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 #include <linux/nospec.h>
  12
  13 #include "autofs_i.h"
  14
  15 /*
  16  * This module implements an interface for routing autofs ioctl control
  17  * commands via a miscellaneous device file.
  18  *
  19  * The alternate interface is needed because we need to be able open
  20  * an ioctl file descriptor on an autofs mount that may be covered by
  21  * another mount. This situation arises when starting automount(8)
  22  * or other user space daemon which uses direct mounts or offset
  23  * mounts (used for autofs lazy mount/umount of nested mount trees),
  24  * which have been left busy at service shutdown.
  25  */
  26
  27 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  28                         struct autofs_dev_ioctl *);
  29
  30 static int check_name(const char *name)
  31 {
  32         if (!strchr(name, '/'))
  33                 return -EINVAL;
  34         return 0;
  35 }
  36
  37 /*
  38  * Check a string doesn't overrun the chunk of
  39  * memory we copied from user land.
  40  */
  41 static int invalid_str(char *str, size_t size)
  42 {
  43         if (memchr(str, 0, size))
  44                 return 0;
  45         return -EINVAL;
  46 }
  47
  48 /*
  49  * Check that the user compiled against correct version of autofs
  50  * misc device code.
  51  *
  52  * As well as checking the version compatibility this always copies
  53  * the kernel interface version out.
  54  */
  55 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  56 {
  57         int err = 0;
  58
  59         if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
  60             (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
  61                 pr_warn("ioctl control interface version mismatch: "
  62                         "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
  63                         AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  64                         AUTOFS_DEV_IOCTL_VERSION_MINOR,
  65                         param->ver_major, param->ver_minor, cmd);
  66                 err = -EINVAL;
  67         }
  68
  69         /* Fill in the kernel version. */
  70         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  71         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  72
  73         return err;
  74 }
  75
  76 /*
  77  * Copy parameter control struct, including a possible path allocated
  78  * at the end of the struct.
  79  */
  80 static struct autofs_dev_ioctl *
  81 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  82 {
  83         struct autofs_dev_ioctl tmp, *res;
  84
  85         if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
  86                 return ERR_PTR(-EFAULT);
  87
  88         if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
  89                 return ERR_PTR(-EINVAL);
  90
  91         if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
  92                 return ERR_PTR(-ENAMETOOLONG);
  93
  94         res = memdup_user(in, tmp.size);
  95         if (!IS_ERR(res))
  96                 res->size = tmp.size;
  97
  98         return res;
  99 }
 100
 101 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 102 {
 103         kfree(param);
 104 }
 105
 106 /*
 107  * Check sanity of parameter control fields and if a path is present
 108  * check that it is terminated and contains at least one "/".
 109  */
 110 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 111 {
 112         int err;
 113
 114         err = check_dev_ioctl_version(cmd, param);
 115         if (err) {
 116                 pr_warn("invalid device control module version "
 117                         "supplied for cmd(0x%08x)\n", cmd);
 118                 goto out;
 119         }
 120
 121         if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
 122                 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
 123                 if (err) {
 124                         pr_warn(
 125                           "path string terminator missing for cmd(0x%08x)\n",
 126                           cmd);
 127                         goto out;
 128                 }
 129
 130                 err = check_name(param->path);
 131                 if (err) {
 132                         pr_warn("invalid path supplied for cmd(0x%08x)\n",
 133                                 cmd);
 134                         goto out;
 135                 }
 136         } else {
 137                 unsigned int inr = _IOC_NR(cmd);
 138
 139                 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
 140                     inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
 141                     inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
 142                         err = -EINVAL;
 143                         goto out;
 144                 }
 145         }
 146
 147         err = 0;
 148 out:
 149         return err;
 150 }
 151
 152 /* Return autofs dev ioctl version */
 153 static int autofs_dev_ioctl_version(struct file *fp,
 154                                     struct autofs_sb_info *sbi,
 155                                     struct autofs_dev_ioctl *param)
 156 {
 157         /* This should have already been set. */
 158         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
 159         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
 160         return 0;
 161 }
 162
 163 /* Return autofs module protocol version */
