fs/autofs4/dev-ioctl.c

   1 /*
   2  * Copyright 2008 Red Hat, Inc. All rights reserved.
   3  * Copyright 2008 Ian Kent <raven@themaw.net>
   4  *
   5  * This file is part of the Linux kernel and is made available under
   6  * the terms of the GNU General Public License, version 2, or at your
   7  * option, any later version, incorporated herein by reference.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/init.h>
  14 #include <linux/wait.h>
  15 #include <linux/namei.h>
  16 #include <linux/fcntl.h>
  17 #include <linux/file.h>
  18 #include <linux/fdtable.h>
  19 #include <linux/sched.h>
  20 #include <linux/compat.h>
  21 #include <linux/syscalls.h>
  22 #include <linux/magic.h>
  23 #include <linux/dcache.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/slab.h>
  26
  27 #include "autofs_i.h"
  28
  29 /*
  30  * This module implements an interface for routing autofs ioctl control
  31  * commands via a miscellaneous device file.
  32  *
  33  * The alternate interface is needed because we need to be able open
  34  * an ioctl file descriptor on an autofs mount that may be covered by
  35  * another mount. This situation arises when starting automount(8)
  36  * or other user space daemon which uses direct mounts or offset
  37  * mounts (used for autofs lazy mount/umount of nested mount trees),
  38  * which have been left busy at at service shutdown.
  39  */
  40
  41 #define AUTOFS_DEV_IOCTL_SIZE   sizeof(struct autofs_dev_ioctl)
  42
  43 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  44                         struct autofs_dev_ioctl *);
  45
  46 static int check_name(const char *name)
  47 {
  48         if (!strchr(name, '/'))
  49                 return -EINVAL;
  50         return 0;
  51 }
  52
  53 /*
  54  * Check a string doesn't overrun the chunk of
  55  * memory we copied from user land.
  56  */
  57 static int invalid_str(char *str, size_t size)
  58 {
  59         if (memchr(str, 0, size))
  60                 return 0;
  61         return -EINVAL;
  62 }
  63
  64 /*
  65  * Check that the user compiled against correct version of autofs
  66  * misc device code.
  67  *
  68  * As well as checking the version compatibility this always copies
  69  * the kernel interface version out.
  70  */
  71 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  72 {
  73         int err = 0;
  74
  75         if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
  76             (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
  77                 AUTOFS_WARN("ioctl control interface version mismatch: "
  78                      "kernel(%u.%u), user(%u.%u), cmd(%d)",
  79                      AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  80                      AUTOFS_DEV_IOCTL_VERSION_MINOR,
  81                      param->ver_major, param->ver_minor, cmd);
  82                 err = -EINVAL;
  83         }
  84
  85         /* Fill in the kernel version. */
  86         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  87         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  88
  89         return err;
  90 }
  91
  92 /*
  93  * Copy parameter control struct, including a possible path allocated
  94  * at the end of the struct.
  95  */
  96 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  97 {
  98         struct autofs_dev_ioctl tmp, *res;
  99
 100         if (copy_from_user(&tmp, in, sizeof(tmp)))
 101                 return ERR_PTR(-EFAULT);
 102
 103         if (tmp.size < sizeof(tmp))
 104                 return ERR_PTR(-EINVAL);
 105
 106         res = memdup_user(in, tmp.size);
 107         if (!IS_ERR(res))
 108                 res->size = tmp.size;
 109
 110         return res;
 111 }
 112
 113 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 114 {
 115         kfree(param);
 116         return;
 117 }
 118
 119 /*
 120  * Check sanity of parameter control fields and if a path is present
 121  * check that it is terminated and contains at least one "/".
 122  */
 123 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 124 {
 125         int err;
 126
 127         err = check_dev_ioctl_version(cmd, param);
 128         if (err) {
 129                 AUTOFS_WARN("invalid device control module version "
 130                      "supplied for cmd(0x%08x)", cmd);
 131                 goto out;
 132         }
 133
 134         if (param->size > sizeof(*param)) {
 135                 err = invalid_str(param->path, param->size - sizeof(*param));
 136                 if (err) {
 137                         AUTOFS_WARN(
 138                           "path string terminator missing for cmd(0x%08x)",
 139                           cmd);
 140                         goto out;
 141                 }
 142
 143                 err = check_name(param->path);
 144                 if (err) {
 145                         AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 146                                     cmd);
 147                         goto out;
 148                 }
 149         }
 150
 151         err = 0;
 152 out:
 153         return err;
 154 }
 155
 156 /*
 157  * Get the autofs super block info struct from the file opened on
 158  * the autofs mount point.
