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
  26 #include "autofs_i.h"
  27
  28 /*
  29  * This module implements an interface for routing autofs ioctl control
  30  * commands via a miscellaneous device file.
  31  *
  32  * The alternate interface is needed because we need to be able open
  33  * an ioctl file descriptor on an autofs mount that may be covered by
  34  * another mount. This situation arises when starting automount(8)
  35  * or other user space daemon which uses direct mounts or offset
  36  * mounts (used for autofs lazy mount/umount of nested mount trees),
  37  * which have been left busy at at service shutdown.
  38  */
  39
  40 #define AUTOFS_DEV_IOCTL_SIZE   sizeof(struct autofs_dev_ioctl)
  41
  42 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  43                         struct autofs_dev_ioctl *);
  44
  45 static int check_name(const char *name)
  46 {
  47         if (!strchr(name, '/'))
  48                 return -EINVAL;
  49         return 0;
  50 }
  51
  52 /*
  53  * Check a string doesn't overrun the chunk of
  54  * memory we copied from user land.
  55  */
  56 static int invalid_str(char *str, size_t size)
  57 {
  58         if (memchr(str, 0, size))
  59                 return 0;
  60         return -EINVAL;
  61 }
  62
  63 /*
  64  * Check that the user compiled against correct version of autofs
  65  * misc device code.
  66  *
  67  * As well as checking the version compatibility this always copies
  68  * the kernel interface version out.
  69  */
  70 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  71 {
  72         int err = 0;
  73
  74         if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
  75             (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
  76                 AUTOFS_WARN("ioctl control interface version mismatch: "
  77                      "kernel(%u.%u), user(%u.%u), cmd(%d)",
  78                      AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  79                      AUTOFS_DEV_IOCTL_VERSION_MINOR,
  80                      param->ver_major, param->ver_minor, cmd);
  81                 err = -EINVAL;
  82         }
  83
  84         /* Fill in the kernel version. */
  85         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  86         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  87
  88         return err;
  89 }
  90
  91 /*
  92  * Copy parameter control struct, including a possible path allocated
  93  * at the end of the struct.
  94  */
  95 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  96 {
  97         struct autofs_dev_ioctl tmp, *ads;
  98
  99         if (copy_from_user(&tmp, in, sizeof(tmp)))
 100                 return ERR_PTR(-EFAULT);
 101
 102         if (tmp.size < sizeof(tmp))
 103                 return ERR_PTR(-EINVAL);
 104
 105         ads = kmalloc(tmp.size, GFP_KERNEL);
 106         if (!ads)
 107                 return ERR_PTR(-ENOMEM);
 108
 109         if (copy_from_user(ads, in, tmp.size)) {
 110                 kfree(ads);
 111                 return ERR_PTR(-EFAULT);
 112         }
 113
 114         return ads;
 115 }
 116
 117 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 118 {
 119         kfree(param);
 120         return;
 121 }
 122
 123 /*
 124  * Check sanity of parameter control fields and if a path is present
 125  * check that it is terminated and contains at least one "/".
 126  */
 127 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 128 {
 129         int err;
 130
 131         err = check_dev_ioctl_version(cmd, param);
 132         if (err) {
 133                 AUTOFS_WARN("invalid device control module version "
 134                      "supplied for cmd(0x%08x)", cmd);
 135                 goto out;
 136         }
 137
 138         if (param->size > sizeof(*param)) {
 139                 err = invalid_str(param->path, param->size - sizeof(*param));
 140                 if (err) {
 141                         AUTOFS_WARN(
 142                           "path string terminator missing for cmd(0x%08x)",
 143                           cmd);
 144                         goto out;
 145                 }
 146
 147                 err = check_name(param->path);
 148                 if (err) {
 149                         AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 150                                     cmd);
 151                         goto out;
 152                 }
 153         }
 154
 155         err = 0;
 156 out:
 157         return err;
 158 }
 159
 160 /*
 161  * Get the autofs super block info struct from the file opened on
 162  * the autofs mount point.
