SHM_STAT) {
 707                        shp = shm_lock(ns, shmid);
 708                        if (IS_ERR(shp)) {
 709                                err = PTR_ERR(shp);
 710                                goto out;
 711                        }
 712                        result = shp->shm_perm.id;
 713                } else {
 714                        shp = shm_lock_check(ns, shmid);
 715                        if (IS_ERR(shp)) {
 716                                err = PTR_ERR(shp);
 717                                goto out;
 718                        }
 719                        result = 0;
 720                }
 721                err = -EACCES;
 722                if (ipcperms (&shp->shm_perm, S_IRUGO))
 723                        goto out_unlock;
 724                err = security_shm_shmctl(shp, cmd);
 725                if (err)
 726                        goto out_unlock;
 727                memset(&tbuf, 0, sizeof(tbuf));
 728                kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 729                tbuf.shm_segsz  = shp->shm_segsz;
 730                tbuf.shm_atime  = shp->shm_atim;
 731                tbuf.shm_dtime  = shp->shm_dtim;
 732                tbuf.shm_ctime  = shp->shm_ctim;
 733                tbuf.shm_cpid   = shp->shm_cprid;
 734                tbuf.shm_lpid   = shp->shm_lprid;
 735                tbuf.shm_nattch = shp->shm_nattch;
 736                shm_unlock(shp);
 737                if(copy_shmid_to_user (buf, &tbuf, version))
 738                        err = -EFAULT;
 739                else
 740                        err = result;
 741                goto out;
 742        }
 743        case SHM_LOCK:
 744        case SHM_UNLOCK:
 745        {
 746                struct file *uninitialized_var(shm_file);
 747
 748                lru_add_drain_all();  /* drain pagevecs to lru lists */
 749
 750                shp = shm_lock_check(ns, shmid);
 751                if (IS_ERR(shp)) {
 752                        err = PTR_ERR(shp);
 753                        goto out;
 754                }
 755
 756                audit_ipc_obj(&(shp->shm_perm));
 757
 758                if (!capable(CAP_IPC_LOCK)) {
 759                        uid_t euid = current_euid();
 760                        err = -EPERM;
 761                        if (euid != shp->shm_perm.uid &&
 762                            euid != shp->shm_perm.cuid)
 763                                goto out_unlock;
 764                        if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
 765                                goto out_unlock;
 766                }
 767
 768                err = security_shm_shmctl(shp, cmd);
 769                if (err)
 770                        goto out_unlock;
 771                
 772                if(cmd==SHM_LOCK) {
 773                        struct user_struct *user = current_user();
 774                        if (!is_file_hugepages(shp->shm_file)) {
 775                                err = shmem_lock(shp->shm_file, 1, user);
 776                                if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
 777                                        shp->shm_perm.mode |= SHM_LOCKED;
 778                                        shp->mlock_user = user;
 779                                }
 780                        }
 781                } else if (!is_file_hugepages(shp->shm_file)) {
 782                        shmem_lock(shp->shm_file, 0, shp->mlock_user);
 783                        shp->shm_perm.mode &= ~SHM_LOCKED;
 784                        shp->mlock_user = NULL;
 785                }
 786                shm_unlock(shp);
 787                goto out;
 788        }
 789        case IPC_RMID:
 790        case IPC_SET:
 791                err = shmctl_down(ns, shmid, cmd, buf, version);
 792                return err;
 793        default:
 794                return -EINVAL;
 795        }
 796
 797out_unlock:
 798        shm_unlock(shp);
 799out:
 800        return err;
 801}
 802
 803/*
 804 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 805 *
 806 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 807 * "raddr" thing points to kernel space, and there has to be a wrapper around
 808 * this.
