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
  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_rmid_forced = 0;
  78        ns->shm_tot = 0;
  79        ipc_init_ids(&shm_ids(ns));
  80}
  81
  82/*
  83 * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
  84 * Only shm_ids.rw_mutex remains locked on exit.
  85 */
  86static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
  87{
  88        struct shmid_kernel *shp;
  89        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
  90
  91        if (shp->shm_nattch){
  92                shp->shm_perm.mode |= SHM_DEST;
  93                /* Do not find it any more */
  94                shp->shm_perm.key = IPC_PRIVATE;
  95                shm_unlock(shp);
  96        } else
  97                shm_destroy(ns, shp);
  98}
  99
 100#ifdef CONFIG_IPC_NS
 101void shm_exit_ns(struct ipc_namespace *ns)
 102{
 103        free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 104        idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
 105}
 106#endif
 107
 108static int __init ipc_ns_init(void)
 109{
 110        shm_init_ns(&init_ipc_ns);
 111        return 0;
 112}
 113
 114pure_initcall(ipc_ns_init);
 115
 116void __init shm_init (void)
 117{
 118        ipc_init_proc_interface("sysvipc/shm",
 119#if BITS_PER_LONG <= 32
 120                                "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
 121#else
 122                                "       key      shmid perms                  size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime                   rss                  swap\n",
 123#endif
 124                                IPC_SHM_IDS, sysvipc_shm_proc_show);
 125}
 126
 127/*
 128 * shm_lock_(check_) routines are called in the paths where the rw_mutex
 129 * is not necessarily held.
 130 */
 131static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 132{
 133        struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 134
 135        if (IS_ERR(ipcp))
 136                return (struct shmid_kernel *)ipcp;
 137
 138        return container_of(ipcp, struct shmid_kernel, shm_perm);
 139}
 140
 141static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
 142{
 143        rcu_read_lock();
 144        spin_lock(&ipcp->shm_perm.lock);
 145}
 146
 147static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
 148                                                int id)
 149{
 150        struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
 151
 152        if (IS_ERR(ipcp))
 153                return (struct shmid_kernel *)ipcp;
 154
 155        return container_of(ipcp, struct shmid_kernel, shm_perm);
 156}
 157
 158static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 159{
 160        ipc_rmid(&shm_ids(ns), &s->shm_perm);
 161}
 162
 163
 164/* This is called by fork, once for every shm attach. */
 165static void shm_open(struct vm_area_struct *vma)
 166{
 167        struct file *file = vma->vm_file;
 168        struct shm_file_data *sfd = shm_file_data(file);
 169        struct shmid_kernel *shp;
 170
 171        shp = shm_lock(sfd->ns, sfd->id);
 172        BUG_ON(IS_ERR(shp));
 173        shp->shm_atim = get_seconds();
 174        shp->shm_lprid = task_tgid_vnr(current);
 175        shp->shm_nattch++;
 176        shm_unlock(shp);
 177}
 178
 179/*
 180 * shm_destroy - free the struct shmid_kernel
 181 *
 182 * @ns: namespace
 183 * @shp: struct to free
 184 *
 185 * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
 186 * but returns with shp unlocked and freed.
 187 */
 188static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 189{
 190        ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
 191        shm_rmid(ns, shp);
 192        shm_unlock(shp);
 193        if (!is_file_hugepages(shp->shm_file))
 194                shmem_lock(shp->shm_file, 0, shp->mlock_user);
 195        else if (shp->mlock_user)
 196                user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
 197                                                shp->mlock_user);
 198        fput (shp->shm_file);
 199        security_shm_free(shp);
 200        ipc_rcu_putref(shp);
 201}
 202
 203/*
 204 * shm_may_destroy - identifies whether shm segment should be destroyed now
 205 *
 206 * Returns true if and only if there are no active users of the segment and
 207 * one of the following is true:
 208 *
 209 * 1) shmctl(id, IPC_RMID, NULL) was called for this shp
 210 *
 211 * 2) sysctl kernel.shm_rmid_forced is set to 1.
 212 */
 213static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 214{
 215        return (shp->shm_nattch == 0) &&
 216               (ns->shm_rmid_forced ||
 217                (shp->shm_perm.mode & SHM_DEST));
 218}
 219
 220/*
 221 * remove the attach descriptor vma.
 222 * free memory for segment if it is marked destroyed.
 223 * The descriptor has already been removed from the current->mm->mmap list
 224 * and will later be kfree()d.