 163  */
 164 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 165 {
 166         struct autofs_sb_info *sbi = NULL;
 167         struct inode *inode;
 168
 169         if (f) {
 170                 inode = f->f_path.dentry->d_inode;
 171                 sbi = autofs4_sbi(inode->i_sb);
 172         }
 173         return sbi;
 174 }
 175
 176 /* Return autofs module protocol version */
 177 static int autofs_dev_ioctl_protover(struct file *fp,
 178                                      struct autofs_sb_info *sbi,
 179                                      struct autofs_dev_ioctl *param)
 180 {
 181         param->protover.version = sbi->version;
 182         return 0;
 183 }
 184
 185 /* Return autofs module protocol sub version */
 186 static int autofs_dev_ioctl_protosubver(struct file *fp,
 187                                         struct autofs_sb_info *sbi,
 188                                         struct autofs_dev_ioctl *param)
 189 {
 190         param->protosubver.sub_version = sbi->sub_version;
 191         return 0;
 192 }
 193
 194 static int find_autofs_mount(const char *pathname,
 195                              struct path *res,
 196                              int test(struct path *path, void *data),
 197                              void *data)
 198 {
 199         struct path path;
 200         int err = kern_path(pathname, 0, &path);
 201         if (err)
 202                 return err;
 203         err = -ENOENT;
 204         while (path.dentry == path.mnt->mnt_root) {
 205                 if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 206                         if (test(&path, data)) {
 207                                 path_get(&path);
 208                                 if (!err) /* already found some */
 209                                         path_put(res);
 210                                 *res = path;
 211                                 err = 0;
 212                         }
 213                 }
 214                 if (!follow_up(&path))
 215                         break;
 216         }
 217         path_put(&path);
 218         return err;
 219 }
 220
 221 static int test_by_dev(struct path *path, void *p)
 222 {
 223         return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
 224 }
 225
 226 static int test_by_type(struct path *path, void *p)
 227 {
 228         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 229         return ino && ino->sbi->type & *(unsigned *)p;
 230 }
 231
 232 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
 233 {
 234         struct files_struct *files = current->files;
 235         struct fdtable *fdt;
 236
 237         spin_lock(&files->file_lock);
 238         fdt = files_fdtable(files);
 239         BUG_ON(fdt->fd[fd] != NULL);
 240         rcu_assign_pointer(fdt->fd[fd], file);
 241         FD_SET(fd, fdt->close_on_exec);
 242         spin_unlock(&files->file_lock);
 243 }
 244
 245
 246 /*
 247  * Open a file descriptor on the autofs mount point corresponding
 248  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 249  */
 250 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 251 {
 252         int err, fd;
 253
 254         fd = get_unused_fd();
 255         if (likely(fd >= 0)) {
 256                 struct file *filp;
 257                 struct path path;
 258
 259                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 260                 if (err)
 261                         goto out;
 262
 263                 /*
 264                  * Find autofs super block that has the device number
 265                  * corresponding to the autofs fs we want to open.
 266                  */
 267
 268                 filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
 269                                    current_cred());
 270                 if (IS_ERR(filp)) {
 271                         err = PTR_ERR(filp);
 272                         goto out;
 273                 }
 274
 275                 autofs_dev_ioctl_fd_install(fd, filp);
 276         }
 277
 278         return fd;
 279
 280 out:
 281         put_unused_fd(fd);
 282         return err;
 283 }
 284
 285 /* Open a file descriptor on an autofs mount point */
 286 static int autofs_dev_ioctl_openmount(struct file *fp,
 287                                       struct autofs_sb_info *sbi,
 288                                       struct autofs_dev_ioctl *param)
 289 {
 290         const char *path;
 291         dev_t devid;
 292         int err, fd;
 293
 294         /* param->path has already been checked */
 295         if (!param->openmount.devid)
 296                 return -EINVAL;
 297
 298         param->ioctlfd = -1;
 299
 300         path = param->path;
 301         devid = new_decode_dev(param->openmount.devid);
 302
 303         err = 0;
 304         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 305         if (unlikely(fd < 0)) {
 306                 err = fd;
 307                 goto out;
 308         }
 309
 310         param->ioctlfd = fd;
 311 out:
 312         return err;
 313 }
 314
 315 /* Close file descriptor allocated above (user can also use close(2)). */
 316 static int autofs_dev_ioctl_closemount(struct file *fp,
 317                                        struct autofs_sb_info *sbi,
 318                                        struct autofs_dev_ioctl *param)
 319 {
 320         return sys_close(param->ioctlfd);
 321 }
 322
 323 /*
 324  * Send "ready" status for an existing wait (either a mount or an expire
 325  * request).
 326  */
 327 static int autofs_dev_ioctl_ready(struct file *fp,
 328                                   struct autofs_sb_info *sbi,
 329                                   struct autofs_dev_ioctl *param)
 330 {
 331         autofs_wqt_t token;
 332
 333         token = (autofs_wqt_t) param->ready.token;
 334         return autofs4_wait_release(sbi, token, 0);
 335 }
 336
 337 /*
 338  * Send "fail" status for an existing wait (either a mount or an expire
 339  * request).
