fs/autofs/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/miscdevice.h>
  11 #include <linux/compat.h>
  12 #include <linux/syscalls.h>
  13 #include <linux/magic.h>
  14
  15 #include "autofs_i.h"
  16
  17 /*
  18  * This module implements an interface for routing autofs ioctl control
  19  * commands via a miscellaneous device file.
  20  *
  21  * The alternate interface is needed because we need to be able open
  22  * an ioctl file descriptor on an autofs mount that may be covered by
  23  * another mount. This situation arises when starting automount(8)
  24  * or other user space daemon which uses direct mounts or offset
  25  * mounts (used for autofs lazy mount/umount of nested mount trees),
  26  * which have been left busy at at service shutdown.
  27  */
  28
  29 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  30                         struct autofs_dev_ioctl *);
  31
  32 static int check_name(const char *name)
  33 {
  34         if (!strchr(name, '/'))
  35                 return -EINVAL;
  36         return 0;
  37 }
  38
  39 /*
  40  * Check a string doesn't overrun the chunk of
  41  * memory we copied from user land.
  42  */
  43 static int invalid_str(char *str, size_t size)
  44 {
  45         if (memchr(str, 0, size))
  46                 return 0;
  47         return -EINVAL;
  48 }
  49
  50 /*
  51  * Check that the user compiled against correct version of autofs
  52  * misc device code.
  53  *
  54  * As well as checking the version compatibility this always copies
  55  * the kernel interface version out.
  56  */
  57 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  58 {
  59         int err = 0;
  60
  61         if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
  62             (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
  63                 pr_warn("ioctl control interface version mismatch: "
  64                         "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
  65                         AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  66                         AUTOFS_DEV_IOCTL_VERSION_MINOR,
  67                         param->ver_major, param->ver_minor, cmd);
  68                 err = -EINVAL;
  69         }
  70
  71         /* Fill in the kernel version. */
  72         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  73         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  74
  75         return err;
  76 }
  77
  78 /*
  79  * Copy parameter control struct, including a possible path allocated
  80  * at the end of the struct.
  81  */
  82 static struct autofs_dev_ioctl *
  83 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  84 {
  85         struct autofs_dev_ioctl tmp, *res;
  86
  87         if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
  88                 return ERR_PTR(-EFAULT);
  89
  90         if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
  91                 return ERR_PTR(-EINVAL);
  92
  93         if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
  94                 return ERR_PTR(-ENAMETOOLONG);
  95
  96         res = memdup_user(in, tmp.size);
  97         if (!IS_ERR(res))
  98                 res->size = tmp.size;
  99
 100         return res;
 101 }
 102
 103 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 104 {
 105         kfree(param);
 106 }
 107
 108 /*
 109  * Check sanity of parameter control fields and if a path is present
 110  * check that it is terminated and contains at least one "/".
 111  */
 112 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 113 {
 114         int err;
 115
 116         err = check_dev_ioctl_version(cmd, param);
 117         if (err) {
 118                 pr_warn("invalid device control module version "
 119                         "supplied for cmd(0x%08x)\n", cmd);
 120                 goto out;
 121         }
 122
 123         if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
 124                 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
 125                 if (err) {
 126                         pr_warn(
 127                           "path string terminator missing for cmd(0x%08x)\n",
 128                           cmd);
 129                         goto out;
 130                 }
 131
 132                 err = check_name(param->path);
 133                 if (err) {
 134                         pr_warn("invalid path supplied for cmd(0x%08x)\n",
 135                                 cmd);
 136                         goto out;
 137                 }
 138         } else {
 139                 unsigned int inr = _IOC_NR(cmd);
 140
 141                 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
 142                     inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
 143                     inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
 144                         err = -EINVAL;
 145                         goto out;
 146                 }
 147         }
 148
 149         err = 0;
 150 out:
 151         return err;
 152 }
 153
 154 /*
 155  * Get the autofs super block info struct from the file opened on
 156  * the autofs mount point.