 225 */
 226static void shm_close(struct vm_area_struct *vma)
 227{
 228        struct file * file = vma->vm_file;
 229        struct shm_file_data *sfd = shm_file_data(file);
 230        struct shmid_kernel *shp;
 231        struct ipc_namespace *ns = sfd->ns;
 232
 233        down_write(&shm_ids(ns).rw_mutex);
 234        /* remove from the list of attaches of the shm segment */
 235        shp = shm_lock(ns, sfd->id);
 236        BUG_ON(IS_ERR(shp));
 237        shp->shm_lprid = task_tgid_vnr(current);
 238        shp->shm_dtim = get_seconds();
 239        shp->shm_nattch--;
 240        if (shm_may_destroy(ns, shp))
 241                shm_destroy(ns, shp);
 242        else
 243                shm_unlock(shp);
 244        up_write(&shm_ids(ns).rw_mutex);
 245}
 246
 247/* Called with ns->shm_ids(ns).rw_mutex locked */
 248static int shm_try_destroy_current(int id, void *p, void *data)
 249{
 250        struct ipc_namespace *ns = data;
 251        struct kern_ipc_perm *ipcp = p;
 252        struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 253
 254        if (shp->shm_creator != current)
 255                return 0;
 256
 257        /*
 258         * Mark it as orphaned to destroy the segment when
 259         * kernel.shm_rmid_forced is changed.
 260         * It is noop if the following shm_may_destroy() returns true.
 261         */
 262        shp->shm_creator = NULL;
 263
 264        /*
 265         * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
 266         * is not set, it shouldn't be deleted here.
 267         */
 268        if (!ns->shm_rmid_forced)
 269                return 0;
 270
 271        if (shm_may_destroy(ns, shp)) {
 272                shm_lock_by_ptr(shp);
 273                shm_destroy(ns, shp);
 274        }
 275        return 0;
 276}
 277
 278/* Called with ns->shm_ids(ns).rw_mutex locked */
 279static int shm_try_destroy_orphaned(int id, void *p, void *data)
 280{
 281        struct ipc_namespace *ns = data;
 282        struct kern_ipc_perm *ipcp = p;
 283        struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 284
 285        /*
 286         * We want to destroy segments without users and with already
 287         * exit'ed originating process.
 288         *
 289         * As shp->* are changed under rw_mutex, it's safe to skip shp locking.
 290         */
 291        if (shp->shm_creator != NULL)
 292                return 0;
 293
 294        if (shm_may_destroy(ns, shp)) {
 295                shm_lock_by_ptr(shp);
 296                shm_destroy(ns, shp);
 297        }
 298        return 0;
 299}
 300
 301void shm_destroy_orphaned(struct ipc_namespace *ns)
 302{
 303        down_write(&shm_ids(ns).rw_mutex);
 304        if (shm_ids(ns).in_use)
 305                idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
 306        up_write(&shm_ids(ns).rw_mutex);
 307}
 308
 309
 310void exit_shm(struct task_struct *task)
 311{
 312        struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 313
 314        if (shm_ids(ns).in_use == 0)
 315                return;
 316
 317        /* Destroy all already created segments, but not mapped yet */
 318        down_write(&shm_ids(ns).rw_mutex);
 319        if (shm_ids(ns).in_use)
 320                idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
 321        up_write(&shm_ids(ns).rw_mutex);
 322}
 323
 324static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 325{
 326        struct file *file = vma->vm_file;
 327        struct shm_file_data *sfd = shm_file_data(file);
 328
 329        return sfd->vm_ops->fault(vma, vmf);
 330}
 331
 332#ifdef CONFIG_NUMA
 333static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 334{
 335        struct file *file = vma->vm_file;
 336        struct shm_file_data *sfd = shm_file_data(file);
 337        int err = 0;
 338        if (sfd->vm_ops->set_policy)
 339                err = sfd->vm_ops->set_policy(vma, new);
 340        return err;
 341}
 342
 343static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
 344                                        unsigned long addr)
 345{
 346        struct file *file = vma->vm_file;
 347        struct shm_file_data *sfd = shm_file_data(file);
 348        struct mempolicy *pol = NULL;
 349
 350        if (sfd->vm_ops->get_policy)
 351                pol = sfd->vm_ops->get_policy(vma, addr);
 352        else if (vma->vm_policy)
 353                pol = vma->vm_policy;
 354
 355        return pol;
 356}
 357#endif
 358
 359static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 360{
 361        struct shm_file_data *sfd = shm_file_data(file);
 362        int ret;
 363
 364        ret = sfd->file->f_op->mmap(sfd->file, vma);
 365        if (ret != 0)
 366                return ret;
 367        sfd->vm_ops = vma->vm_ops;
 368#ifdef CONFIG_MMU
 369        BUG_ON(!sfd->vm_ops->fault);
 370#endif
 371        vma->vm_ops = &shm_vm_ops;
 372        shm_open(vma);
 373
 374        return ret;