 164 static int autofs_dev_ioctl_protover(struct file *fp,
 165                                      struct autofs_sb_info *sbi,
 166                                      struct autofs_dev_ioctl *param)
 167 {
 168         param->protover.version = sbi->version;
 169         return 0;
 170 }
 171
 172 /* Return autofs module protocol sub version */
 173 static int autofs_dev_ioctl_protosubver(struct file *fp,
 174                                         struct autofs_sb_info *sbi,
 175                                         struct autofs_dev_ioctl *param)
 176 {
 177         param->protosubver.sub_version = sbi->sub_version;
 178         return 0;
 179 }
 180
 181 /* Find the topmost mount satisfying test() */
 182 static int find_autofs_mount(const char *pathname,
 183                              struct path *res,
 184                              int test(const struct path *path, void *data),
 185                              void *data)
 186 {
 187         struct path path;
 188         int err;
 189
 190         err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
 191         if (err)
 192                 return err;
 193         err = -ENOENT;
 194         while (path.dentry == path.mnt->mnt_root) {
 195                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 196                         if (test(&path, data)) {
 197                                 path_get(&path);
 198                                 *res = path;
 199                                 err = 0;
 200                                 break;
 201                         }
 202                 }
 203                 if (!follow_up(&path))
 204                         break;
 205         }
 206         path_put(&path);
 207         return err;
 208 }
 209
 210 static int test_by_dev(const struct path *path, void *p)
 211 {
 212         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 213 }
 214
 215 static int test_by_type(const struct path *path, void *p)
 216 {
 217         struct autofs_info *ino = autofs_dentry_ino(path->dentry);
 218
 219         return ino && ino->sbi->type & *(unsigned *)p;
 220 }
 221
 222 /*
 223  * Open a file descriptor on the autofs mount point corresponding
 224  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 225  */
 226 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 227 {
 228         int err, fd;
 229
 230         fd = get_unused_fd_flags(O_CLOEXEC);
 231         if (likely(fd >= 0)) {
 232                 struct file *filp;
 233                 struct path path;
 234
 235                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 236                 if (err)
 237                         goto out;
 238
 239                 filp = dentry_open(&path, O_RDONLY, current_cred());
 240                 path_put(&path);
 241                 if (IS_ERR(filp)) {
 242                         err = PTR_ERR(filp);
 243                         goto out;
 244                 }
 245
 246                 fd_install(fd, filp);
 247         }
 248
 249         return fd;
 250
 251 out:
 252         put_unused_fd(fd);
 253         return err;
 254 }
 255
 256 /* Open a file descriptor on an autofs mount point */
 257 static int autofs_dev_ioctl_openmount(struct file *fp,
 258                                       struct autofs_sb_info *sbi,
 259                                       struct autofs_dev_ioctl *param)
 260 {
 261         const char *path;
 262         dev_t devid;
 263         int err, fd;
 264
 265         /* param->path has been checked in validate_dev_ioctl() */
 266
 267         if (!param->openmount.devid)
 268                 return -EINVAL;
 269
 270         param->ioctlfd = -1;
 271
 272         path = param->path;
 273         devid = new_decode_dev(param->openmount.devid);
 274
 275         err = 0;
 276         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 277         if (unlikely(fd < 0)) {
 278                 err = fd;
 279                 goto out;
 280         }
 281
 282         param->ioctlfd = fd;
 283 out:
 284         return err;
 285 }
 286
 287 /* Close file descriptor allocated above (user can also use close(2)). */
 288 static int autofs_dev_ioctl_closemount(struct file *fp,
 289                                        struct autofs_sb_info *sbi,
 290                                        struct autofs_dev_ioctl *param)
 291 {
 292         return ksys_close(param->ioctlfd);
 293 }
 294
 295 /*
 296  * Send "ready" status for an existing wait (either a mount or an expire
 297  * request).
 298  */
 299 static int autofs_dev_ioctl_ready(struct file *fp,
 300                                   struct autofs_sb_info *sbi,
 301                                   struct autofs_dev_ioctl *param)
 302 {
 303         autofs_wqt_t token;
 304
 305         token = (autofs_wqt_t) param->ready.token;
 306         return autofs_wait_release(sbi, token, 0);
 307 }
 308
 309 /*
 310  * Send "fail" status for an existing wait (either a mount or an expire
 311  * request).
 312  */
 313 static int autofs_dev_ioctl_fail(struct file *fp,
 314                                  struct autofs_sb_info *sbi,
 315                                  struct autofs_dev_ioctl *param)
 316 {
 317         autofs_wqt_t token;
 318         int status;
 319
 320         token = (autofs_wqt_t) param->fail.token;
 321         status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 322         return autofs_wait_release(sbi, token, status);
 323 }
 324
 325 /*
 326  * Set the pipe fd for kernel communication to the daemon.
