fs/autofs/dev-ioctl.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright 2008 Red Hat, Inc. All rights reserved.
   4  * Copyright 2008 Ian Kent <raven@themaw.net>
   5  */
   6
   7 #include <linux/miscdevice.h>
   8 #include <linux/compat.h>
   9 #include <linux/syscalls.h>
  10 #include <linux/magic.h>
  11
  12 #include "autofs_i.h"
  13
  14 /*
  15  * This module implements an interface for routing autofs ioctl control
  16  * commands via a miscellaneous device file.
  17  *
  18  * The alternate interface is needed because we need to be able open
  19  * an ioctl file descriptor on an autofs mount that may be covered by
  20  * another mount. This situation arises when starting automount(8)
  21  * or other user space daemon which uses direct mounts or offset
  22  * mounts (used for autofs lazy mount/umount of nested mount trees),
  23  * which have been left busy at at service shutdown.
  24  */
  25
  26 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  27                         struct autofs_dev_ioctl *);
  28
  29 static int check_name(const char *name)
  30 {
  31         if (!strchr(name, '/'))
  32                 return -EINVAL;
  33         return 0;
  34 }
  35
  36 /*
  37  * Check a string doesn't overrun the chunk of
  38  * memory we copied from user land.
  39  */
  40 static int invalid_str(char *str, size_t size)
  41 {
  42         if (memchr(str, 0, size))
  43                 return 0;
  44         return -EINVAL;
  45 }
  46
  47 /*
  48  * Check that the user compiled against correct version of autofs
  49  * misc device code.
  50  *
  51  * As well as checking the version compatibility this always copies
  52  * the kernel interface version out.
  53  */
  54 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  55 {
  56         int err = 0;
  57
  58         if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
  59             (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
  60                 pr_warn("ioctl control interface version mismatch: "
  61                         "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
  62                         AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  63                         AUTOFS_DEV_IOCTL_VERSION_MINOR,
  64                         param->ver_major, param->ver_minor, cmd);
  65                 err = -EINVAL;
  66         }
  67
  68         /* Fill in the kernel version. */
  69         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  70         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  71
  72         return err;
  73 }
  74
  75 /*
  76  * Copy parameter control struct, including a possible path allocated
  77  * at the end of the struct.
  78  */
  79 static struct autofs_dev_ioctl *
  80 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  81 {
  82         struct autofs_dev_ioctl tmp, *res;
  83
  84         if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
  85                 return ERR_PTR(-EFAULT);
  86
  87         if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
  88                 return ERR_PTR(-EINVAL);
  89
  90         if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
  91                 return ERR_PTR(-ENAMETOOLONG);
  92
  93         res = memdup_user(in, tmp.size);
  94         if (!IS_ERR(res))
  95                 res->size = tmp.size;
  96
  97         return res;
  98 }
  99
 100 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 101 {
 102         kfree(param);
 103 }
 104
 105 /*
 106  * Check sanity of parameter control fields and if a path is present
 107  * check that it is terminated and contains at least one "/".