 375}
 376
 377static int shm_release(struct inode *ino, struct file *file)
 378{
 379        struct shm_file_data *sfd = shm_file_data(file);
 380
 381        put_ipc_ns(sfd->ns);
 382        shm_file_data(file) = NULL;
 383        kfree(sfd);
 384        return 0;
 385}
 386
 387static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 388{
 389        struct shm_file_data *sfd = shm_file_data(file);
 390
 391        if (!sfd->file->f_op->fsync)
 392                return -EINVAL;
 393        return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
 394}
 395
 396static unsigned long shm_get_unmapped_area(struct file *file,
 397        unsigned long addr, unsigned long len, unsigned long pgoff,
 398        unsigned long flags)
 399{
 400        struct shm_file_data *sfd = shm_file_data(file);
 401        return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
 402                                                pgoff, flags);
 403}
 404
 405static const struct file_operations shm_file_operations = {
 406        .mmap           = shm_mmap,
 407        .fsync          = shm_fsync,
 408        .release        = shm_release,
 409#ifndef CONFIG_MMU
 410        .get_unmapped_area      = shm_get_unmapped_area,
 411#endif
 412        .llseek         = noop_llseek,
 413};
 414
 415static const struct file_operations shm_file_operations_huge = {
 416        .mmap           = shm_mmap,
 417        .fsync          = shm_fsync,
 418        .release        = shm_release,
 419        .get_unmapped_area      = shm_get_unmapped_area,
 420        .llseek         = noop_llseek,
 421};
 422
 423int is_file_shm_hugepages(struct file *file)
 424{
 425        return file->f_op == &shm_file_operations_huge;
 426}
 427
 428static const struct vm_operations_struct shm_vm_ops = {
 429        .open   = shm_open,     /* callback for a new vm-area open */
 430        .close  = shm_close,    /* callback for when the vm-area is released */
 431        .fault  = shm_fault,
 432#if defined(CONFIG_NUMA)
 433        .set_policy = shm_set_policy,
 434        .get_policy = shm_get_policy,
 435#endif
 436};
 437
 438/**
 439 * newseg - Create a new shared memory segment
 440 * @ns: namespace
 441 * @params: ptr to the structure that contains key, size and shmflg
 442 *
 443 * Called with shm_ids.rw_mutex held as a writer.
 444 */
 445
 446static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 447{
 448        key_t key = params->key;
 449        int shmflg = params->flg;
 450        size_t size = params->u.size;
 451        int error;
 452        struct shmid_kernel *shp;
 453        int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
 454        struct file * file;
 455        char name[13];
 456        int id;
 457        vm_flags_t acctflag = 0;
 458
 459        if (size < SHMMIN || size > ns->shm_ctlmax)
 460                return -EINVAL;
 461
 462        if (ns->shm_tot + numpages > ns->shm_ctlall)
 463                return -ENOSPC;
 464
 465        shp = ipc_rcu_alloc(sizeof(*shp));
 466        if (!shp)
 467                return -ENOMEM;
 468
 469        shp->shm_perm.key = key;
 470        shp->shm_perm.mode = (shmflg & S_IRWXUGO);
 471        shp->mlock_user = NULL;
 472
 473        shp->shm_perm.security = NULL;
 474        error = security_shm_alloc(shp);
 475        if (error) {
 476                ipc_rcu_putref(shp);
 477                return error;
 478        }
 479
 480        sprintf (name, "SYSV%08x", key);
 481        if (shmflg & SHM_HUGETLB) {
 482                /* hugetlb_file_setup applies strict accounting */
 483                if (shmflg & SHM_NORESERVE)
 484                        acctflag = VM_NORESERVE;
 485                file = hugetlb_file_setup(name, size, acctflag,
 486                                        &shp->mlock_user, HUGETLB_SHMFS_INODE);
 487        } else {
 488                /*
 489                 * Do not allow no accounting for OVERCOMMIT_NEVER, even
 490                 * if it's asked for.
 491                 */
 492                if  ((shmflg & SHM_NORESERVE) &&
 493                                sysctl_overcommit_memory != OVERCOMMIT_NEVER)
 494                        acctflag = VM_NORESERVE;
 495                file = shmem_file_setup(name, size, acctflag);
 496        }
 497        error = PTR_ERR(file);
 498        if (IS_ERR(file))
 499                goto no_file;
 500
 501        id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
 502        if (id < 0) {
 503                error = id;
 504                goto no_id;
 505        }
 506
 507        shp->shm_cprid = task_tgid_vnr(current);
 508        shp->shm_lprid = 0;
 509        shp->shm_atim = shp->shm_dtim = 0;
 510        shp->shm_ctim = get_seconds();
 511        shp->shm_segsz = size;
 512        shp->shm_nattch = 0;
 513        shp->shm_file = file;
 514        shp->shm_creator = current;
 515        /*
 516         * shmid gets reported as "inode#" in /proc/pid/maps.