 809 */
 810long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 811{
 812        struct shmid_kernel *shp;
 813        unsigned long addr;
 814        unsigned long size;
 815        struct file * file;
 816        int    err;
 817        unsigned long flags;
 818        unsigned long prot;
 819        int acc_mode;
 820        unsigned long user_addr;
 821        struct ipc_namespace *ns;
 822        struct shm_file_data *sfd;
 823        struct path path;
 824        fmode_t f_mode;
 825
 826        err = -EINVAL;
 827        if (shmid < 0)
 828                goto out;
 829        else if ((addr = (ulong)shmaddr)) {
 830                if (addr & (SHMLBA-1)) {
 831                        if (shmflg & SHM_RND)
 832                                addr &= ~(SHMLBA-1);       /* round down */
 833                        else
 834#ifndef __ARCH_FORCE_SHMLBA
 835                                if (addr & ~PAGE_MASK)
 836#endif
 837                                        goto out;
 838                }
 839                flags = MAP_SHARED | MAP_FIXED;
 840        } else {
 841                if ((shmflg & SHM_REMAP))
 842                        goto out;
 843
 844                flags = MAP_SHARED;
 845        }
 846
 847        if (shmflg & SHM_RDONLY) {
 848                prot = PROT_READ;
 849                acc_mode = S_IRUGO;
 850                f_mode = FMODE_READ;
 851        } else {
 852                prot = PROT_READ | PROT_WRITE;
 853                acc_mode = S_IRUGO | S_IWUGO;
 854                f_mode = FMODE_READ | FMODE_WRITE;
 855        }
 856        if (shmflg & SHM_EXEC) {
 857                prot |= PROT_EXEC;
 858                acc_mode |= S_IXUGO;
 859        }
 860
 861        /*
 862         * We cannot rely on the fs check since SYSV IPC does have an
 863         * additional creator id...
 864         */
 865        ns = current->nsproxy->ipc_ns;
 866        shp = shm_lock_check(ns, shmid);
 867        if (IS_ERR(shp)) {
 868                err = PTR_ERR(shp);
 869                goto out;
 870        }
 871
 872        err = -EACCES;
 873        if (ipcperms(&shp->shm_perm, acc_mode))
 874                goto out_unlock;
 875
 876        err = security_shm_shmat(shp, shmaddr, shmflg);
 877        if (err)
 878                goto out_unlock;
 879
 880        path = shp->shm_file->f_path;
 881        path_get(&path);
 882        shp->shm_nattch++;
 883        size = i_size_read(path.dentry->d_inode);
 884        shm_unlock(shp);
 885
 886        err = -ENOMEM;
 887        sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
 888        if (!sfd)
 889                goto out_put_dentry;
 890
 891        file = alloc_file(&path, f_mode,
 892                          is_file_hugepages(shp->shm_file) ?
 893                                &shm_file_operations_huge :
 894                                &shm_file_operations);
 895        if (!file)
 896                goto out_free;
 897
 898        file->private_data = sfd;
 899        file->f_mapping = shp->shm_file->f_mapping;
 900        sfd->id = shp->shm_perm.id;
 901        sfd->ns = get_ipc_ns(ns);
 902        sfd->file = shp->shm_file;
 903        sfd->vm_ops = NULL;
 904
 905        down_write(&current->mm->mmap_sem);
 906        if (addr && !(shmflg & SHM_REMAP)) {
 907                err = -EINVAL;
 908                if (find_vma_intersection(current->mm, addr, addr + size))
 909                        goto invalid;
 910                /*
 911                 * If shm segment goes below stack, make sure there is some
 912                 * space left for the stack to grow (at least 4 pages).
 913                 */
 914                if (addr < current->mm->start_stack &&
 915                    addr > current->mm->start_stack - size - PAGE_SIZE * 5)
 916                        goto invalid;
 917        }
 918                
 919        user_addr = do_mmap (file, addr, size, prot, flags, 0);
 920        *raddr = user_addr;
 921        err = 0;
 922        if (IS_ERR_VALUE(user_addr))
 923                err = (long)user_addr;
 924invalid:
 925        up_write(&current->mm->mmap_sem);
 926
 927        fput(file);
 928
 929out_nattch:
 930        down_write(&shm_ids(ns).rw_mutex);
 931        shp = shm_lock(ns, shmid);
 932        BUG_ON(IS_ERR(shp));
 933        shp->shm_nattch--;
 934        if(shp->shm_nattch == 0 &&
 935           shp->shm_perm.mode & SHM_DEST)
 936                shm_destroy(ns, shp);
 937        else
 938                shm_unlock(shp);
 939        up_write(&shm_ids(ns).rw_mutex);
 940
 941out:
 942        return err;
 943
 944out_unlock:
 945        shm_unlock(shp);
 946        goto out;
 947
 948out_free:
 949        kfree(sfd);
 950out_put_dentry:
 951        path_put(&path);
 952        goto out_nattch;
 953}
 954
 955SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
 956{
 957        unsigned long ret;
 958        long err;
 959
 960        err = do_shmat(shmid, shmaddr, shmflg, &ret);
 961        if (err)
 962                return err;
 963        force_successful_syscall_return();
 964        return (long)ret;
 965}
 966
 967/*
 968 * detach and kill segment if marked destroyed.