 327  *
 328  * Normally this is set at mount using an option but if we
 329  * are reconnecting to a busy mount then we need to use this
 330  * to tell the autofs mount about the new kernel pipe fd. In
 331  * order to protect mounts against incorrectly setting the
 332  * pipefd we also require that the autofs mount be catatonic.
 333  *
 334  * This also sets the process group id used to identify the
 335  * controlling process (eg. the owning automount(8) daemon).
 336  */
 337 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 338                                       struct autofs_sb_info *sbi,
 339                                       struct autofs_dev_ioctl *param)
 340 {
 341         int pipefd;
 342         int err = 0;
 343         struct pid *new_pid = NULL;
 344
 345         if (param->setpipefd.pipefd == -1)
 346                 return -EINVAL;
 347
 348         pipefd = param->setpipefd.pipefd;
 349
 350         mutex_lock(&sbi->wq_mutex);
 351         if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
 352                 mutex_unlock(&sbi->wq_mutex);
 353                 return -EBUSY;
 354         } else {
 355                 struct file *pipe;
 356
 357                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 358
 359                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 360                         pr_warn("not allowed to change PID namespace\n");
 361                         err = -EINVAL;
 362                         goto out;
 363                 }
 364
 365                 pipe = fget(pipefd);
 366                 if (!pipe) {
 367                         err = -EBADF;
 368                         goto out;
 369                 }
 370                 if (autofs_prepare_pipe(pipe) < 0) {
 371                         err = -EPIPE;
 372                         fput(pipe);
 373                         goto out;
 374                 }
 375                 swap(sbi->oz_pgrp, new_pid);
 376                 sbi->pipefd = pipefd;
 377                 sbi->pipe = pipe;
 378                 sbi->flags &= ~AUTOFS_SBI_CATATONIC;
 379         }
 380 out:
 381         put_pid(new_pid);
 382         mutex_unlock(&sbi->wq_mutex);
 383         return err;
 384 }
 385
 386 /*
 387  * Make the autofs mount point catatonic, no longer responsive to
 388  * mount requests. Also closes the kernel pipe file descriptor.
 389  */
 390 static int autofs_dev_ioctl_catatonic(struct file *fp,
 391                                       struct autofs_sb_info *sbi,
 392                                       struct autofs_dev_ioctl *param)
 393 {
 394         autofs_catatonic_mode(sbi);
 395         return 0;
 396 }
 397
 398 /* Set the autofs mount timeout */
 399 static int autofs_dev_ioctl_timeout(struct file *fp,
 400                                     struct autofs_sb_info *sbi,
 401                                     struct autofs_dev_ioctl *param)
 402 {
 403         unsigned long timeout;
 404
 405         timeout = param->timeout.timeout;
 406         param->timeout.timeout = sbi->exp_timeout / HZ;
 407         sbi->exp_timeout = timeout * HZ;
 408         return 0;
 409 }
 410
 411 /*
 412  * Return the uid and gid of the last request for the mount
 413  *
 414  * When reconstructing an autofs mount tree with active mounts
 415  * we need to re-connect to mounts that may have used the original
 416  * process uid and gid (or string variations of them) for mount
 417  * lookups within the map entry.
 418  */
 419 static int autofs_dev_ioctl_requester(struct file *fp,
 420                                       struct autofs_sb_info *sbi,
 421                                       struct autofs_dev_ioctl *param)
 422 {
 423         struct autofs_info *ino;
 424         struct path path;
 425         dev_t devid;
 426         int err = -ENOENT;
 427
 428         /* param->path has been checked in validate_dev_ioctl() */
 429
 430         devid = sbi->sb->s_dev;
 431
 432         param->requester.uid = param->requester.gid = -1;
 433
 434         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 435         if (err)
 436                 goto out;
 437
 438         ino = autofs_dentry_ino(path.dentry);
 439         if (ino) {
 440                 err = 0;
 441                 autofs_expire_wait(&path, 0);
 442                 spin_lock(&sbi->fs_lock);
 443                 param->requester.uid =
 444                         from_kuid_munged(current_user_ns(), ino->uid);
 445                 param->requester.gid =
 446                         from_kgid_munged(current_user_ns(), ino->gid);
 447                 spin_unlock(&sbi->fs_lock);
 448         }
 449         path_put(&path);
 450 out:
 451         return err;
 452 }
 453
 454 /*
 455  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 456  * more that can be done.