 157  */
 158 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 159 {
 160         struct autofs_sb_info *sbi = NULL;
 161         struct inode *inode;
 162
 163         if (f) {
 164                 inode = file_inode(f);
 165                 sbi = autofs_sbi(inode->i_sb);
 166         }
 167         return sbi;
 168 }
 169
 170 /* Return autofs dev ioctl version */
 171 static int autofs_dev_ioctl_version(struct file *fp,
 172                                     struct autofs_sb_info *sbi,
 173                                     struct autofs_dev_ioctl *param)
 174 {
 175         /* This should have already been set. */
 176         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
 177         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
 178         return 0;
 179 }
 180
 181 /* Return autofs module protocol version */
 182 static int autofs_dev_ioctl_protover(struct file *fp,
 183                                      struct autofs_sb_info *sbi,
 184                                      struct autofs_dev_ioctl *param)
 185 {
 186         param->protover.version = sbi->version;
 187         return 0;
 188 }
 189
 190 /* Return autofs module protocol sub version */
 191 static int autofs_dev_ioctl_protosubver(struct file *fp,
 192                                         struct autofs_sb_info *sbi,
 193                                         struct autofs_dev_ioctl *param)
 194 {
 195         param->protosubver.sub_version = sbi->sub_version;
 196         return 0;
 197 }
 198
 199 /* Find the topmost mount satisfying test() */
 200 static int find_autofs_mount(const char *pathname,
 201                              struct path *res,
 202                              int test(const struct path *path, void *data),
 203                              void *data)
 204 {
 205         struct path path;
 206         int err;
 207
 208         err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 209         if (err)
 210                 return err;
 211         err = -ENOENT;
 212         while (path.dentry == path.mnt->mnt_root) {
 213                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 214                         if (test(&path, data)) {
 215                                 path_get(&path);
 216                                 *res = path;
 217                                 err = 0;
 218                                 break;
 219                         }
 220                 }
 221                 if (!follow_up(&path))
 222                         break;
 223         }
 224         path_put(&path);
 225         return err;
 226 }
 227
 228 static int test_by_dev(const struct path *path, void *p)
 229 {
 230         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 231 }
 232
 233 static int test_by_type(const struct path *path, void *p)
 234 {
 235         struct autofs_info *ino = autofs_dentry_ino(path->dentry);
 236
 237         return ino && ino->sbi->type & *(unsigned *)p;
 238 }
 239
 240 /*
 241  * Open a file descriptor on the autofs mount point corresponding
 242  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 243  */
 244 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 245 {
 246         int err, fd;
 247
 248         fd = get_unused_fd_flags(O_CLOEXEC);
 249         if (likely(fd >= 0)) {
 250                 struct file *filp;
 251                 struct path path;
 252
 253                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 254                 if (err)
 255                         goto out;
 256
 257                 filp = dentry_open(&path, O_RDONLY, current_cred());
 258                 path_put(&path);
 259                 if (IS_ERR(filp)) {
 260                         err = PTR_ERR(filp);
 261                         goto out;
 262                 }
 263
 264                 fd_install(fd, filp);
 265         }
 266
 267         return fd;
 268
 269 out:
 270         put_unused_fd(fd);
 271         return err;
 272 }
 273
 274 /* Open a file descriptor on an autofs mount point */
 275 static int autofs_dev_ioctl_openmount(struct file *fp,
 276                                       struct autofs_sb_info *sbi,
 277                                       struct autofs_dev_ioctl *param)
 278 {
 279         const char *path;
 280         dev_t devid;
 281         int err, fd;
 282
 283         /* param->path has been checked in validate_dev_ioctl() */
 284
 285         if (!param->openmount.devid)
 286                 return -EINVAL;
 287
 288         param->ioctlfd = -1;
 289
 290         path = param->path;
 291         devid = new_decode_dev(param->openmount.devid);
 292
 293         err = 0;
 294         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 295         if (unlikely(fd < 0)) {
 296                 err = fd;
 297                 goto out;
 298         }
 299
 300         param->ioctlfd = fd;
 301 out:
 302         return err;
 303 }
 304
 305 /* Close file descriptor allocated above (user can also use close(2)). */
 306 static int autofs_dev_ioctl_closemount(struct file *fp,
 307                                        struct autofs_sb_info *sbi,
 308                                        struct autofs_dev_ioctl *param)
 309 {
 310         return ksys_close(param->ioctlfd);
 311 }
 312
 313 /*
 314  * Send "ready" status for an existing wait (either a mount or an expire
 315  * request).
 316  */
 317 static int autofs_dev_ioctl_ready(struct file *fp,
 318                                   struct autofs_sb_info *sbi,
 319                                   struct autofs_dev_ioctl *param)
 320 {
 321         autofs_wqt_t token;
 322
 323         token = (autofs_wqt_t) param->ready.token;
 324         return autofs_wait_release(sbi, token, 0);
 325 }
 326
 327 /*
 328  * Send "fail" status for an existing wait (either a mount or an expire
 329  * request).