 159  */
 160 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 161 {
 162         struct autofs_sb_info *sbi = NULL;
 163         struct inode *inode;
 164
 165         if (f) {
 166                 inode = file_inode(f);
 167                 sbi = autofs4_sbi(inode->i_sb);
 168         }
 169         return sbi;
 170 }
 171
 172 /* Return autofs module protocol version */
 173 static int autofs_dev_ioctl_protover(struct file *fp,
 174                                      struct autofs_sb_info *sbi,
 175                                      struct autofs_dev_ioctl *param)
 176 {
 177         param->protover.version = sbi->version;
 178         return 0;
 179 }
 180
 181 /* Return autofs module protocol sub version */
 182 static int autofs_dev_ioctl_protosubver(struct file *fp,
 183                                         struct autofs_sb_info *sbi,
 184                                         struct autofs_dev_ioctl *param)
 185 {
 186         param->protosubver.sub_version = sbi->sub_version;
 187         return 0;
 188 }
 189
 190 /* Find the topmost mount satisfying test() */
 191 static int find_autofs_mount(const char *pathname,
 192                              struct path *res,
 193                              int test(struct path *path, void *data),
 194                              void *data)
 195 {
 196         struct path path;
 197         int err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 198         if (err)
 199                 return err;
 200         err = -ENOENT;
 201         while (path.dentry == path.mnt->mnt_root) {
 202                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 203                         if (test(&path, data)) {
 204                                 path_get(&path);
 205                                 *res = path;
 206                                 err = 0;
 207                                 break;
 208                         }
 209                 }
 210                 if (!follow_up(&path))
 211                         break;
 212         }
 213         path_put(&path);
 214         return err;
 215 }
 216
 217 static int test_by_dev(struct path *path, void *p)
 218 {
 219         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 220 }
 221
 222 static int test_by_type(struct path *path, void *p)
 223 {
 224         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 225         return ino && ino->sbi->type & *(unsigned *)p;
 226 }
 227
 228 /*
 229  * Open a file descriptor on the autofs mount point corresponding
 230  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 231  */
 232 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 233 {
 234         int err, fd;
 235
 236         fd = get_unused_fd_flags(O_CLOEXEC);
 237         if (likely(fd >= 0)) {
 238                 struct file *filp;
 239                 struct path path;
 240
 241                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 242                 if (err)
 243                         goto out;
 244
 245                 /*
 246                  * Find autofs super block that has the device number
 247                  * corresponding to the autofs fs we want to open.
 248                  */
 249
 250                 filp = dentry_open(&path, O_RDONLY, current_cred());
 251                 path_put(&path);
 252                 if (IS_ERR(filp)) {
 253                         err = PTR_ERR(filp);
 254                         goto out;
 255                 }
 256
 257                 fd_install(fd, filp);
 258         }
 259
 260         return fd;
 261
 262 out:
 263         put_unused_fd(fd);
 264         return err;
 265 }
 266
 267 /* Open a file descriptor on an autofs mount point */
 268 static int autofs_dev_ioctl_openmount(struct file *fp,
 269                                       struct autofs_sb_info *sbi,
 270                                       struct autofs_dev_ioctl *param)
 271 {
 272         const char *path;
 273         dev_t devid;
 274         int err, fd;
 275
 276         /* param->path has already been checked */
 277         if (!param->openmount.devid)
 278                 return -EINVAL;
 279
 280         param->ioctlfd = -1;
 281
 282         path = param->path;
 283         devid = new_decode_dev(param->openmount.devid);
 284
 285         err = 0;
 286         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 287         if (unlikely(fd < 0)) {
 288                 err = fd;
 289                 goto out;
 290         }
 291
 292         param->ioctlfd = fd;
 293 out:
 294         return err;
 295 }
 296
 297 /* Close file descriptor allocated above (user can also use close(2)). */
 298 static int autofs_dev_ioctl_closemount(struct file *fp,
 299                                        struct autofs_sb_info *sbi,
 300                                        struct autofs_dev_ioctl *param)
 301 {
 302         return sys_close(param->ioctlfd);
 303 }
 304
 305 /*
 306  * Send "ready" status for an existing wait (either a mount or an expire
 307  * request).
 308  */
 309 static int autofs_dev_ioctl_ready(struct file *fp,
 310                                   struct autofs_sb_info *sbi,
 311                                   struct autofs_dev_ioctl *param)
 312 {
 313         autofs_wqt_t token;
 314
 315         token = (autofs_wqt_t) param->ready.token;
 316         return autofs4_wait_release(sbi, token, 0);
 317 }
 318
 319 /*
 320  * Send "fail" status for an existing wait (either a mount or an expire
 321  * request).
