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/cred.h>
  21 #include <linux/compat.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/magic.h>
  24 #include <linux/dcache.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/slab.h>
  27
  28 #include "autofs_i.h"
  29
  30 /*
  31  * This module implements an interface for routing autofs ioctl control
  32  * commands via a miscellaneous device file.
  33  *
  34  * The alternate interface is needed because we need to be able open
  35  * an ioctl file descriptor on an autofs mount that may be covered by
  36  * another mount. This situation arises when starting automount(8)
  37  * or other user space daemon which uses direct mounts or offset
  38  * mounts (used for autofs lazy mount/umount of nested mount trees),
  39  * which have been left busy at at service shutdown.
  40  */
  41
  42 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  43                         struct autofs_dev_ioctl *);
  44
  45 static int check_name(const char *name)
  46 {
  47         if (!strchr(name, '/'))
  48                 return -EINVAL;
  49         return 0;
  50 }
  51
  52 /*
  53  * Check a string doesn't overrun the chunk of
  54  * memory we copied from user land.
  55  */
  56 static int invalid_str(char *str, size_t size)
  57 {
  58         if (memchr(str, 0, size))
  59                 return 0;
  60         return -EINVAL;
  61 }
  62
  63 /*
  64  * Check that the user compiled against correct version of autofs
  65  * misc device code.
  66  *
  67  * As well as checking the version compatibility this always copies
  68  * the kernel interface version out.
  69  */
  70 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  71 {
  72         int err = 0;
  73
  74         if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
  75             (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
  76                 pr_warn("ioctl control interface version mismatch: "
  77                         "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
  78                         AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  79                         AUTOFS_DEV_IOCTL_VERSION_MINOR,
  80                         param->ver_major, param->ver_minor, cmd);
  81                 err = -EINVAL;
  82         }
  83
  84         /* Fill in the kernel version. */
  85         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  86         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  87
  88         return err;
  89 }
  90
  91 /*
  92  * Copy parameter control struct, including a possible path allocated
  93  * at the end of the struct.
  94  */
  95 static struct autofs_dev_ioctl *
  96                 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 }
 120
 121 /*
 122  * Check sanity of parameter control fields and if a path is present
 123  * check that it is terminated and contains at least one "/".
 124  */
 125 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 126 {
 127         int err;
 128
 129         err = check_dev_ioctl_version(cmd, param);
 130         if (err) {
 131                 pr_warn("invalid device control module version "
 132                         "supplied for cmd(0x%08x)\n", cmd);
 133                 goto out;
 134         }
 135
 136         if (param->size > sizeof(*param)) {
 137                 err = invalid_str(param->path, param->size - sizeof(*param));
 138                 if (err) {
 139                         pr_warn(
 140                           "path string terminator missing for cmd(0x%08x)\n",
 141                           cmd);
 142                         goto out;
 143                 }
 144
 145                 err = check_name(param->path);
 146                 if (err) {
 147                         pr_warn("invalid path supplied for cmd(0x%08x)\n",
 148                                 cmd);
 149                         goto out;
 150                 }
 151         }
 152
 153         err = 0;
 154 out:
 155         return err;
 156 }
 157
 158 /*
 159  * Get the autofs super block info struct from the file opened on
 160  * the autofs mount point.
