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         if (tmp.size > (PATH_MAX + sizeof(tmp)))
 107                 return ERR_PTR(-ENAMETOOLONG);
 108
 109         res = memdup_user(in, tmp.size);
 110         if (!IS_ERR(res))
 111                 res->size = tmp.size;
 112
 113         return res;
 114 }
 115
 116 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 117 {
 118         kfree(param);
 119         return;
 120 }
 121
 122 /*
 123  * Check sanity of parameter control fields and if a path is present
 124  * check that it is terminated and contains at least one "/".
 125  */
 126 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 127 {
 128         int err;
 129
 130         err = check_dev_ioctl_version(cmd, param);
 131         if (err) {
 132                 AUTOFS_WARN("invalid device control module version "
 133                      "supplied for cmd(0x%08x)", cmd);
 134                 goto out;
 135         }
 136
 137         if (param->size > sizeof(*param)) {
 138                 err = invalid_str(param->path, param->size - sizeof(*param));
 139                 if (err) {
 140                         AUTOFS_WARN(
 141                           "path string terminator missing for cmd(0x%08x)",
 142                           cmd);
 143                         goto out;
 144                 }
 145
 146                 err = check_name(param->path);
 147                 if (err) {
 148                         AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 149                                     cmd);
 150                         goto out;
 151                 }
 152         }
 153
 154         err = 0;
 155 out:
 156         return err;
 157 }
 158
 159 /*
 160  * Get the autofs super block info struct from the file opened on
 161  * the autofs mount point.
 162  */
 163 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 164 {
 165         struct autofs_sb_info *sbi = NULL;
 166         struct inode *inode;
 167
 168         if (f) {
 169                 inode = file_inode(f);
 170                 sbi = autofs4_sbi(inode->i_sb);
 171         }
 172         return sbi;
 173 }
 174
 175 /* Return autofs module protocol version */
 176 static int autofs_dev_ioctl_protover(struct file *fp,
 177                                      struct autofs_sb_info *sbi,
 178                                      struct autofs_dev_ioctl *param)
 179 {
 180         param->protover.version = sbi->version;
 181         return 0;
 182 }
 183
 184 /* Return autofs module protocol sub version */
 185 static int autofs_dev_ioctl_protosubver(struct file *fp,
 186                                         struct autofs_sb_info *sbi,
 187                                         struct autofs_dev_ioctl *param)
 188 {
 189         param->protosubver.sub_version = sbi->sub_version;
 190         return 0;
 191 }
 192
 193 /* Find the topmost mount satisfying test() */
 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_mountpoint(AT_FDCWD, pathname, &path, 0);
 201         if (err)
 202                 return err;
 203         err = -ENOENT;
 204         while (path.dentry == path.mnt->mnt_root) {
 205                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 206                         if (test(&path, data)) {
 207                                 path_get(&path);
 208                                 *res = path;
 209                                 err = 0;
 210                                 break;
 211                         }
 212                 }
 213                 if (!follow_up(&path))
 214                         break;
 215         }
 216         path_put(&path);
 217         return err;
 218 }
 219
 220 static int test_by_dev(struct path *path, void *p)
 221 {
 222         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 223 }
 224
 225 static int test_by_type(struct path *path, void *p)
 226 {
 227         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 228         return ino && ino->sbi->type & *(unsigned *)p;
 229 }
 230
 231 /*
 232  * Open a file descriptor on the autofs mount point corresponding
 233  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 234  */
 235 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 236 {
 237         int err, fd;
 238
 239         fd = get_unused_fd_flags(O_CLOEXEC);
 240         if (likely(fd >= 0)) {
 241                 struct file *filp;
 242                 struct path path;
 243
 244                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 245                 if (err)
 246                         goto out;
 247
 248                 /*
 249                  * Find autofs super block that has the device number
 250                  * corresponding to the autofs fs we want to open.
 251                  */
 252
 253                 filp = dentry_open(&path, O_RDONLY, current_cred());
 254                 path_put(&path);
 255                 if (IS_ERR(filp)) {
 256                         err = PTR_ERR(filp);
 257                         goto out;
 258                 }
 259
 260                 fd_install(fd, filp);
 261         }
 262
 263         return fd;
 264
 265 out:
 266         put_unused_fd(fd);
 267         return err;
 268 }
 269
 270 /* Open a file descriptor on an autofs mount point */
 271 static int autofs_dev_ioctl_openmount(struct file *fp,
 272                                       struct autofs_sb_info *sbi,
 273                                       struct autofs_dev_ioctl *param)
 274 {
 275         const char *path;
 276         dev_t devid;
 277         int err, fd;
 278
 279         /* param->path has already been checked */
 280         if (!param->openmount.devid)
 281                 return -EINVAL;
 282
 283         param->ioctlfd = -1;
 284
 285         path = param->path;
 286         devid = new_decode_dev(param->openmount.devid);
 287
 288         err = 0;
 289         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 290         if (unlikely(fd < 0)) {
 291                 err = fd;
 292                 goto out;
 293         }
 294
 295         param->ioctlfd = fd;
 296 out:
 297         return err;
 298 }
 299
 300 /* Close file descriptor allocated above (user can also use close(2)). */
 301 static int autofs_dev_ioctl_closemount(struct file *fp,
 302                                        struct autofs_sb_info *sbi,
 303                                        struct autofs_dev_ioctl *param)
 304 {
 305         return sys_close(param->ioctlfd);
 306 }
 307
 308 /*
 309  * Send "ready" status for an existing wait (either a mount or an expire
 310  * request).