 457  */
 458 static int autofs_dev_ioctl_expire(struct file *fp,
 459                                    struct autofs_sb_info *sbi,
 460                                    struct autofs_dev_ioctl *param)
 461 {
 462         struct vfsmount *mnt;
 463         int how;
 464
 465         how = param->expire.how;
 466         mnt = fp->f_path.mnt;
 467
 468         return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
 469 }
 470
 471 /* Check if autofs mount point is in use */
 472 static int autofs_dev_ioctl_askumount(struct file *fp,
 473                                       struct autofs_sb_info *sbi,
 474                                       struct autofs_dev_ioctl *param)
 475 {
 476         param->askumount.may_umount = 0;
 477         if (may_umount(fp->f_path.mnt))
 478                 param->askumount.may_umount = 1;
 479         return 0;
 480 }
 481
 482 /*
 483  * Check if the given path is a mountpoint.
 484  *
 485  * If we are supplied with the file descriptor of an autofs
 486  * mount we're looking for a specific mount. In this case
 487  * the path is considered a mountpoint if it is itself a
 488  * mountpoint or contains a mount, such as a multi-mount
 489  * without a root mount. In this case we return 1 if the
 490  * path is a mount point and the super magic of the covering
 491  * mount if there is one or 0 if it isn't a mountpoint.
 492  *
 493  * If we aren't supplied with a file descriptor then we
 494  * lookup the path and check if it is the root of a mount.
 495  * If a type is given we are looking for a particular autofs
 496  * mount and if we don't find a match we return fail. If the
 497  * located path is the root of a mount we return 1 along with
 498  * the super magic of the mount or 0 otherwise.
 499  *
 500  * In both cases the device number (as returned by
 501  * new_encode_dev()) is also returned.
 502  */
 503 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 504                                          struct autofs_sb_info *sbi,
 505                                          struct autofs_dev_ioctl *param)
 506 {
 507         struct path path;
 508         const char *name;
 509         unsigned int type;
 510         unsigned int devid, magic;
 511         int err = -ENOENT;
 512
 513         /* param->path has been checked in validate_dev_ioctl() */
 514
 515         name = param->path;
 516         type = param->ismountpoint.in.type;
 517
 518         param->ismountpoint.out.devid = devid = 0;
 519         param->ismountpoint.out.magic = magic = 0;
 520
 521         if (!fp || param->ioctlfd == -1) {
 522                 if (autofs_type_any(type))
 523                         err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
 524                                         &path);
 525                 else
 526                         err = find_autofs_mount(name, &path,
 527                                                 test_by_type, &type);
 528                 if (err)
 529                         goto out;
 530                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 531                 err = 0;
 532                 if (path.mnt->mnt_root == path.dentry) {
 533                         err = 1;
 534                         magic = path.dentry->d_sb->s_magic;
 535                 }
 536         } else {
 537                 dev_t dev = sbi->sb->s_dev;
 538
 539                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 540                 if (err)
 541                         goto out;
 542
 543                 devid = new_encode_dev(dev);
 544
 545                 err = path_has_submounts(&path);
 546
 547                 if (follow_down_one(&path))
 548                         magic = path.dentry->d_sb->s_magic;
 549         }
 550
 551         param->ismountpoint.out.devid = devid;
 552         param->ismountpoint.out.magic = magic;
 553         path_put(&path);
 554 out:
 555         return err;
 556 }
 557
 558 /*
 559  * Our range of ioctl numbers isn't 0 based so we need to shift
 560  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 561  * lookup.