 108  */
 109 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 110 {
 111         int err;
 112
 113         err = check_dev_ioctl_version(cmd, param);
 114         if (err) {
 115                 pr_warn("invalid device control module version "
 116                         "supplied for cmd(0x%08x)\n", cmd);
 117                 goto out;
 118         }
 119
 120         if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
 121                 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
 122                 if (err) {
 123                         pr_warn(
 124                           "path string terminator missing for cmd(0x%08x)\n",
 125                           cmd);
 126                         goto out;
 127                 }
 128
 129                 err = check_name(param->path);
 130                 if (err) {
 131                         pr_warn("invalid path supplied for cmd(0x%08x)\n",
 132                                 cmd);
 133                         goto out;
 134                 }
 135         } else {
 136                 unsigned int inr = _IOC_NR(cmd);
 137
 138                 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
 139                     inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
 140                     inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
 141                         err = -EINVAL;
 142                         goto out;
 143                 }
 144         }
 145
 146         err = 0;
 147 out:
 148         return err;
 149 }
 150
 151 /* Return autofs dev ioctl version */
 152 static int autofs_dev_ioctl_version(struct file *fp,
 153                                     struct autofs_sb_info *sbi,
 154                                     struct autofs_dev_ioctl *param)
 155 {
 156         /* This should have already been set. */
 157         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
 158         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
 159         return 0;
 160 }
 161
 162 /* Return autofs module protocol version */
 163 static int autofs_dev_ioctl_protover(struct file *fp,
 164                                      struct autofs_sb_info *sbi,
 165                                      struct autofs_dev_ioctl *param)
 166 {
 167         param->protover.version = sbi->version;
 168         return 0;
 169 }
 170
 171 /* Return autofs module protocol sub version */
 172 static int autofs_dev_ioctl_protosubver(struct file *fp,
 173                                         struct autofs_sb_info *sbi,
 174                                         struct autofs_dev_ioctl *param)
 175 {
 176         param->protosubver.sub_version = sbi->sub_version;
 177         return 0;
 178 }
 179
 180 /* Find the topmost mount satisfying test() */
 181 static int find_autofs_mount(const char *pathname,
 182                              struct path *res,
 183                              int test(const struct path *path, void *data),
 184                              void *data)
 185 {
 186         struct path path;
 187         int err;
 188
 189         err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
 190         if (err)
 191                 return err;
 192         err = -ENOENT;
 193         while (path.dentry == path.mnt->mnt_root) {
 194                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 195                         if (test(&path, data)) {
 196                                 path_get(&path);
 197                                 *res = path;
 198                                 err = 0;
 199                                 break;
 200                         }
 201                 }
 202                 if (!follow_up(&path))
 203                         break;
 204         }
 205         path_put(&path);
 206         return err;
 207 }
 208
 209 static int test_by_dev(const struct path *path, void *p)
 210 {
 211         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 212 }
 213
 214 static int test_by_type(const struct path *path, void *p)
 215 {
 216         struct autofs_info *ino = autofs_dentry_ino(path->dentry);
 217
 218         return ino && ino->sbi->type & *(unsigned *)p;
 219 }
 220
 221 /*
 222  * Open a file descriptor on the autofs mount point corresponding
 223  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 224  */
 225 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 226 {
 227         int err, fd;
 228
 229         fd = get_unused_fd_flags(O_CLOEXEC);
 230         if (likely(fd >= 0)) {
 231                 struct file *filp;
 232                 struct path path;
 233
 234                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 235                 if (err)
 236                         goto out;
 237
 238                 filp = dentry_open(&path, O_RDONLY, current_cred());
 239                 path_put(&path);
 240                 if (IS_ERR(filp)) {
 241                         err = PTR_ERR(filp);
 242                         goto out;
 243                 }
 244
 245                 fd_install(fd, filp);
 246         }
 247
 248         return fd;
 249
 250 out:
 251         put_unused_fd(fd);
 252         return err;
 253 }
 254
 255 /* Open a file descriptor on an autofs mount point */
 256 static int autofs_dev_ioctl_openmount(struct file *fp,
 257                                       struct autofs_sb_info *sbi,
 258                                       struct autofs_dev_ioctl *param)
 259 {
 260         const char *path;
 261         dev_t devid;
 262         int err, fd;
 263
 264         /* param->path has been checked in validate_dev_ioctl() */
 265
 266         if (!param->openmount.devid)
 267                 return -EINVAL;
 268
 269         param->ioctlfd = -1;
 270
 271         path = param->path;
 272         devid = new_decode_dev(param->openmount.devid);
 273
 274         err = 0;
 275         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 276         if (unlikely(fd < 0)) {
 277                 err = fd;
 278                 goto out;
 279         }
 280
 281         param->ioctlfd = fd;
 282 out:
 283         return err;
 284 }
 285
 286 /* Close file descriptor allocated above (user can also use close(2)). */
 287 static int autofs_dev_ioctl_closemount(struct file *fp,
 288                                        struct autofs_sb_info *sbi,
 289                                        struct autofs_dev_ioctl *param)
 290 {
 291         return ksys_close(param->ioctlfd);
 292 }
 293
 294 /*
 295  * Send "ready" status for an existing wait (either a mount or an expire
 296  * request).