 311  */
 312 static int autofs_dev_ioctl_ready(struct file *fp,
 313                                   struct autofs_sb_info *sbi,
 314                                   struct autofs_dev_ioctl *param)
 315 {
 316         autofs_wqt_t token;
 317
 318         token = (autofs_wqt_t) param->ready.token;
 319         return autofs4_wait_release(sbi, token, 0);
 320 }
 321
 322 /*
 323  * Send "fail" status for an existing wait (either a mount or an expire
 324  * request).
 325  */
 326 static int autofs_dev_ioctl_fail(struct file *fp,
 327                                  struct autofs_sb_info *sbi,
 328                                  struct autofs_dev_ioctl *param)
 329 {
 330         autofs_wqt_t token;
 331         int status;
 332
 333         token = (autofs_wqt_t) param->fail.token;
 334         status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 335         return autofs4_wait_release(sbi, token, status);
 336 }
 337
 338 /*
 339  * Set the pipe fd for kernel communication to the daemon.
 340  *
 341  * Normally this is set at mount using an option but if we
 342  * are reconnecting to a busy mount then we need to use this
 343  * to tell the autofs mount about the new kernel pipe fd. In
 344  * order to protect mounts against incorrectly setting the
 345  * pipefd we also require that the autofs mount be catatonic.
 346  *
 347  * This also sets the process group id used to identify the
 348  * controlling process (eg. the owning automount(8) daemon).
 349  */
 350 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 351                                       struct autofs_sb_info *sbi,
 352                                       struct autofs_dev_ioctl *param)
 353 {
 354         int pipefd;
 355         int err = 0;
 356         struct pid *new_pid = NULL;
 357
 358         if (param->setpipefd.pipefd == -1)
 359                 return -EINVAL;
 360
 361         pipefd = param->setpipefd.pipefd;
 362
 363         mutex_lock(&sbi->wq_mutex);
 364         if (!sbi->catatonic) {
 365                 mutex_unlock(&sbi->wq_mutex);
 366                 return -EBUSY;
 367         } else {
 368                 struct file *pipe;
 369
 370                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 371
 372                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 373                         AUTOFS_WARN("Not allowed to change PID namespace");
 374                         err = -EINVAL;
 375                         goto out;
 376                 }
 377
 378                 pipe = fget(pipefd);
 379                 if (!pipe) {
 380                         err = -EBADF;
 381                         goto out;
 382                 }
 383                 if (autofs_prepare_pipe(pipe) < 0) {
 384                         err = -EPIPE;
 385                         fput(pipe);
 386                         goto out;
 387                 }
 388                 swap(sbi->oz_pgrp, new_pid);
 389                 sbi->pipefd = pipefd;
 390                 sbi->pipe = pipe;
 391                 sbi->catatonic = 0;
 392         }
 393 out:
 394         put_pid(new_pid);
 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, 0);
 458                 spin_lock(&sbi->fs_lock);
 459                 param->requester.uid = from_kuid_munged(current_user_ns(), ino->uid);
 460                 param->requester.gid = from_kgid_munged(current_user_ns(), 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 path and check if it is the root of a mount.
 509  * If a type is given we are looking for a particular autofs
 510  * mount and if we don't find a match we return fail. If the
 511  * located path is the root of a mount we return 1 along with
 512  * the super magic 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_mountpoint(AT_FDCWD,
 541                                                    name, &path, LOOKUP_FOLLOW);
 542                 else
 543                         err = find_autofs_mount(name, &path,
 544                                                 test_by_type, &type);
 545                 if (err)
 546                         goto out;
 547                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 548                 err = 0;
 549                 if (path.mnt->mnt_root == path.dentry) {
 550                         err = 1;
 551                         magic = path.dentry->d_sb->s_magic;
 552                 }
 553         } else {
 554                 dev_t dev = sbi->sb->s_dev;
 555
 556                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 557                 if (err)
 558                         goto out;
 559
 560                 devid = new_encode_dev(dev);
 561
 562                 err = have_submounts(path.dentry);
 563
 564                 if (follow_down_one(&path))
 565                         magic = path.dentry->d_sb->s_magic;
 566         }
 567
 568         param->ismountpoint.out.devid = devid;
 569         param->ismountpoint.out.magic = magic;
 570         path_put(&path);
 571 out:
 572         return err;
 573 }
 574
 575 /*
 576  * Our range of ioctl numbers isn't 0 based so we need to shift
 577  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 578  * lookup.