 322  */
 323 static int autofs_dev_ioctl_fail(struct file *fp,
 324                                  struct autofs_sb_info *sbi,
 325                                  struct autofs_dev_ioctl *param)
 326 {
 327         autofs_wqt_t token;
 328         int status;
 329
 330         token = (autofs_wqt_t) param->fail.token;
 331         status = param->fail.status ? param->fail.status : -ENOENT;
 332         return autofs4_wait_release(sbi, token, status);
 333 }
 334
 335 /*
 336  * Set the pipe fd for kernel communication to the daemon.
 337  *
 338  * Normally this is set at mount using an option but if we
 339  * are reconnecting to a busy mount then we need to use this
 340  * to tell the autofs mount about the new kernel pipe fd. In
 341  * order to protect mounts against incorrectly setting the
 342  * pipefd we also require that the autofs mount be catatonic.
 343  *
 344  * This also sets the process group id used to identify the
 345  * controlling process (eg. the owning automount(8) daemon).
 346  */
 347 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 348                                       struct autofs_sb_info *sbi,
 349                                       struct autofs_dev_ioctl *param)
 350 {
 351         int pipefd;
 352         int err = 0;
 353
 354         if (param->setpipefd.pipefd == -1)
 355                 return -EINVAL;
 356
 357         pipefd = param->setpipefd.pipefd;
 358
 359         mutex_lock(&sbi->wq_mutex);
 360         if (!sbi->catatonic) {
 361                 mutex_unlock(&sbi->wq_mutex);
 362                 return -EBUSY;
 363         } else {
 364                 struct file *pipe = fget(pipefd);
 365                 if (!pipe) {
 366                         err = -EBADF;
 367                         goto out;
 368                 }
 369                 if (autofs_prepare_pipe(pipe) < 0) {
 370                         err = -EPIPE;
 371                         fput(pipe);
 372                         goto out;
 373                 }
 374                 sbi->oz_pgrp = task_pgrp_nr(current);
 375                 sbi->pipefd = pipefd;
 376                 sbi->pipe = pipe;
 377                 sbi->catatonic = 0;
 378         }
 379 out:
 380         mutex_unlock(&sbi->wq_mutex);
 381         return err;
 382 }
 383
 384 /*
 385  * Make the autofs mount point catatonic, no longer responsive to
 386  * mount requests. Also closes the kernel pipe file descriptor.
 387  */
 388 static int autofs_dev_ioctl_catatonic(struct file *fp,
 389                                       struct autofs_sb_info *sbi,
 390                                       struct autofs_dev_ioctl *param)
 391 {
 392         autofs4_catatonic_mode(sbi);
 393         return 0;
 394 }
 395
 396 /* Set the autofs mount timeout */
 397 static int autofs_dev_ioctl_timeout(struct file *fp,
 398                                     struct autofs_sb_info *sbi,
 399                                     struct autofs_dev_ioctl *param)
 400 {
 401         unsigned long timeout;
 402
 403         timeout = param->timeout.timeout;
 404         param->timeout.timeout = sbi->exp_timeout / HZ;
 405         sbi->exp_timeout = timeout * HZ;
 406         return 0;
 407 }
 408
 409 /*
 410  * Return the uid and gid of the last request for the mount
 411  *
 412  * When reconstructing an autofs mount tree with active mounts
 413  * we need to re-connect to mounts that may have used the original
 414  * process uid and gid (or string variations of them) for mount
 415  * lookups within the map entry.
 416  */
 417 static int autofs_dev_ioctl_requester(struct file *fp,
 418                                       struct autofs_sb_info *sbi,
 419                                       struct autofs_dev_ioctl *param)
 420 {
 421         struct autofs_info *ino;
 422         struct path path;
 423         dev_t devid;
 424         int err = -ENOENT;
 425
 426         if (param->size <= sizeof(*param)) {
 427                 err = -EINVAL;
 428                 goto out;
 429         }
 430
 431         devid = sbi->sb->s_dev;
 432
 433         param->requester.uid = param->requester.gid = -1;
 434
 435         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 436         if (err)
 437                 goto out;
 438
 439         ino = autofs4_dentry_ino(path.dentry);
 440         if (ino) {
 441                 err = 0;
 442                 autofs4_expire_wait(path.dentry);
 443                 spin_lock(&sbi->fs_lock);
 444                 param->requester.uid = from_kuid_munged(current_user_ns(), ino->uid);
 445                 param->requester.gid = from_kgid_munged(current_user_ns(), ino->gid);
 446                 spin_unlock(&sbi->fs_lock);
 447         }
 448         path_put(&path);
 449 out:
 450         return err;
 451 }
 452
 453 /*
 454  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 455  * more that can be done.