 340  */
 341 static int autofs_dev_ioctl_fail(struct file *fp,
 342                                  struct autofs_sb_info *sbi,
 343                                  struct autofs_dev_ioctl *param)
 344 {
 345         autofs_wqt_t token;
 346         int status;
 347
 348         token = (autofs_wqt_t) param->fail.token;
 349         status = param->fail.status ? param->fail.status : -ENOENT;
 350         return autofs4_wait_release(sbi, token, status);
 351 }
 352
 353 /*
 354  * Set the pipe fd for kernel communication to the daemon.
 355  *
 356  * Normally this is set at mount using an option but if we
 357  * are reconnecting to a busy mount then we need to use this
 358  * to tell the autofs mount about the new kernel pipe fd. In
 359  * order to protect mounts against incorrectly setting the
 360  * pipefd we also require that the autofs mount be catatonic.
 361  *
 362  * This also sets the process group id used to identify the
 363  * controlling process (eg. the owning automount(8) daemon).
 364  */
 365 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 366                                       struct autofs_sb_info *sbi,
 367                                       struct autofs_dev_ioctl *param)
 368 {
 369         int pipefd;
 370         int err = 0;
 371
 372         if (param->setpipefd.pipefd == -1)
 373                 return -EINVAL;
 374
 375         pipefd = param->setpipefd.pipefd;
 376
 377         mutex_lock(&sbi->wq_mutex);
 378         if (!sbi->catatonic) {
 379                 mutex_unlock(&sbi->wq_mutex);
 380                 return -EBUSY;
 381         } else {
 382                 struct file *pipe = fget(pipefd);
 383                 if (!pipe->f_op || !pipe->f_op->write) {
 384                         err = -EPIPE;
 385                         fput(pipe);
 386                         goto out;
 387                 }
 388                 sbi->oz_pgrp = task_pgrp_nr(current);
 389                 sbi->pipefd = pipefd;
 390                 sbi->pipe = pipe;
 391                 sbi->catatonic = 0;
 392         }
 393 out:
 394         mutex_unlock(&sbi->wq_mutex);
 395         return err;
 396 }
 397
 398 /*
 399  * Make the autofs mount point catatonic, no longer responsive to
 400  * mount requests. Also closes the kernel pipe file descriptor.
 401  */
 402 static int autofs_dev_ioctl_catatonic(struct file *fp,
 403                                       struct autofs_sb_info *sbi,
 404                                       struct autofs_dev_ioctl *param)
 405 {
 406         autofs4_catatonic_mode(sbi);
 407         return 0;
 408 }
 409
 410 /* Set the autofs mount timeout */
 411 static int autofs_dev_ioctl_timeout(struct file *fp,
 412                                     struct autofs_sb_info *sbi,
 413                                     struct autofs_dev_ioctl *param)
 414 {
 415         unsigned long timeout;
 416
 417         timeout = param->timeout.timeout;
 418         param->timeout.timeout = sbi->exp_timeout / HZ;
 419         sbi->exp_timeout = timeout * HZ;
 420         return 0;
 421 }
 422
 423 /*
 424  * Return the uid and gid of the last request for the mount
 425  *
 426  * When reconstructing an autofs mount tree with active mounts
 427  * we need to re-connect to mounts that may have used the original
 428  * process uid and gid (or string variations of them) for mount
 429  * lookups within the map entry.
 430  */
 431 static int autofs_dev_ioctl_requester(struct file *fp,
 432                                       struct autofs_sb_info *sbi,
 433                                       struct autofs_dev_ioctl *param)
 434 {
 435         struct autofs_info *ino;
 436         struct path path;
 437         dev_t devid;
 438         int err = -ENOENT;
 439
 440         if (param->size <= sizeof(*param)) {
 441                 err = -EINVAL;
 442                 goto out;
 443         }
 444
 445         devid = sbi->sb->s_dev;
 446
 447         param->requester.uid = param->requester.gid = -1;
 448
 449         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 450         if (err)
 451                 goto out;
 452
 453         ino = autofs4_dentry_ino(path.dentry);
 454         if (ino) {
 455                 err = 0;
 456                 autofs4_expire_wait(path.dentry);
 457                 spin_lock(&sbi->fs_lock);
 458                 param->requester.uid = ino->uid;
 459                 param->requester.gid = ino->gid;
 460                 spin_unlock(&sbi->fs_lock);
 461         }
 462         path_put(&path);
 463 out:
 464         return err;
 465 }
 466
 467 /*
 468  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 469  * more that can be done.