 517         * proc-ps tools use this. Changing this will break them.
 518         */
 519        file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 520
 521        ns->shm_tot += numpages;
 522        error = shp->shm_perm.id;
 523        shm_unlock(shp);
 524        return error;
 525
 526no_id:
 527        if (is_file_hugepages(file) && shp->mlock_user)
 528                user_shm_unlock(size, shp->mlock_user);
 529        fput(file);
 530no_file:
 531        security_shm_free(shp);
 532        ipc_rcu_putref(shp);
 533        return error;
 534}
 535
 536/*
 537 * Called with shm_ids.rw_mutex and ipcp locked.
 538 */
 539static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 540{
 541        struct shmid_kernel *shp;
 542
 543        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 544        return security_shm_associate(shp, shmflg);
 545}
 546
 547/*
 548 * Called with shm_ids.rw_mutex and ipcp locked.
 549 */
 550static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
 551                                struct ipc_params *params)
 552{
 553        struct shmid_kernel *shp;
 554
 555        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 556        if (shp->shm_segsz < params->u.size)
 557                return -EINVAL;
 558
 559        return 0;
 560}
 561
 562SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
 563{
 564        struct ipc_namespace *ns;
 565        struct ipc_ops shm_ops;
 566        struct ipc_params shm_params;
 567
 568        ns = current->nsproxy->ipc_ns;
 569
 570        shm_ops.getnew = newseg;
 571        shm_ops.associate = shm_security;
 572        shm_ops.more_checks = shm_more_checks;
 573
 574        shm_params.key = key;
 575        shm_params.flg = shmflg;
 576        shm_params.u.size = size;
 577
 578        return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 579}
 580
 581static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 582{
 583        switch(version) {
 584        case IPC_64:
 585                return copy_to_user(buf, in, sizeof(*in));
 586        case IPC_OLD:
 587            {
 588                struct shmid_ds out;
 589
 590                memset(&out, 0, sizeof(out));
 591                ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
 592                out.shm_segsz   = in->shm_segsz;
 593                out.shm_atime   = in->shm_atime;
 594                out.shm_dtime   = in->shm_dtime;
 595                out.shm_ctime   = in->shm_ctime;
 596                out.shm_cpid    = in->shm_cpid;
 597                out.shm_lpid    = in->shm_lpid;
 598                out.shm_nattch  = in->shm_nattch;
 599
 600                return copy_to_user(buf, &out, sizeof(out));
 601            }
 602        default:
 603                return -EINVAL;
 604        }
 605}
 606
 607static inline unsigned long
 608copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 609{
 610        switch(version) {
 611        case IPC_64:
 612                if (copy_from_user(out, buf, sizeof(*out)))
 613                        return -EFAULT;
 614                return 0;
 615        case IPC_OLD:
 616            {
 617                struct shmid_ds tbuf_old;
 618
 619                if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
 620                        return -EFAULT;
 621
 622                out->shm_perm.uid       = tbuf_old.shm_perm.uid;
 623                out->shm_perm.gid       = tbuf_old.shm_perm.gid;
 624                out->shm_perm.mode      = tbuf_old.shm_perm.mode;
 625
 626                return 0;
 627            }
 628        default:
 629                return -EINVAL;
 630        }
 631}
 632
 633static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 634{
 635        switch(version) {
 636        case IPC_64:
 637                return copy_to_user(buf, in, sizeof(*in));
 638        case IPC_OLD:
 639            {
 640                struct shminfo out;
 641
 642                if(in->shmmax > INT_MAX)
 643                        out.shmmax = INT_MAX;
 644                else
 645                        out.shmmax = (int)in->shmmax;
 646
 647                out.shmmin      = in->shmmin;
 648                out.shmmni      = in->shmmni;
 649                out.shmseg      = in->shmseg;
 650                out.shmall      = in->shmall; 
 651
 652                return copy_to_user(buf, &out, sizeof(out));
 653            }
 654        default:
 655                return -EINVAL;
 656        }
 657}
 658
 659/*
 660 * Calculate and add used RSS and swap pages of a shm.