 456  */
 457 static int autofs_dev_ioctl_expire(struct file *fp,
 458                                    struct autofs_sb_info *sbi,
 459                                    struct autofs_dev_ioctl *param)
 460 {
 461         struct vfsmount *mnt;
 462         int how;
 463
 464         how = param->expire.how;
 465         mnt = fp->f_path.mnt;
 466
 467         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 468 }
 469
 470 /* Check if autofs mount point is in use */
 471 static int autofs_dev_ioctl_askumount(struct file *fp,
 472                                       struct autofs_sb_info *sbi,
 473                                       struct autofs_dev_ioctl *param)
 474 {
 475         param->askumount.may_umount = 0;
 476         if (may_umount(fp->f_path.mnt))
 477                 param->askumount.may_umount = 1;
 478         return 0;
 479 }
 480
 481 /*
 482  * Check if the given path is a mountpoint.
 483  *
 484  * If we are supplied with the file descriptor of an autofs
 485  * mount we're looking for a specific mount. In this case
 486  * the path is considered a mountpoint if it is itself a
 487  * mountpoint or contains a mount, such as a multi-mount
 488  * without a root mount. In this case we return 1 if the
 489  * path is a mount point and the super magic of the covering
 490  * mount if there is one or 0 if it isn't a mountpoint.
 491  *
 492  * If we aren't supplied with a file descriptor then we
 493  * lookup the path and check if it is the root of a mount.
 494  * If a type is given we are looking for a particular autofs
 495  * mount and if we don't find a match we return fail. If the
 496  * located path is the root of a mount we return 1 along with
 497  * the super magic of the mount or 0 otherwise.
 498  *
 499  * In both cases the the device number (as returned by
 500  * new_encode_dev()) is also returned.
 501  */
 502 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 503                                          struct autofs_sb_info *sbi,
 504                                          struct autofs_dev_ioctl *param)
 505 {
 506         struct path path;
 507         const char *name;
 508         unsigned int type;
 509         unsigned int devid, magic;
 510         int err = -ENOENT;
 511
 512         if (param->size <= sizeof(*param)) {
 513                 err = -EINVAL;
 514                 goto out;
 515         }
 516
 517         name = param->path;
 518         type = param->ismountpoint.in.type;
 519
 520         param->ismountpoint.out.devid = devid = 0;
 521         param->ismountpoint.out.magic = magic = 0;
 522
 523         if (!fp || param->ioctlfd == -1) {
 524                 if (autofs_type_any(type))
 525                         err = kern_path_mountpoint(AT_FDCWD,
 526                                                    name, &path, LOOKUP_FOLLOW);
 527                 else
 528                         err = find_autofs_mount(name, &path,
 529                                                 test_by_type, &type);
 530                 if (err)
 531                         goto out;
 532                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 533                 err = 0;
 534                 if (path.mnt->mnt_root == path.dentry) {
 535                         err = 1;
 536                         magic = path.dentry->d_sb->s_magic;
 537                 }
 538         } else {
 539                 dev_t dev = sbi->sb->s_dev;
 540
 541                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 542                 if (err)
 543                         goto out;
 544
 545                 devid = new_encode_dev(dev);
 546
 547                 err = have_submounts(path.dentry);
 548
 549                 if (follow_down_one(&path))
 550                         magic = path.dentry->d_sb->s_magic;
 551         }
 552
 553         param->ismountpoint.out.devid = devid;
 554         param->ismountpoint.out.magic = magic;
 555         path_put(&path);
 556 out:
 557         return err;
 558 }
 559
 560 /*
 561  * Our range of ioctl numbers isn't 0 based so we need to shift
 562  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 563  * lookup.