 330  */
 331 static int autofs_dev_ioctl_fail(struct file *fp,
 332                                  struct autofs_sb_info *sbi,
 333                                  struct autofs_dev_ioctl *param)
 334 {
 335         autofs_wqt_t token;
 336         int status;
 337
 338         token = (autofs_wqt_t) param->fail.token;
 339         status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 340         return autofs_wait_release(sbi, token, status);
 341 }
 342
 343 /*
 344  * Set the pipe fd for kernel communication to the daemon.
 345  *
 346  * Normally this is set at mount using an option but if we
 347  * are reconnecting to a busy mount then we need to use this
 348  * to tell the autofs mount about the new kernel pipe fd. In
 349  * order to protect mounts against incorrectly setting the
 350  * pipefd we also require that the autofs mount be catatonic.
 351  *
 352  * This also sets the process group id used to identify the
 353  * controlling process (eg. the owning automount(8) daemon).
 354  */
 355 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 356                                       struct autofs_sb_info *sbi,
 357                                       struct autofs_dev_ioctl *param)
 358 {
 359         int pipefd;
 360         int err = 0;
 361         struct pid *new_pid = NULL;
 362
 363         if (param->setpipefd.pipefd == -1)
 364                 return -EINVAL;
 365
 366         pipefd = param->setpipefd.pipefd;
 367
 368         mutex_lock(&sbi->wq_mutex);
 369         if (!sbi->catatonic) {
 370                 mutex_unlock(&sbi->wq_mutex);
 371                 return -EBUSY;
 372         } else {
 373                 struct file *pipe;
 374
 375                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 376
 377                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 378                         pr_warn("not allowed to change PID namespace\n");
 379                         err = -EINVAL;
 380                         goto out;
 381                 }
 382
 383                 pipe = fget(pipefd);
 384                 if (!pipe) {
 385                         err = -EBADF;
 386                         goto out;
 387                 }
 388                 if (autofs_prepare_pipe(pipe) < 0) {
 389                         err = -EPIPE;
 390                         fput(pipe);
 391                         goto out;
 392                 }
 393                 swap(sbi->oz_pgrp, new_pid);
 394                 sbi->pipefd = pipefd;
 395                 sbi->pipe = pipe;
 396                 sbi->catatonic = 0;
 397         }
 398 out:
 399         put_pid(new_pid);
 400         mutex_unlock(&sbi->wq_mutex);
 401         return err;
 402 }
 403
 404 /*
 405  * Make the autofs mount point catatonic, no longer responsive to
 406  * mount requests. Also closes the kernel pipe file descriptor.
 407  */
 408 static int autofs_dev_ioctl_catatonic(struct file *fp,
 409                                       struct autofs_sb_info *sbi,
 410                                       struct autofs_dev_ioctl *param)
 411 {
 412         autofs_catatonic_mode(sbi);
 413         return 0;
 414 }
 415
 416 /* Set the autofs mount timeout */
 417 static int autofs_dev_ioctl_timeout(struct file *fp,
 418                                     struct autofs_sb_info *sbi,
 419                                     struct autofs_dev_ioctl *param)
 420 {
 421         unsigned long timeout;
 422
 423         timeout = param->timeout.timeout;
 424         param->timeout.timeout = sbi->exp_timeout / HZ;
 425         sbi->exp_timeout = timeout * HZ;
 426         return 0;
 427 }
 428
 429 /*
 430  * Return the uid and gid of the last request for the mount
 431  *
 432  * When reconstructing an autofs mount tree with active mounts
 433  * we need to re-connect to mounts that may have used the original
 434  * process uid and gid (or string variations of them) for mount
 435  * lookups within the map entry.
 436  */
 437 static int autofs_dev_ioctl_requester(struct file *fp,
 438                                       struct autofs_sb_info *sbi,
 439                                       struct autofs_dev_ioctl *param)
 440 {
 441         struct autofs_info *ino;
 442         struct path path;
 443         dev_t devid;
 444         int err = -ENOENT;
 445
 446         /* param->path has been checked in validate_dev_ioctl() */
 447
 448         devid = sbi->sb->s_dev;
 449
 450         param->requester.uid = param->requester.gid = -1;
 451
 452         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 453         if (err)
 454                 goto out;
 455
 456         ino = autofs_dentry_ino(path.dentry);
 457         if (ino) {
 458                 err = 0;
 459                 autofs_expire_wait(&path, 0);
 460                 spin_lock(&sbi->fs_lock);
 461                 param->requester.uid =
 462                         from_kuid_munged(current_user_ns(), ino->uid);
 463                 param->requester.gid =
 464                         from_kgid_munged(current_user_ns(), ino->gid);
 465                 spin_unlock(&sbi->fs_lock);
 466         }
 467         path_put(&path);
 468 out:
 469         return err;
 470 }
 471
 472 /*
 473  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 474  * more that can be done.