 661 * Called with shm_ids.rw_mutex held as a reader
 662 */
 663static void shm_add_rss_swap(struct shmid_kernel *shp,
 664        unsigned long *rss_add, unsigned long *swp_add)
 665{
 666        struct inode *inode;
 667
 668        inode = shp->shm_file->f_path.dentry->d_inode;
 669
 670        if (is_file_hugepages(shp->shm_file)) {
 671                struct address_space *mapping = inode->i_mapping;
 672                struct hstate *h = hstate_file(shp->shm_file);
 673                *rss_add += pages_per_huge_page(h) * mapping->nrpages;
 674        } else {
 675#ifdef CONFIG_SHMEM
 676                struct shmem_inode_info *info = SHMEM_I(inode);
 677                spin_lock(&info->lock);
 678                *rss_add += inode->i_mapping->nrpages;
 679                *swp_add += info->swapped;
 680                spin_unlock(&info->lock);
 681#else
 682                *rss_add += inode->i_mapping->nrpages;
 683#endif
 684        }
 685}
 686
 687/*
 688 * Called with shm_ids.rw_mutex held as a reader
 689 */
 690static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
 691                unsigned long *swp)
 692{
 693        int next_id;
 694        int total, in_use;
 695
 696        *rss = 0;
 697        *swp = 0;
 698
 699        in_use = shm_ids(ns).in_use;
 700
 701        for (total = 0, next_id = 0; total < in_use; next_id++) {
 702                struct kern_ipc_perm *ipc;
 703                struct shmid_kernel *shp;
 704
 705                ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
 706                if (ipc == NULL)
 707                        continue;
 708                shp = container_of(ipc, struct shmid_kernel, shm_perm);
 709
 710                shm_add_rss_swap(shp, rss, swp);
 711
 712                total++;
 713        }
 714}
 715
 716/*
 717 * This function handles some shmctl commands which require the rw_mutex
 718 * to be held in write mode.
 719 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 720 */
 721static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
 722                       struct shmid_ds __user *buf, int version)
 723{
 724        struct kern_ipc_perm *ipcp;
 725        struct shmid64_ds shmid64;
 726        struct shmid_kernel *shp;
 727        int err;
 728
 729        if (cmd == IPC_SET) {
 730                if (copy_shmid_from_user(&shmid64, buf, version))
 731                        return -EFAULT;
 732        }
 733
 734        ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
 735                               &shmid64.shm_perm, 0);
 736        if (IS_ERR(ipcp))
 737                return PTR_ERR(ipcp);
 738
 739        shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 740
 741        err = security_shm_shmctl(shp, cmd);
 742        if (err)
 743                goto out_unlock;
 744        switch (cmd) {
 745        case IPC_RMID:
 746                do_shm_rmid(ns, ipcp);
 747                goto out_up;
 748        case IPC_SET:
 749                ipc_update_perm(&shmid64.shm_perm, ipcp);
 750                shp->shm_ctim = get_seconds();
 751                break;
 752        default:
 753                err = -EINVAL;
 754        }
 755out_unlock:
 756        shm_unlock(shp);
 757out_up:
 758        up_write(&shm_ids(ns).rw_mutex);
 759        return err;
 760}
 761
 762SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
 763{
 764        struct shmid_kernel *shp;
 765        int err, version;
 766        struct ipc_namespace *ns;
 767
 768        if (cmd < 0 || shmid < 0) {
 769                err = -EINVAL;
 770                goto out;
 771        }
 772
 773        version = ipc_parse_version(&cmd);
 774        ns = current->nsproxy->ipc_ns;
 775
 776        switch (cmd) { /* replace with proc interface ? */
 777        case IPC_INFO:
 778        {
 779                struct shminfo64 shminfo;
 780
 781                err = security_shm_shmctl(NULL, cmd);
 782                if (err)
 783                        return err;
 784
 785                memset(&shminfo, 0, sizeof(shminfo));
 786                shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
 787                shminfo.shmmax = ns->shm_ctlmax;
 788                shminfo.shmall = ns->shm_ctlall;
 789
 790                shminfo.shmmin = SHMMIN;
 791                if(copy_shminfo_to_user (buf, &shminfo, version))
 792                        return -EFAULT;
 793
 794                down_read(&shm_ids(ns).rw_mutex);
 795                err = ipc_get_maxid(&shm_ids(ns));
 796                up_read(&shm_ids(ns).rw_mutex);
 797
 798                if(err<0)
 799                        err = 0;
 800                goto out;
 801        }
 802        case SHM_INFO:
 803        {
 804                struct shm_info shm_info;
 805
 806                err = security_shm_shmctl(NULL, cmd);
 807                if (err)
 808                        return err;
 809
 810                memset(&shm_info, 0, sizeof(shm_info));
 811                down_read(&shm_ids(ns).rw_mutex);
 812                shm_info.used_ids = shm_ids(ns).in_use;