 297  */
 298 static int autofs_dev_ioctl_ready(struct file *fp,
 299                                   struct autofs_sb_info *sbi,
 300                                   struct autofs_dev_ioctl *param)
 301 {
 302         autofs_wqt_t token;
 303
 304         token = (autofs_wqt_t) param->ready.token;
 305         return autofs_wait_release(sbi, token, 0);
 306 }
 307
 308 /*
 309  * Send "fail" status for an existing wait (either a mount or an expire
 310  * request).
 311  */
 312 static int autofs_dev_ioctl_fail(struct file *fp,
 313                                  struct autofs_sb_info *sbi,
 314                                  struct autofs_dev_ioctl *param)
 315 {
 316         autofs_wqt_t token;
 317         int status;
 318
 319         token = (autofs_wqt_t) param->fail.token;
 320         status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 321         return autofs_wait_release(sbi, token, status);
 322 }
 323
 324 /*
 325  * Set the pipe fd for kernel communication to the daemon.
 326  *
 327  * Normally this is set at mount using an option but if we
 328  * are reconnecting to a busy mount then we need to use this
 329  * to tell the autofs mount about the new kernel pipe fd. In
 330  * order to protect mounts against incorrectly setting the
 331  * pipefd we also require that the autofs mount be catatonic.
 332  *
 333  * This also sets the process group id used to identify the
 334  * controlling process (eg. the owning automount(8) daemon).
 335  */
 336 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 337                                       struct autofs_sb_info *sbi,
 338                                       struct autofs_dev_ioctl *param)
 339 {
 340         int pipefd;
 341         int err = 0;
 342         struct pid *new_pid = NULL;
 343
 344         if (param->setpipefd.pipefd == -1)
 345                 return -EINVAL;
 346
 347         pipefd = param->setpipefd.pipefd;
 348
 349         mutex_lock(&sbi->wq_mutex);
 350         if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
 351                 mutex_unlock(&sbi->wq_mutex);
 352                 return -EBUSY;
 353         } else {
 354                 struct file *pipe;
 355
 356                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 357
 358                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 359                         pr_warn("not allowed to change PID namespace\n");
 360                         err = -EINVAL;
 361                         goto out;
 362                 }
 363
 364                 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                 swap(sbi->oz_pgrp, new_pid);
 375                 sbi->pipefd = pipefd;
 376                 sbi->pipe = pipe;
 377                 sbi->flags &= ~AUTOFS_SBI_CATATONIC;
 378         }
 379 out:
 380         put_pid(new_pid);
 381         mutex_unlock(&sbi->wq_mutex);
 382         return err;
 383 }
 384
 385 /*
 386  * Make the autofs mount point catatonic, no longer responsive to
 387  * mount requests. Also closes the kernel pipe file descriptor.
 388  */
 389 static int autofs_dev_ioctl_catatonic(struct file *fp,
 390                                       struct autofs_sb_info *sbi,
 391                                       struct autofs_dev_ioctl *param)
 392 {
 393         autofs_catatonic_mode(sbi);
 394         return 0;
 395 }
 396
 397 /* Set the autofs mount timeout */
 398 static int autofs_dev_ioctl_timeout(struct file *fp,
 399                                     struct autofs_sb_info *sbi,
 400                                     struct autofs_dev_ioctl *param)
 401 {
 402         unsigned long timeout;
 403
 404         timeout = param->timeout.timeout;
 405         param->timeout.timeout = sbi->exp_timeout / HZ;
 406         sbi->exp_timeout = timeout * HZ;
 407         return 0;
 408 }
 409
 410 /*
 411  * Return the uid and gid of the last request for the mount
 412  *
 413  * When reconstructing an autofs mount tree with active mounts
 414  * we need to re-connect to mounts that may have used the original
 415  * process uid and gid (or string variations of them) for mount
 416  * lookups within the map entry.