 475  */
 476 static int autofs_dev_ioctl_expire(struct file *fp,
 477                                    struct autofs_sb_info *sbi,
 478                                    struct autofs_dev_ioctl *param)
 479 {
 480         struct vfsmount *mnt;
 481         int how;
 482
 483         how = param->expire.how;
 484         mnt = fp->f_path.mnt;
 485
 486         return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
 487 }
 488
 489 /* Check if autofs mount point is in use */
 490 static int autofs_dev_ioctl_askumount(struct file *fp,
 491                                       struct autofs_sb_info *sbi,
 492                                       struct autofs_dev_ioctl *param)
 493 {
 494         param->askumount.may_umount = 0;
 495         if (may_umount(fp->f_path.mnt))
 496                 param->askumount.may_umount = 1;
 497         return 0;
 498 }
 499
 500 /*
 501  * Check if the given path is a mountpoint.
 502  *
 503  * If we are supplied with the file descriptor of an autofs
 504  * mount we're looking for a specific mount. In this case
 505  * the path is considered a mountpoint if it is itself a
 506  * mountpoint or contains a mount, such as a multi-mount
 507  * without a root mount. In this case we return 1 if the
 508  * path is a mount point and the super magic of the covering
 509  * mount if there is one or 0 if it isn't a mountpoint.
 510  *
 511  * If we aren't supplied with a file descriptor then we
 512  * lookup the path and check if it is the root of a mount.
 513  * If a type is given we are looking for a particular autofs
 514  * mount and if we don't find a match we return fail. If the
 515  * located path is the root of a mount we return 1 along with
 516  * the super magic of the mount or 0 otherwise.
 517  *
 518  * In both cases the the device number (as returned by
 519  * new_encode_dev()) is also returned.
 520  */
 521 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 522                                          struct autofs_sb_info *sbi,
 523                                          struct autofs_dev_ioctl *param)
 524 {
 525         struct path path;
 526         const char *name;
 527         unsigned int type;
 528         unsigned int devid, magic;
 529         int err = -ENOENT;
 530
 531         /* param->path has been checked in validate_dev_ioctl() */
 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_mountpoint(AT_FDCWD,
 542                                                    name, &path, LOOKUP_FOLLOW);
 543                 else
 544                         err = find_autofs_mount(name, &path,
 545                                                 test_by_type, &type);
 546                 if (err)
 547                         goto out;
 548                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 549                 err = 0;
 550                 if (path.mnt->mnt_root == path.dentry) {
 551                         err = 1;
 552                         magic = path.dentry->d_sb->s_magic;
 553                 }
 554         } else {
 555                 dev_t dev = sbi->sb->s_dev;
 556
 557                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 558                 if (err)
 559                         goto out;
 560
 561                 devid = new_encode_dev(dev);
 562
 563                 err = path_has_submounts(&path);
 564
 565                 if (follow_down_one(&path))
 566                         magic = path.dentry->d_sb->s_magic;
 567         }
 568
 569         param->ismountpoint.out.devid = devid;
 570         param->ismountpoint.out.magic = magic;
 571         path_put(&path);
 572 out:
 573         return err;
 574 }
 575
 576 /*
 577  * Our range of ioctl numbers isn't 0 based so we need to shift
 578  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 579  * lookup.