 969 * The work is done in shm_close.
 970 */
 971SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
 972{
 973        struct mm_struct *mm = current->mm;
 974        struct vm_area_struct *vma;
 975        unsigned long addr = (unsigned long)shmaddr;
 976        int retval = -EINVAL;
 977#ifdef CONFIG_MMU
 978        loff_t size = 0;
 979        struct vm_area_struct *next;
 980#endif
 981
 982        if (addr & ~PAGE_MASK)
 983                return retval;
 984
 985        down_write(&mm->mmap_sem);
 986
 987        /*
 988         * This function tries to be smart and unmap shm segments that
 989         * were modified by partial mlock or munmap calls:
 990         * - It first determines the size of the shm segment that should be
 991         *   unmapped: It searches for a vma that is backed by shm and that
 992         *   started at address shmaddr. It records it's size and then unmaps
 993         *   it.
 994         * - Then it unmaps all shm vmas that started at shmaddr and that
 995         *   are within the initially determined size.
 996         * Errors from do_munmap are ignored: the function only fails if
 997         * it's called with invalid parameters or if it's called to unmap
 998         * a part of a vma. Both calls in this function are for full vmas,
 999         * the parameters are directly copied from the vma itself and always
1000         * valid - therefore do_munmap cannot fail. (famous last words?)
1001         */
1002        /*
1003         * If it had been mremap()'d, the starting address would not
1004         * match the usual checks anyway. So assume all vma's are
1005         * above the starting address given.
1006         */
1007        vma = find_vma(mm, addr);
1008
1009#ifdef CONFIG_MMU
1010        while (vma) {
1011                next = vma->vm_next;
1012
1013                /*
1014                 * Check if the starting address would match, i.e. it's
1015                 * a fragment created by mprotect() and/or munmap(), or it
1016                 * otherwise it starts at this address with no hassles.
1017                 */
1018                if ((vma->vm_ops == &shm_vm_ops) &&
1019                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1020
1021
1022                        size = vma->vm_file->f_path.dentry->d_inode->i_size;
1023                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1024                        /*
1025                         * We discovered the size of the shm segment, so
1026                         * break out of here and fall through to the next
1027                         * loop that uses the size information to stop
1028                         * searching for matching vma's.
1029                         */
1030                        retval = 0;
1031                        vma = next;
1032                        break;
1033                }
1034                vma = next;
1035        }
1036
1037        /*
1038         * We need look no further than the maximum address a fragment
1039         * could possibly have landed at. Also cast things to loff_t to
1040         * prevent overflows and make comparisions vs. equal-width types.
1041         */
1042        size = PAGE_ALIGN(size);
1043        while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1044                next = vma->vm_next;
1045
1046                /* finding a matching vma now does not alter retval */
1047                if ((vma->vm_ops == &shm_vm_ops) &&
1048                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1049
1050                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1051                vma = next;
1052        }
1053
1054#else /* CONFIG_MMU */
1055        /* under NOMMU conditions, the exact address to be destroyed must be
1056         * given */
1057        retval = -EINVAL;
1058        if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1059                do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1060                retval = 0;
1061        }
1062
1063#endif
1064
1065        up_write(&mm->mmap_sem);
1066        return retval;
1067}
1068
1069#ifdef CONFIG_PROC_FS
1070static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1071{
1072        struct shmid_kernel *shp = it;
1073
1074#if BITS_PER_LONG <= 32
1075#define SIZE_SPEC "%10lu"
1076#else
1077#define SIZE_SPEC "%21lu"
1078#endif
1079
1080        return seq_printf(s,
1081                          "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1082                          "%5lu %5u %5u %5u %5u %10lu %10lu %10lu\n",
1083                          shp->shm_perm.key,
1084                          shp->shm_perm.id,
1085                          shp->shm_perm.mode,
1086                          shp->shm_segsz,
1087                          shp->shm_cprid,
1088                          shp->shm_lprid,
1089                          shp->shm_nattch,
1090                          shp->shm_perm.uid,
1091                          shp->shm_perm.gid,
1092                          shp->shm_perm.cuid,
1093                          shp->shm_perm.cgid,
1094                          shp->shm_atim,
1095                          shp->shm_dtim,
1096                          shp->shm_ctim);
1097}
1098#endif
1099