 564  */
 565 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 566
 567 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 568 {
 569         static struct {
 570                 int cmd;
 571                 ioctl_fn fn;
 572         } _ioctls[] = {
 573                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 574                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 575                          autofs_dev_ioctl_protover},
 576                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 577                          autofs_dev_ioctl_protosubver},
 578                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 579                          autofs_dev_ioctl_openmount},
 580                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 581                          autofs_dev_ioctl_closemount},
 582                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 583                          autofs_dev_ioctl_ready},
 584                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 585                          autofs_dev_ioctl_fail},
 586                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 587                          autofs_dev_ioctl_setpipefd},
 588                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 589                          autofs_dev_ioctl_catatonic},
 590                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 591                          autofs_dev_ioctl_timeout},
 592                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 593                          autofs_dev_ioctl_requester},
 594                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 595                          autofs_dev_ioctl_expire},
 596                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 597                          autofs_dev_ioctl_askumount},
 598                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 599                          autofs_dev_ioctl_ismountpoint}
 600         };
 601         unsigned int idx = cmd_idx(cmd);
 602
 603         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 604 }
 605
 606 /* ioctl dispatcher */
 607 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 608 {
 609         struct autofs_dev_ioctl *param;
 610         struct file *fp;
 611         struct autofs_sb_info *sbi;
 612         unsigned int cmd_first, cmd;
 613         ioctl_fn fn = NULL;
 614         int err = 0;
 615
 616         /* only root can play with this */
 617         if (!capable(CAP_SYS_ADMIN))
 618                 return -EPERM;
 619
 620         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 621         cmd = _IOC_NR(command);
 622
 623         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 624             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 625                 return -ENOTTY;
 626         }
 627
 628         /* Copy the parameters into kernel space. */
 629         param = copy_dev_ioctl(user);
 630         if (IS_ERR(param))
 631                 return PTR_ERR(param);
 632
 633         err = validate_dev_ioctl(command, param);
 634         if (err)
 635                 goto out;
 636
 637         /* The validate routine above always sets the version */
 638         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 639                 goto done;
 640
 641         fn = lookup_dev_ioctl(cmd);
 642         if (!fn) {
 643                 AUTOFS_WARN("unknown command 0x%08x", command);
 644                 return -ENOTTY;
 645         }
 646
 647         fp = NULL;
 648         sbi = NULL;
 649
 650         /*
 651          * For obvious reasons the openmount can't have a file
 652          * descriptor yet. We don't take a reference to the
 653          * file during close to allow for immediate release.
 654          */
 655         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 656             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 657                 fp = fget(param->ioctlfd);
 658                 if (!fp) {
 659                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 660                                 goto cont;
 661                         err = -EBADF;
 662                         goto out;
 663                 }
 664
 665                 if (!fp->f_op) {
 666                         err = -ENOTTY;
 667                         fput(fp);
 668                         goto out;
 669                 }
 670
 671                 sbi = autofs_dev_ioctl_sbi(fp);
 672                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 673                         err = -EINVAL;
 674                         fput(fp);
 675                         goto out;
 676                 }
 677
 678                 /*
 679                  * Admin needs to be able to set the mount catatonic in
 680                  * order to be able to perform the re-open.
 681                  */
 682                 if (!autofs4_oz_mode(sbi) &&
 683                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 684                         err = -EACCES;
 685                         fput(fp);
 686                         goto out;
 687                 }
 688         }
 689 cont:
 690         err = fn(fp, sbi, param);
 691
 692         if (fp)
 693                 fput(fp);
 694 done:
 695         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 696                 err = -EFAULT;
 697 out:
 698         free_dev_ioctl(param);
 699         return err;
 700 }
 701
 702 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 703 {
 704         int err;
 705         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 706         return (long) err;
 707 }
 708
 709 #ifdef CONFIG_COMPAT
 710 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 711 {
 712         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 713 }
 714 #else
 715 #define autofs_dev_ioctl_compat NULL
 716 #endif
 717
 718 static const struct file_operations _dev_ioctl_fops = {
 719         .unlocked_ioctl  = autofs_dev_ioctl,
 720         .compat_ioctl = autofs_dev_ioctl_compat,
 721         .owner   = THIS_MODULE,
 722         .llseek = noop_llseek,
 723 };
 724
 725 static struct miscdevice _autofs_dev_ioctl_misc = {
 726         .minor          = AUTOFS_MINOR,
 727         .name           = AUTOFS_DEVICE_NAME,
 728         .fops           = &_dev_ioctl_fops
 729 };
 730
 731 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 732 MODULE_ALIAS("devname:autofs");
 733
 734 /* Register/deregister misc character device */
 735 int autofs_dev_ioctl_init(void)
 736 {
 737         int r;
 738
 739         r = misc_register(&_autofs_dev_ioctl_misc);
 740         if (r) {
 741                 AUTOFS_ERROR("misc_register failed for control device");
 742                 return r;
 743         }
 744
 745         return 0;
 746 }
 747
 748 void autofs_dev_ioctl_exit(void)
 749 {
 750         misc_deregister(&_autofs_dev_ioctl_misc);
 751         return;
 752 }
 753