 580  */
 581 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 582
 583 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 584 {
 585         static ioctl_fn _ioctls[] = {
 586                 autofs_dev_ioctl_version,
 587                 autofs_dev_ioctl_protover,
 588                 autofs_dev_ioctl_protosubver,
 589                 autofs_dev_ioctl_openmount,
 590                 autofs_dev_ioctl_closemount,
 591                 autofs_dev_ioctl_ready,
 592                 autofs_dev_ioctl_fail,
 593                 autofs_dev_ioctl_setpipefd,
 594                 autofs_dev_ioctl_catatonic,
 595                 autofs_dev_ioctl_timeout,
 596                 autofs_dev_ioctl_requester,
 597                 autofs_dev_ioctl_expire,
 598                 autofs_dev_ioctl_askumount,
 599                 autofs_dev_ioctl_ismountpoint,
 600         };
 601         unsigned int idx = cmd_idx(cmd);
 602
 603         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
 604 }
 605
 606 /* ioctl dispatcher */
 607 static int _autofs_dev_ioctl(unsigned int command,
 608                              struct autofs_dev_ioctl __user *user)
 609 {
 610         struct autofs_dev_ioctl *param;
 611         struct file *fp;
 612         struct autofs_sb_info *sbi;
 613         unsigned int cmd_first, cmd;
 614         ioctl_fn fn = NULL;
 615         int err = 0;
 616
 617         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 618         cmd = _IOC_NR(command);
 619
 620         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 621             cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
 622                 return -ENOTTY;
 623         }
 624
 625         /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
 626          * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
 627          */
 628         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 629             cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
 630             !capable(CAP_SYS_ADMIN))
 631                 return -EPERM;
 632
 633         /* Copy the parameters into kernel space. */
 634         param = copy_dev_ioctl(user);
 635         if (IS_ERR(param))
 636                 return PTR_ERR(param);
 637
 638         err = validate_dev_ioctl(command, param);
 639         if (err)
 640                 goto out;
 641
 642         fn = lookup_dev_ioctl(cmd);
 643         if (!fn) {
 644                 pr_warn("unknown command 0x%08x\n", command);
 645                 err = -ENOTTY;
 646                 goto out;
 647         }
 648
 649         fp = NULL;
 650         sbi = NULL;
 651
 652         /*
 653          * For obvious reasons the openmount can't have a file
 654          * descriptor yet. We don't take a reference to the
 655          * file during close to allow for immediate release,
 656          * and the same for retrieving ioctl version.
 657          */
 658         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 659             cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 660             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 661                 fp = fget(param->ioctlfd);
 662                 if (!fp) {
 663                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 664                                 goto cont;
 665                         err = -EBADF;
 666                         goto out;
 667                 }
 668
 669                 sbi = autofs_dev_ioctl_sbi(fp);
 670                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 671                         err = -EINVAL;
 672                         fput(fp);
 673                         goto out;
 674                 }
 675
 676                 /*
 677                  * Admin needs to be able to set the mount catatonic in
 678                  * order to be able to perform the re-open.
 679                  */
 680                 if (!autofs_oz_mode(sbi) &&
 681                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 682                         err = -EACCES;
 683                         fput(fp);
 684                         goto out;
 685                 }
 686         }
 687 cont:
 688         err = fn(fp, sbi, param);
 689
 690         if (fp)
 691                 fput(fp);
 692         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 693                 err = -EFAULT;
 694 out:
 695         free_dev_ioctl(param);
 696         return err;
 697 }
 698
 699 static long autofs_dev_ioctl(struct file *file, unsigned int command,
 700                              unsigned long u)
 701 {
 702         int err;
 703
 704         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 705         return (long) err;
 706 }
 707
 708 #ifdef CONFIG_COMPAT
 709 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
 710                                     unsigned long u)
 711 {
 712         return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
 713 }
 714 #else
 715 #define autofs_dev_ioctl_compat NULL
 716 #endif
 717
 718 static const struct file_operations _dev_ioctl_fops = {
 719         .unlocked_ioctl  = autofs_dev_ioctl,
 720         .compat_ioctl = autofs_dev_ioctl_compat,
 721         .owner   = THIS_MODULE,
 722         .llseek = noop_llseek,
 723 };
 724
 725 static struct miscdevice _autofs_dev_ioctl_misc = {
 726         .minor          = AUTOFS_MINOR,
 727         .name           = AUTOFS_DEVICE_NAME,
 728         .fops           = &_dev_ioctl_fops,
 729         .mode           = 0644,
 730 };
 731
 732 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 733 MODULE_ALIAS("devname:autofs");
 734
 735 /* Register/deregister misc character device */
 736 int __init autofs_dev_ioctl_init(void)
 737 {
 738         int r;
 739
 740         r = misc_register(&_autofs_dev_ioctl_misc);
 741         if (r) {
 742                 pr_err("misc_register failed for control device\n");
 743                 return r;
 744         }
 745
 746         return 0;
 747 }
 748
 749 void autofs_dev_ioctl_exit(void)
 750 {
 751         misc_deregister(&_autofs_dev_ioctl_misc);
 752 }