 579  */
 580 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 581
 582 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 583 {
 584         static struct {
 585                 int cmd;
 586                 ioctl_fn fn;
 587         } _ioctls[] = {
 588                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 589                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 590                          autofs_dev_ioctl_protover},
 591                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 592                          autofs_dev_ioctl_protosubver},
 593                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 594                          autofs_dev_ioctl_openmount},
 595                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 596                          autofs_dev_ioctl_closemount},
 597                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 598                          autofs_dev_ioctl_ready},
 599                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 600                          autofs_dev_ioctl_fail},
 601                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 602                          autofs_dev_ioctl_setpipefd},
 603                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 604                          autofs_dev_ioctl_catatonic},
 605                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 606                          autofs_dev_ioctl_timeout},
 607                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 608                          autofs_dev_ioctl_requester},
 609                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 610                          autofs_dev_ioctl_expire},
 611                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 612                          autofs_dev_ioctl_askumount},
 613                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 614                          autofs_dev_ioctl_ismountpoint}
 615         };
 616         unsigned int idx = cmd_idx(cmd);
 617
 618         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 619 }
 620
 621 /* ioctl dispatcher */
 622 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 623 {
 624         struct autofs_dev_ioctl *param;
 625         struct file *fp;
 626         struct autofs_sb_info *sbi;
 627         unsigned int cmd_first, cmd;
 628         ioctl_fn fn = NULL;
 629         int err = 0;
 630
 631         /* only root can play with this */
 632         if (!capable(CAP_SYS_ADMIN))
 633                 return -EPERM;
 634
 635         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 636         cmd = _IOC_NR(command);
 637
 638         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 639             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 640                 return -ENOTTY;
 641         }
 642
 643         /* Copy the parameters into kernel space. */
 644         param = copy_dev_ioctl(user);
 645         if (IS_ERR(param))
 646                 return PTR_ERR(param);
 647
 648         err = validate_dev_ioctl(command, param);
 649         if (err)
 650                 goto out;
 651
 652         /* The validate routine above always sets the version */
 653         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 654                 goto done;
 655
 656         fn = lookup_dev_ioctl(cmd);
 657         if (!fn) {
 658                 AUTOFS_WARN("unknown command 0x%08x", command);
 659                 return -ENOTTY;
 660         }
 661
 662         fp = NULL;
 663         sbi = NULL;
 664
 665         /*
 666          * For obvious reasons the openmount can't have a file
 667          * descriptor yet. We don't take a reference to the
 668          * file during close to allow for immediate release.
 669          */
 670         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 671             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 672                 fp = fget(param->ioctlfd);
 673                 if (!fp) {
 674                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 675                                 goto cont;
 676                         err = -EBADF;
 677                         goto out;
 678                 }
 679
 680                 sbi = autofs_dev_ioctl_sbi(fp);
 681                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 682                         err = -EINVAL;
 683                         fput(fp);
 684                         goto out;
 685                 }
 686
 687                 /*
 688                  * Admin needs to be able to set the mount catatonic in
 689                  * order to be able to perform the re-open.
 690                  */
 691                 if (!autofs4_oz_mode(sbi) &&
 692                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 693                         err = -EACCES;
 694                         fput(fp);
 695                         goto out;
 696                 }
 697         }
 698 cont:
 699         err = fn(fp, sbi, param);
 700
 701         if (fp)
 702                 fput(fp);
 703 done:
 704         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 705                 err = -EFAULT;
 706 out:
 707         free_dev_ioctl(param);
 708         return err;
 709 }
 710
 711 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 712 {
 713         int err;
 714         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 715         return (long) err;
 716 }
 717
 718 #ifdef CONFIG_COMPAT
 719 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 720 {
 721         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 722 }
 723 #else
 724 #define autofs_dev_ioctl_compat NULL
 725 #endif
 726
 727 static const struct file_operations _dev_ioctl_fops = {
 728         .unlocked_ioctl  = autofs_dev_ioctl,
 729         .compat_ioctl = autofs_dev_ioctl_compat,
 730         .owner   = THIS_MODULE,
 731         .llseek = noop_llseek,
 732 };
 733
 734 static struct miscdevice _autofs_dev_ioctl_misc = {
 735         .minor          = AUTOFS_MINOR,
 736         .name           = AUTOFS_DEVICE_NAME,
 737         .fops           = &_dev_ioctl_fops
 738 };
 739
 740 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 741 MODULE_ALIAS("devname:autofs");
 742
 743 /* Register/deregister misc character device */
 744 int __init autofs_dev_ioctl_init(void)
 745 {
 746         int r;
 747
 748         r = misc_register(&_autofs_dev_ioctl_misc);
 749         if (r) {
 750                 AUTOFS_ERROR("misc_register failed for control device");
 751                 return r;
 752         }
 753
 754         return 0;
 755 }
 756
 757 void autofs_dev_ioctl_exit(void)
 758 {
 759         misc_deregister(&_autofs_dev_ioctl_misc);
 760         return;
 761 }
 762