 813                shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
 814                shm_info.shm_tot = ns->shm_tot;
 815                shm_info.swap_attempts = 0;
 816                shm_info.swap_successes = 0;
 817                err = ipc_get_maxid(&shm_ids(ns));
 818                up_read(&shm_ids(ns).rw_mutex);
 819                if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
 820                        err = -EFAULT;
 821                        goto out;
 822                }
 823
 824                err = err < 0 ? 0 : err;
 825                goto out;
 826        }
 827        case SHM_STAT:
 828        case IPC_STAT:
 829        {
 830                struct shmid64_ds tbuf;
 831                int result;
 832
 833                if (cmd == SHM_STAT) {
 834                        shp = shm_lock(ns, shmid);
 835                        if (IS_ERR(shp)) {
 836                                err = PTR_ERR(shp);
 837                                goto out;
 838                        }
 839                        result = shp->shm_perm.id;
 840                } else {
 841                        shp = shm_lock_check(ns, shmid);
 842                        if (IS_ERR(shp)) {
 843                                err = PTR_ERR(shp);
 844                                goto out;
 845                        }
 846                        result = 0;
 847                }
 848                err = -EACCES;
 849                if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
 850                        goto out_unlock;
 851                err = security_shm_shmctl(shp, cmd);
 852                if (err)
 853                        goto out_unlock;
 854                memset(&tbuf, 0, sizeof(tbuf));
 855                kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
 856                tbuf.shm_segsz  = shp->shm_segsz;
 857                tbuf.shm_atime  = shp->shm_atim;
 858                tbuf.shm_dtime  = shp->shm_dtim;
 859                tbuf.shm_ctime  = shp->shm_ctim;
 860                tbuf.shm_cpid   = shp->shm_cprid;
 861                tbuf.shm_lpid   = shp->shm_lprid;
 862                tbuf.shm_nattch = shp->shm_nattch;
 863                shm_unlock(shp);
 864                if(copy_shmid_to_user (buf, &tbuf, version))
 865                        err = -EFAULT;
 866                else
 867                        err = result;
 868                goto out;
 869        }
 870        case SHM_LOCK:
 871        case SHM_UNLOCK:
 872        {
 873                struct file *uninitialized_var(shm_file);
 874
 875                lru_add_drain_all();  /* drain pagevecs to lru lists */
 876
 877                shp = shm_lock_check(ns, shmid);
 878                if (IS_ERR(shp)) {
 879                        err = PTR_ERR(shp);
 880                        goto out;
 881                }
 882
 883                audit_ipc_obj(&(shp->shm_perm));
 884
 885                if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
 886                        uid_t euid = current_euid();
 887                        err = -EPERM;
 888                        if (euid != shp->shm_perm.uid &&
 889                            euid != shp->shm_perm.cuid)
 890                                goto out_unlock;
 891                        if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
 892                                goto out_unlock;
 893                }
 894
 895                err = security_shm_shmctl(shp, cmd);
 896                if (err)
 897                        goto out_unlock;
 898                
 899                if(cmd==SHM_LOCK) {
 900                        struct user_struct *user = current_user();
 901                        if (!is_file_hugepages(shp->shm_file)) {
 902                                err = shmem_lock(shp->shm_file, 1, user);
 903                                if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
 904                                        shp->shm_perm.mode |= SHM_LOCKED;
 905                                        shp->mlock_user = user;
 906                                }
 907                        }
 908                } else if (!is_file_hugepages(shp->shm_file)) {
 909                        shmem_lock(shp->shm_file, 0, shp->mlock_user);
 910                        shp->shm_perm.mode &= ~SHM_LOCKED;
 911                        shp->mlock_user = NULL;
 912                }
 913                shm_unlock(shp);
 914                goto out;
 915        }
 916        case IPC_RMID:
 917        case IPC_SET:
 918                err = shmctl_down(ns, shmid, cmd, buf, version);
 919                return err;
 920        default:
 921                return -EINVAL;
 922        }
 923
 924out_unlock:
 925        shm_unlock(shp);
 926out:
 927        return err;
 928}
 929
 930/*
 931 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 932 *
 933 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 934 * "raddr" thing points to kernel space, and there has to be a wrapper around
 935 * this.