 470  */
 471 static int autofs_dev_ioctl_expire(struct file *fp,
 472                                    struct autofs_sb_info *sbi,
 473                                    struct autofs_dev_ioctl *param)
 474 {
 475         struct vfsmount *mnt;
 476         int how;
 477
 478         how = param->expire.how;
 479         mnt = fp->f_path.mnt;
 480
 481         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 482 }
 483
 484 /* Check if autofs mount point is in use */
 485 static int autofs_dev_ioctl_askumount(struct file *fp,
 486                                       struct autofs_sb_info *sbi,
 487                                       struct autofs_dev_ioctl *param)
 488 {
 489         param->askumount.may_umount = 0;
 490         if (may_umount(fp->f_path.mnt))
 491                 param->askumount.may_umount = 1;
 492         return 0;
 493 }
 494
 495 /*
 496  * Check if the given path is a mountpoint.
 497  *
 498  * If we are supplied with the file descriptor of an autofs
 499  * mount we're looking for a specific mount. In this case
 500  * the path is considered a mountpoint if it is itself a
 501  * mountpoint or contains a mount, such as a multi-mount
 502  * without a root mount. In this case we return 1 if the
 503  * path is a mount point and the super magic of the covering
 504  * mount if there is one or 0 if it isn't a mountpoint.
 505  *
 506  * If we aren't supplied with a file descriptor then we
 507  * lookup the nameidata of the path and check if it is the
 508  * root of a mount. If a type is given we are looking for
 509  * a particular autofs mount and if we don't find a match
 510  * we return fail. If the located nameidata path is the
 511  * root of a mount we return 1 along with the super magic
 512  * of the mount or 0 otherwise.
 513  *
 514  * In both cases the the device number (as returned by
 515  * new_encode_dev()) is also returned.
 516  */
 517 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 518                                          struct autofs_sb_info *sbi,
 519                                          struct autofs_dev_ioctl *param)
 520 {
 521         struct path path;
 522         const char *name;
 523         unsigned int type;
 524         unsigned int devid, magic;
 525         int err = -ENOENT;
 526
 527         if (param->size <= sizeof(*param)) {
 528                 err = -EINVAL;
 529                 goto out;
 530         }
 531
 532         name = param->path;
 533         type = param->ismountpoint.in.type;
 534
 535         param->ismountpoint.out.devid = devid = 0;
 536         param->ismountpoint.out.magic = magic = 0;
 537
 538         if (!fp || param->ioctlfd == -1) {
 539                 if (autofs_type_any(type))
 540                         err = kern_path(name, LOOKUP_FOLLOW, &path);
 541                 else
 542                         err = find_autofs_mount(name, &path, test_by_type, &type);
 543                 if (err)
 544                         goto out;
 545                 devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
 546                 err = 0;
 547                 if (path.dentry->d_inode &&
 548                     path.mnt->mnt_root == path.dentry) {
 549                         err = 1;
 550                         magic = path.dentry->d_inode->i_sb->s_magic;
 551                 }
 552         } else {
 553                 dev_t dev = sbi->sb->s_dev;
 554
 555                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 556                 if (err)
 557                         goto out;
 558
 559                 devid = new_encode_dev(dev);
 560
 561                 err = have_submounts(path.dentry);
 562
 563                 if (path.mnt->mnt_mountpoint != path.mnt->mnt_root) {
 564                         if (follow_down(&path))
 565                                 magic = path.mnt->mnt_sb->s_magic;
 566                 }
 567         }
 568
 569         param->ismountpoint.out.devid = devid;
 570         param->ismountpoint.out.magic = magic;
 571         path_put(&path);
 572 out:
 573         return err;
 574 }
 575
 576 /*
 577  * Our range of ioctl numbers isn't 0 based so we need to shift
 578  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 579  * lookup.
