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