 936 */
 937long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 938{
 939        struct shmid_kernel *shp;
 940        unsigned long addr;
 941        unsigned long size;
 942        struct file * file;
 943        int    err;
 944        unsigned long flags;
 945        unsigned long prot;
 946        int acc_mode;
 947        unsigned long user_addr;
 948        struct ipc_namespace *ns;
 949        struct shm_file_data *sfd;
 950        struct path path;
 951        fmode_t f_mode;
 952
 953        err = -EINVAL;
 954        if (shmid < 0)
 955                goto out;
 956        else if ((addr = (ulong)shmaddr)) {
 957                if (addr & (SHMLBA-1)) {
 958                        if (shmflg & SHM_RND)
 959                                addr &= ~(SHMLBA-1);       /* round down */
 960                        else
 961#ifndef __ARCH_FORCE_SHMLBA
 962                                if (addr & ~PAGE_MASK)
 963#endif
 964                                        goto out;
 965                }
 966                flags = MAP_SHARED | MAP_FIXED;
 967        } else {
 968                if ((shmflg & SHM_REMAP))
 969                        goto out;
 970
 971                flags = MAP_SHARED;
 972        }
 973
 974        if (shmflg & SHM_RDONLY) {
 975                prot = PROT_READ;
 976                acc_mode = S_IRUGO;
 977                f_mode = FMODE_READ;
 978        } else {
 979                prot = PROT_READ | PROT_WRITE;
 980                acc_mode = S_IRUGO | S_IWUGO;
 981                f_mode = FMODE_READ | FMODE_WRITE;
 982        }
 983        if (shmflg & SHM_EXEC) {
 984                prot |= PROT_EXEC;
 985                acc_mode |= S_IXUGO;
 986        }
 987
 988        /*
 989         * We cannot rely on the fs check since SYSV IPC does have an
 990         * additional creator id...
 991         */
 992        ns = current->nsproxy->ipc_ns;
 993        shp = shm_lock_check(ns, shmid);
 994        if (IS_ERR(shp)) {
 995                err = PTR_ERR(shp);
 996                goto out;
 997        }
 998
 999        err = -EACCES;
1000        if (ipcperms(ns, &shp->shm_perm, acc_mode))
1001                goto out_unlock;
1002
1003        err = security_shm_shmat(shp, shmaddr, shmflg);
1004        if (err)
1005                goto out_unlock;
1006
1007        path = shp->shm_file->f_path;
1008        path_get(&path);
1009        shp->shm_nattch++;
1010        size = i_size_read(path.dentry->d_inode);
1011        shm_unlock(shp);
1012
1013        err = -ENOMEM;
1014        sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
1015        if (!sfd)
1016                goto out_put_dentry;
1017
1018        file = alloc_file(&path, f_mode,
1019                          is_file_hugepages(shp->shm_file) ?
1020                                &shm_file_operations_huge :
1021                                &shm_file_operations);
1022        if (!file)
1023                goto out_free;
1024
1025        file->private_data = sfd;
1026        file->f_mapping = shp->shm_file->f_mapping;
1027        sfd->id = shp->shm_perm.id;
1028        sfd->ns = get_ipc_ns(ns);
1029        sfd->file = shp->shm_file;
1030        sfd->vm_ops = NULL;
1031
1032        down_write(&current->mm->mmap_sem);
1033        if (addr && !(shmflg & SHM_REMAP)) {
1034                err = -EINVAL;
1035                if (find_vma_intersection(current->mm, addr, addr + size))
1036                        goto invalid;
1037                /*
1038                 * If shm segment goes below stack, make sure there is some
1039                 * space left for the stack to grow (at least 4 pages).
1040                 */
1041                if (addr < current->mm->start_stack &&
1042                    addr > current->mm->start_stack - size - PAGE_SIZE * 5)
1043                        goto invalid;
1044        }
1045                
1046        user_addr = do_mmap (file, addr, size, prot, flags, 0);
1047        *raddr = user_addr;
1048        err = 0;
1049        if (IS_ERR_VALUE(user_addr))
1050                err = (long)user_addr;
1051invalid:
1052        up_write(&current->mm->mmap_sem);
1053
1054        fput(file);
1055
1056out_nattch:
1057        down_write(&shm_ids(ns).rw_mutex);
1058        shp = shm_lock(ns, shmid);
1059        BUG_ON(IS_ERR(shp));
1060        shp->shm_nattch--;
1061        if (shm_may_destroy(ns, shp))
1062                shm_destroy(ns, shp);
1063        else
1064                shm_unlock(shp);
1065        up_write(&shm_ids(ns).rw_mutex);
1066
1067out:
1068        return err;
1069
1070out_unlock:
1071        shm_unlock(shp);
1072        goto out;
1073
1074out_free:
1075        kfree(sfd);
1076out_put_dentry:
1077        path_put(&path);
1078        goto out_nattch;
1079}
1080
1081SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
1082{
1083        unsigned long ret;
1084        long err;
1085
1086        err = do_shmat(shmid, shmaddr, shmflg, &ret);
1087        if (err)
1088                return err;
1089        force_successful_syscall_return();
1090        return (long)ret;
1091}
1092
1093/*
1094 * detach and kill segment if marked destroyed.