 562  */
 563 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 564
 565 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 566 {
 567         static const ioctl_fn _ioctls[] = {
 568                 autofs_dev_ioctl_version,
 569                 autofs_dev_ioctl_protover,
 570                 autofs_dev_ioctl_protosubver,
 571                 autofs_dev_ioctl_openmount,
 572                 autofs_dev_ioctl_closemount,
 573                 autofs_dev_ioctl_ready,
 574                 autofs_dev_ioctl_fail,
 575                 autofs_dev_ioctl_setpipefd,
 576                 autofs_dev_ioctl_catatonic,
 577                 autofs_dev_ioctl_timeout,
 578                 autofs_dev_ioctl_requester,
 579                 autofs_dev_ioctl_expire,
 580                 autofs_dev_ioctl_askumount,
 581                 autofs_dev_ioctl_ismountpoint,
 582         };
 583         unsigned int idx = cmd_idx(cmd);
 584
 585         if (idx >= ARRAY_SIZE(_ioctls))
 586                 return NULL;
 587         idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls));
 588         return _ioctls[idx];
 589 }
 590
 591 /* ioctl dispatcher */
 592 static int _autofs_dev_ioctl(unsigned int command,
 593                              struct autofs_dev_ioctl __user *user)
 594 {
 595         struct autofs_dev_ioctl *param;
 596         struct file *fp;
 597         struct autofs_sb_info *sbi;
 598         unsigned int cmd_first, cmd;
 599         ioctl_fn fn = NULL;
 600         int err = 0;
 601
 602         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 603         cmd = _IOC_NR(command);
 604
 605         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 606             cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
 607                 return -ENOTTY;
 608         }
 609
 610         /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
 611          * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
 612          */
 613         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 614             cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
 615             !capable(CAP_SYS_ADMIN))
 616                 return -EPERM;
 617
 618         /* Copy the parameters into kernel space. */
 619         param = copy_dev_ioctl(user);
 620         if (IS_ERR(param))
 621                 return PTR_ERR(param);
 622
 623         err = validate_dev_ioctl(command, param);
 624         if (err)
 625                 goto out;
 626
 627         fn = lookup_dev_ioctl(cmd);
 628         if (!fn) {
 629                 pr_warn("unknown command 0x%08x\n", command);
 630                 err = -ENOTTY;
 631                 goto out;
 632         }
 633
 634         fp = NULL;
 635         sbi = NULL;
 636
 637         /*
 638          * For obvious reasons the openmount can't have a file
 639          * descriptor yet. We don't take a reference to the
 640          * file during close to allow for immediate release,
 641          * and the same for retrieving ioctl version.
 642          */
 643         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 644             cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 645             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 646                 struct super_block *sb;
 647
 648                 fp = fget(param->ioctlfd);
 649                 if (!fp) {
 650                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 651                                 goto cont;
 652                         err = -EBADF;
 653                         goto out;
 654                 }
 655
 656                 sb = file_inode(fp)->i_sb;
 657                 if (sb->s_type != &autofs_fs_type) {
 658                         err = -EINVAL;
 659                         fput(fp);
 660                         goto out;
 661                 }
 662                 sbi = autofs_sbi(sb);
 663
 664                 /*
 665                  * Admin needs to be able to set the mount catatonic in
 666                  * order to be able to perform the re-open.
 667                  */
 668                 if (!autofs_oz_mode(sbi) &&
 669                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 670                         err = -EACCES;
 671                         fput(fp);
 672                         goto out;
 673                 }
 674         }
 675 cont:
 676         err = fn(fp, sbi, param);
 677
 678         if (fp)
 679                 fput(fp);
 680         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 681                 err = -EFAULT;
 682 out:
 683         free_dev_ioctl(param);
 684         return err;
 685 }
 686
 687 static long autofs_dev_ioctl(struct file *file, unsigned int command,
 688                              unsigned long u)
 689 {
 690         int err;
 691
 692         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 693         return (long) err;
 694 }
 695
 696 #ifdef CONFIG_COMPAT
 697 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
 698                                     unsigned long u)
 699 {
 700         return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
 701 }
 702 #else
 703 #define autofs_dev_ioctl_compat NULL
 704 #endif
 705
 706 static const struct file_operations _dev_ioctl_fops = {
 707         .unlocked_ioctl  = autofs_dev_ioctl,
 708         .compat_ioctl = autofs_dev_ioctl_compat,
 709         .owner   = THIS_MODULE,
 710         .llseek = noop_llseek,
 711 };
 712
 713 static struct miscdevice _autofs_dev_ioctl_misc = {
 714         .minor          = AUTOFS_MINOR,
 715         .name           = AUTOFS_DEVICE_NAME,
 716         .fops           = &_dev_ioctl_fops,
 717         .mode           = 0644,
 718 };
 719
 720 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 721 MODULE_ALIAS("devname:autofs");
 722
 723 /* Register/deregister misc character device */
 724 int __init autofs_dev_ioctl_init(void)
 725 {
 726         int r;
 727
 728         r = misc_register(&_autofs_dev_ioctl_misc);
 729         if (r) {
 730                 pr_err("misc_register failed for control device\n");
 731                 return r;
 732         }
 733
 734         return 0;
 735 }
 736
 737 void autofs_dev_ioctl_exit(void)
 738 {
 739         misc_deregister(&_autofs_dev_ioctl_misc);
 740 }