 161  */
 162 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 163 {
 164         struct autofs_sb_info *sbi = NULL;
 165         struct inode *inode;
 166
 167         if (f) {
 168                 inode = file_inode(f);
 169                 sbi = autofs4_sbi(inode->i_sb);
 170         }
 171         return sbi;
 172 }
 173
 174 /* Return autofs dev ioctl version */
 175 static int autofs_dev_ioctl_version(struct file *fp,
 176                                     struct autofs_sb_info *sbi,
 177                                     struct autofs_dev_ioctl *param)
 178 {
 179         /* This should have already been set. */
 180         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
 181         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
 182         return 0;
 183 }
 184
 185 /* Return autofs module protocol version */
 186 static int autofs_dev_ioctl_protover(struct file *fp,
 187                                      struct autofs_sb_info *sbi,
 188                                      struct autofs_dev_ioctl *param)
 189 {
 190         param->protover.version = sbi->version;
 191         return 0;
 192 }
 193
 194 /* Return autofs module protocol sub version */
 195 static int autofs_dev_ioctl_protosubver(struct file *fp,
 196                                         struct autofs_sb_info *sbi,
 197                                         struct autofs_dev_ioctl *param)
 198 {
 199         param->protosubver.sub_version = sbi->sub_version;
 200         return 0;
 201 }
 202
 203 /* Find the topmost mount satisfying test() */
 204 static int find_autofs_mount(const char *pathname,
 205                              struct path *res,
 206                              int test(const struct path *path, void *data),
 207                              void *data)
 208 {
 209         struct path path;
 210         int err;
 211
 212         err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 213         if (err)
 214                 return err;
 215         err = -ENOENT;
 216         while (path.dentry == path.mnt->mnt_root) {
 217                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 218                         if (test(&path, data)) {
 219                                 path_get(&path);
 220                                 *res = path;
 221                                 err = 0;
 222                                 break;
 223                         }
 224                 }
 225                 if (!follow_up(&path))
 226                         break;
 227         }
 228         path_put(&path);
 229         return err;
 230 }
 231
 232 static int test_by_dev(const struct path *path, void *p)
 233 {
 234         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 235 }
 236
 237 static int test_by_type(const struct path *path, void *p)
 238 {
 239         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 240
 241         return ino && ino->sbi->type & *(unsigned *)p;
 242 }
 243
 244 /*
 245  * Open a file descriptor on the autofs mount point corresponding
 246  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 247  */
 248 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 249 {
 250         int err, fd;
 251
 252         fd = get_unused_fd_flags(O_CLOEXEC);
 253         if (likely(fd >= 0)) {
 254                 struct file *filp;
 255                 struct path path;
 256
 257                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 258                 if (err)
 259                         goto out;
 260
 261                 /*
 262                  * Find autofs super block that has the device number
 263                  * corresponding to the autofs fs we want to open.
 264                  */
 265
 266                 filp = dentry_open(&path, O_RDONLY, current_cred());
 267                 path_put(&path);
 268                 if (IS_ERR(filp)) {
 269                         err = PTR_ERR(filp);
 270                         goto out;
 271                 }
 272
 273                 fd_install(fd, filp);
 274         }
 275
 276         return fd;
 277
 278 out:
 279         put_unused_fd(fd);
 280         return err;
 281 }
 282
 283 /* Open a file descriptor on an autofs mount point */
 284 static int autofs_dev_ioctl_openmount(struct file *fp,
 285                                       struct autofs_sb_info *sbi,
 286                                       struct autofs_dev_ioctl *param)
 287 {
 288         const char *path;
 289         dev_t devid;
 290         int err, fd;
 291
 292         /* param->path has already been checked */
 293         if (!param->openmount.devid)
 294                 return -EINVAL;
 295
 296         param->ioctlfd = -1;
 297
 298         path = param->path;
 299         devid = new_decode_dev(param->openmount.devid);
 300
 301         err = 0;
 302         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 303         if (unlikely(fd < 0)) {
 304                 err = fd;
 305                 goto out;
 306         }
 307
 308         param->ioctlfd = fd;
 309 out:
 310         return err;
 311 }
 312
 313 /* Close file descriptor allocated above (user can also use close(2)). */
 314 static int autofs_dev_ioctl_closemount(struct file *fp,
 315                                        struct autofs_sb_info *sbi,
 316                                        struct autofs_dev_ioctl *param)
 317 {
 318         return sys_close(param->ioctlfd);
 319 }
 320
 321 /*
 322  * Send "ready" status for an existing wait (either a mount or an expire
 323  * request).
 324  */
 325 static int autofs_dev_ioctl_ready(struct file *fp,
 326                                   struct autofs_sb_info *sbi,
 327                                   struct autofs_dev_ioctl *param)
 328 {
 329         autofs_wqt_t token;
 330
 331         token = (autofs_wqt_t) param->ready.token;
 332         return autofs4_wait_release(sbi, token, 0);
 333 }
 334
 335 /*
 336  * Send "fail" status for an existing wait (either a mount or an expire
 337  * request).
 338  */
 339 static int autofs_dev_ioctl_fail(struct file *fp,
 340                                  struct autofs_sb_info *sbi,
 341                                  struct autofs_dev_ioctl *param)
 342 {
 343         autofs_wqt_t token;
 344         int status;
 345
 346         token = (autofs_wqt_t) param->fail.token;
 347         status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 348         return autofs4_wait_release(sbi, token, status);
 349 }
 350
 351 /*
 352  * Set the pipe fd for kernel communication to the daemon.