1095 * The work is done in shm_close.
1096 */
1097SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
1098{
1099        struct mm_struct *mm = current->mm;
1100        struct vm_area_struct *vma;
1101        unsigned long addr = (unsigned long)shmaddr;
1102        int retval = -EINVAL;
1103#ifdef CONFIG_MMU
1104        loff_t size = 0;
1105        struct vm_area_struct *next;
1106#endif
1107
1108        if (addr & ~PAGE_MASK)
1109                return retval;
1110
1111        down_write(&mm->mmap_sem);
1112
1113        /*
1114         * This function tries to be smart and unmap shm segments that
1115         * were modified by partial mlock or munmap calls:
1116         * - It first determines the size of the shm segment that should be
1117         *   unmapped: It searches for a vma that is backed by shm and that
1118         *   started at address shmaddr. It records it's size and then unmaps
1119         *   it.
1120         * - Then it unmaps all shm vmas that started at shmaddr and that
1121         *   are within the initially determined size.
1122         * Errors from do_munmap are ignored: the function only fails if
1123         * it's called with invalid parameters or if it's called to unmap
1124         * a part of a vma. Both calls in this function are for full vmas,
1125         * the parameters are directly copied from the vma itself and always
1126         * valid - therefore do_munmap cannot fail. (famous last words?)
1127         */
1128        /*
1129         * If it had been mremap()'d, the starting address would not
1130         * match the usual checks anyway. So assume all vma's are
1131         * above the starting address given.
1132         */
1133        vma = find_vma(mm, addr);
1134
1135#ifdef CONFIG_MMU
1136        while (vma) {
1137                next = vma->vm_next;
1138
1139                /*
1140                 * Check if the starting address would match, i.e. it's
1141                 * a fragment created by mprotect() and/or munmap(), or it
1142                 * otherwise it starts at this address with no hassles.
1143                 */
1144                if ((vma->vm_ops == &shm_vm_ops) &&
1145                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
1146
1147
1148                        size = vma->vm_file->f_path.dentry->d_inode->i_size;
1149                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1150                        /*
1151                         * We discovered the size of the shm segment, so
1152                         * break out of here and fall through to the next
1153                         * loop that uses the size information to stop
1154                         * searching for matching vma's.
1155                         */
1156                        retval = 0;
1157                        vma = next;
1158                        break;
1159                }
1160                vma = next;
1161        }
1162
1163        /*
1164         * We need look no further than the maximum address a fragment
1165         * could possibly have landed at. Also cast things to loff_t to
1166         * prevent overflows and make comparisons vs. equal-width types.
1167         */
1168        size = PAGE_ALIGN(size);
1169        while (vma && (loff_t)(vma->vm_end - addr) <= size) {
1170                next = vma->vm_next;
1171
1172                /* finding a matching vma now does not alter retval */
1173                if ((vma->vm_ops == &shm_vm_ops) &&
1174                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)
1175
1176                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1177                vma = next;
1178        }
1179
1180#else /* CONFIG_MMU */
1181        /* under NOMMU conditions, the exact address to be destroyed must be
1182         * given */
1183        retval = -EINVAL;
1184        if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
1185                do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
1186                retval = 0;
1187        }
1188
1189#endif
1190
1191        up_write(&mm->mmap_sem);
1192        return retval;
1193}
1194
1195#ifdef CONFIG_PROC_FS
1196static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
1197{
1198        struct shmid_kernel *shp = it;
1199        unsigned long rss = 0, swp = 0;
1200
1201        shm_add_rss_swap(shp, &rss, &swp);
1202
1203#if BITS_PER_LONG <= 32
1204#define SIZE_SPEC "%10lu"
1205#else
1206#define SIZE_SPEC "%21lu"
1207#endif
1208
1209        return seq_printf(s,
1210                          "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1211                          "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
1212                          SIZE_SPEC " " SIZE_SPEC "\n",
1213                          shp->shm_perm.key,
1214                          shp->shm_perm.id,
1215                          shp->shm_perm.mode,
1216                          shp->shm_segsz,
1217                          shp->shm_cprid,
1218                          shp->shm_lprid,
1219                          shp->shm_nattch,
1220                          shp->shm_perm.uid,
1221                          shp->shm_perm.gid,
1222                          shp->shm_perm.cuid,
1223                          shp->shm_perm.cgid,
1224                          shp->shm_atim,
1225                          shp->shm_dtim,
1226                          shp->shm_ctim,
1227                          rss * PAGE_SIZE,
1228                          swp * PAGE_SIZE);
1229}
1230#endif
1231
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