 417  */
 418 static int autofs_dev_ioctl_requester(struct file *fp,
 419                                       struct autofs_sb_info *sbi,
 420                                       struct autofs_dev_ioctl *param)
 421 {
 422         struct autofs_info *ino;
 423         struct path path;
 424         dev_t devid;
 425         int err = -ENOENT;
 426
 427         /* param->path has been checked in validate_dev_ioctl() */
 428
 429         devid = sbi->sb->s_dev;
 430
 431         param->requester.uid = param->requester.gid = -1;
 432
 433         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 434         if (err)
 435                 goto out;
 436
 437         ino = autofs_dentry_ino(path.dentry);
 438         if (ino) {
 439                 err = 0;
 440                 autofs_expire_wait(&path, 0);
 441                 spin_lock(&sbi->fs_lock);
 442                 param->requester.uid =
 443                         from_kuid_munged(current_user_ns(), ino->uid);
 444                 param->requester.gid =
 445                         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 autofs_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         /* param->path has been checked in validate_dev_ioctl() */
 513
 514         name = param->path;
 515         type = param->ismountpoint.in.type;
 516
 517         param->ismountpoint.out.devid = devid = 0;
 518         param->ismountpoint.out.magic = magic = 0;
 519
 520         if (!fp || param->ioctlfd == -1) {
 521                 if (autofs_type_any(type))
 522                         err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
 523                                         &path);
 524                 else
 525                         err = find_autofs_mount(name, &path,
 526                                                 test_by_type, &type);
 527                 if (err)
 528                         goto out;
 529                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 530                 err = 0;
 531                 if (path.mnt->mnt_root == path.dentry) {
 532                         err = 1;
 533                         magic = path.dentry->d_sb->s_magic;
 534                 }
 535         } else {
 536                 dev_t dev = sbi->sb->s_dev;
 537
 538                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 539                 if (err)
 540                         goto out;
 541
 542                 devid = new_encode_dev(dev);
 543
 544                 err = path_has_submounts(&path);
 545
 546                 if (follow_down_one(&path))
 547                         magic = path.dentry->d_sb->s_magic;
 548         }
 549
 550         param->ismountpoint.out.devid = devid;
 551         param->ismountpoint.out.magic = magic;
 552         path_put(&path);
 553 out:
 554         return err;
 555 }
 556
 557 /*
 558  * Our range of ioctl numbers isn't 0 based so we need to shift
 559  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 560  * lookup.
 561  */
 562 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 563
 564 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 565 {
 566         static ioctl_fn _ioctls[] = {
 567                 autofs_dev_ioctl_version,
 568                 autofs_dev_ioctl_protover,
 569                 autofs_dev_ioctl_protosubver,
 570                 autofs_dev_ioctl_openmount,
 571                 autofs_dev_ioctl_closemount,
 572                 autofs_dev_ioctl_ready,
 573                 autofs_dev_ioctl_fail,
 574                 autofs_dev_ioctl_setpipefd,
 575                 autofs_dev_ioctl_catatonic,
 576                 autofs_dev_ioctl_timeout,
 577                 autofs_dev_ioctl_requester,
 578                 autofs_dev_ioctl_expire,
 579                 autofs_dev_ioctl_askumount,
 580                 autofs_dev_ioctl_ismountpoint,
 581         };
 582         unsigned int idx = cmd_idx(cmd);
 583
 584         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
 585 }
 586
 587 /* ioctl dispatcher */
 588 static int _autofs_dev_ioctl(unsigned int command,
 589                              struct autofs_dev_ioctl __user *user)
 590 {
 591         struct autofs_dev_ioctl *param;
 592         struct file *fp;
 593         struct autofs_sb_info *sbi;
 594         unsigned int cmd_first, cmd;
 595         ioctl_fn fn = NULL;
 596         int err = 0;
 597
 598         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 599         cmd = _IOC_NR(command);
 600
 601         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 602             cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
 603                 return -ENOTTY;
 604         }
 605
 606         /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
 607          * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
 608          */
 609         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 610             cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
 611             !capable(CAP_SYS_ADMIN))
 612                 return -EPERM;
 613
 614         /* Copy the parameters into kernel space. */
 615         param = copy_dev_ioctl(user);
 616         if (IS_ERR(param))
 617                 return PTR_ERR(param);
 618
 619         err = validate_dev_ioctl(command, param);
 620         if (err)
 621                 goto out;
 622
 623         fn = lookup_dev_ioctl(cmd);
 624         if (!fn) {
 625                 pr_warn("unknown command 0x%08x\n", command);
 626                 err = -ENOTTY;
 627                 goto out;
 628         }
 629
 630         fp = NULL;
 631         sbi = NULL;
 632
 633         /*
 634          * For obvious reasons the openmount can't have a file
 635          * descriptor yet. We don't take a reference to the
 636          * file during close to allow for immediate release,
 637          * and the same for retrieving ioctl version.