 580  */
 581 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 582
 583 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 584 {
 585         static struct {
 586                 int cmd;
 587                 ioctl_fn fn;
 588         } _ioctls[] = {
 589                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 590                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 591                          autofs_dev_ioctl_protover},
 592                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 593                          autofs_dev_ioctl_protosubver},
 594                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 595                          autofs_dev_ioctl_openmount},
 596                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 597                          autofs_dev_ioctl_closemount},
 598                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 599                          autofs_dev_ioctl_ready},
 600                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 601                          autofs_dev_ioctl_fail},
 602                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 603                          autofs_dev_ioctl_setpipefd},
 604                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 605                          autofs_dev_ioctl_catatonic},
 606                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 607                          autofs_dev_ioctl_timeout},
 608                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 609                          autofs_dev_ioctl_requester},
 610                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 611                          autofs_dev_ioctl_expire},
 612                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 613                          autofs_dev_ioctl_askumount},
 614                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 615                          autofs_dev_ioctl_ismountpoint}
 616         };
 617         unsigned int idx = cmd_idx(cmd);
 618
 619         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 620 }
 621
 622 /* ioctl dispatcher */
 623 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 624 {
 625         struct autofs_dev_ioctl *param;
 626         struct file *fp;
 627         struct autofs_sb_info *sbi;
 628         unsigned int cmd_first, cmd;
 629         ioctl_fn fn = NULL;
 630         int err = 0;
 631
 632         /* only root can play with this */
 633         if (!capable(CAP_SYS_ADMIN))
 634                 return -EPERM;
 635
 636         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 637         cmd = _IOC_NR(command);
 638
 639         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 640             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 641                 return -ENOTTY;
 642         }
 643
 644         /* Copy the parameters into kernel space. */
 645         param = copy_dev_ioctl(user);
 646         if (IS_ERR(param))
 647                 return PTR_ERR(param);
 648
 649         err = validate_dev_ioctl(command, param);
 650         if (err)
 651                 goto out;
 652
 653         /* The validate routine above always sets the version */
 654         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 655                 goto done;
 656
 657         fn = lookup_dev_ioctl(cmd);
 658         if (!fn) {
 659                 AUTOFS_WARN("unknown command 0x%08x", command);
 660                 return -ENOTTY;
 661         }
 662
 663         fp = NULL;
 664         sbi = NULL;
 665
 666         /*
 667          * For obvious reasons the openmount can't have a file
 668          * descriptor yet. We don't take a reference to the
 669          * file during close to allow for immediate release.
 670          */
 671         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 672             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 673                 fp = fget(param->ioctlfd);
 674                 if (!fp) {
 675                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 676                                 goto cont;
 677                         err = -EBADF;
 678                         goto out;
 679                 }
 680
 681                 if (!fp->f_op) {
 682                         err = -ENOTTY;
 683                         fput(fp);
 684                         goto out;
 685                 }
 686
 687                 sbi = autofs_dev_ioctl_sbi(fp);
 688                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 689                         err = -EINVAL;
 690                         fput(fp);
 691                         goto out;
 692                 }
 693
 694                 /*
 695                  * Admin needs to be able to set the mount catatonic in
 696                  * order to be able to perform the re-open.
 697                  */
 698                 if (!autofs4_oz_mode(sbi) &&
 699                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 700                         err = -EACCES;
 701                         fput(fp);
 702                         goto out;
 703                 }
 704         }
 705 cont:
 706         err = fn(fp, sbi, param);
 707
 708         if (fp)
 709                 fput(fp);
 710 done:
 711         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 712                 err = -EFAULT;
 713 out:
 714         free_dev_ioctl(param);
 715         return err;
 716 }
 717
 718 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 719 {
 720         int err;
 721         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 722         return (long) err;
 723 }
 724
 725 #ifdef CONFIG_COMPAT
 726 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 727 {
 728         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 729 }
 730 #else
 731 #define autofs_dev_ioctl_compat NULL
 732 #endif
 733
 734 static const struct file_operations _dev_ioctl_fops = {
 735         .unlocked_ioctl  = autofs_dev_ioctl,
 736         .compat_ioctl = autofs_dev_ioctl_compat,
 737         .owner   = THIS_MODULE,
 738 };
 739
 740 static struct miscdevice _autofs_dev_ioctl_misc = {
 741         .minor          = MISC_DYNAMIC_MINOR,
 742         .name           = AUTOFS_DEVICE_NAME,
 743         .fops           = &_dev_ioctl_fops
 744 };
 745
 746 /* Register/deregister misc character device */
 747 int autofs_dev_ioctl_init(void)
 748 {
 749         int r;
 750
 751         r = misc_register(&_autofs_dev_ioctl_misc);
 752         if (r) {
 753                 AUTOFS_ERROR("misc_register failed for control device");
 754                 return r;
 755         }
 756
 757         return 0;
 758 }
 759
 760 void autofs_dev_ioctl_exit(void)
 761 {
 762         misc_deregister(&_autofs_dev_ioctl_misc);
 763         return;
 764 }
 765