 638          */
 639         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 640             cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 641             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 642                 struct super_block *sb;
 643
 644                 fp = fget(param->ioctlfd);
 645                 if (!fp) {
 646                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 647                                 goto cont;
 648                         err = -EBADF;
 649                         goto out;
 650                 }
 651
 652                 sb = file_inode(fp)->i_sb;
 653                 if (sb->s_type != &autofs_fs_type) {
 654                         err = -EINVAL;
 655                         fput(fp);
 656                         goto out;
 657                 }
 658                 sbi = autofs_sbi(sb);
 659
 660                 /*
 661                  * Admin needs to be able to set the mount catatonic in
 662                  * order to be able to perform the re-open.
 663                  */
 664                 if (!autofs_oz_mode(sbi) &&
 665                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 666                         err = -EACCES;
 667                         fput(fp);
 668                         goto out;
 669                 }
 670         }
 671 cont:
 672         err = fn(fp, sbi, param);
 673
 674         if (fp)
 675                 fput(fp);
 676         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 677                 err = -EFAULT;
 678 out:
 679         free_dev_ioctl(param);
 680         return err;
 681 }
 682
 683 static long autofs_dev_ioctl(struct file *file, unsigned int command,
 684                              unsigned long u)
 685 {
 686         int err;
 687
 688         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 689         return (long) err;
 690 }
 691
 692 #ifdef CONFIG_COMPAT
 693 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
 694                                     unsigned long u)
 695 {
 696         return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
 697 }
 698 #else
 699 #define autofs_dev_ioctl_compat NULL
 700 #endif
 701
 702 static const struct file_operations _dev_ioctl_fops = {
 703         .unlocked_ioctl  = autofs_dev_ioctl,
 704         .compat_ioctl = autofs_dev_ioctl_compat,
 705         .owner   = THIS_MODULE,
 706         .llseek = noop_llseek,
 707 };
 708
 709 static struct miscdevice _autofs_dev_ioctl_misc = {
 710         .minor          = AUTOFS_MINOR,
 711         .name           = AUTOFS_DEVICE_NAME,
 712         .fops           = &_dev_ioctl_fops,
 713         .mode           = 0644,
 714 };
 715
 716 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 717 MODULE_ALIAS("devname:autofs");
 718
 719 /* Register/deregister misc character device */
 720 int __init autofs_dev_ioctl_init(void)
 721 {
 722         int r;
 723
 724         r = misc_register(&_autofs_dev_ioctl_misc);
 725         if (r) {
 726                 pr_err("misc_register failed for control device\n");
 727                 return r;
 728         }
 729
 730         return 0;
 731 }
 732
 733 void autofs_dev_ioctl_exit(void)
 734 {
 735         misc_deregister(&_autofs_dev_ioctl_misc);
 736 }