 353  *
 354  * Normally this is set at mount using an option but if we
 355  * are reconnecting to a busy mount then we need to use this
 356  * to tell the autofs mount about the new kernel pipe fd. In
 357  * order to protect mounts against incorrectly setting the
 358  * pipefd we also require that the autofs mount be catatonic.
 359  *
 360  * This also sets the process group id used to identify the
 361  * controlling process (eg. the owning automount(8) daemon).
 362  */
 363 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 364                                       struct autofs_sb_info *sbi,
 365                                       struct autofs_dev_ioctl *param)
 366 {
 367         int pipefd;
 368         int err = 0;
 369         struct pid *new_pid = NULL;
 370
 371         if (param->setpipefd.pipefd == -1)
 372                 return -EINVAL;
 373
 374         pipefd = param->setpipefd.pipefd;
 375
 376         mutex_lock(&sbi->wq_mutex);
 377         if (!sbi->catatonic) {
 378                 mutex_unlock(&sbi->wq_mutex);
 379                 return -EBUSY;
 380         } else {
 381                 struct file *pipe;
 382
 383                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 384
 385                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 386                         pr_warn("not allowed to change PID namespace\n");
 387                         err = -EINVAL;
 388                         goto out;
 389                 }
 390
 391                 pipe = fget(pipefd);
 392                 if (!pipe) {
 393                         err = -EBADF;
 394                         goto out;
 395                 }
 396                 if (autofs_prepare_pipe(pipe) < 0) {
 397                         err = -EPIPE;
 398                         fput(pipe);
 399                         goto out;
 400                 }
 401                 swap(sbi->oz_pgrp, new_pid);
 402                 sbi->pipefd = pipefd;
 403                 sbi->pipe = pipe;
 404                 sbi->catatonic = 0;
 405         }
 406 out:
 407         put_pid(new_pid);
 408         mutex_unlock(&sbi->wq_mutex);
 409         return err;
 410 }
 411
 412 /*
 413  * Make the autofs mount point catatonic, no longer responsive to
 414  * mount requests. Also closes the kernel pipe file descriptor.
 415  */
 416 static int autofs_dev_ioctl_catatonic(struct file *fp,
 417                                       struct autofs_sb_info *sbi,
 418                                       struct autofs_dev_ioctl *param)
 419 {
 420         autofs4_catatonic_mode(sbi);
 421         return 0;
 422 }
 423
 424 /* Set the autofs mount timeout */
 425 static int autofs_dev_ioctl_timeout(struct file *fp,
 426                                     struct autofs_sb_info *sbi,
 427                                     struct autofs_dev_ioctl *param)
 428 {
 429         unsigned long timeout;
 430
 431         timeout = param->timeout.timeout;
 432         param->timeout.timeout = sbi->exp_timeout / HZ;
 433         sbi->exp_timeout = timeout * HZ;
 434         return 0;
 435 }
 436
 437 /*
 438  * Return the uid and gid of the last request for the mount
 439  *
 440  * When reconstructing an autofs mount tree with active mounts
 441  * we need to re-connect to mounts that may have used the original
 442  * process uid and gid (or string variations of them) for mount
 443  * lookups within the map entry.
 444  */
 445 static int autofs_dev_ioctl_requester(struct file *fp,
 446                                       struct autofs_sb_info *sbi,
 447                                       struct autofs_dev_ioctl *param)
 448 {
 449         struct autofs_info *ino;
 450         struct path path;
 451         dev_t devid;
 452         int err = -ENOENT;
 453
 454         if (param->size <= sizeof(*param)) {
 455                 err = -EINVAL;
 456                 goto out;
 457         }
 458
 459         devid = sbi->sb->s_dev;
 460
 461         param->requester.uid = param->requester.gid = -1;
 462
 463         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 464         if (err)
 465                 goto out;
 466
 467         ino = autofs4_dentry_ino(path.dentry);
 468         if (ino) {
 469                 err = 0;
 470                 autofs4_expire_wait(&path, 0);
 471                 spin_lock(&sbi->fs_lock);
 472                 param->requester.uid =
 473                         from_kuid_munged(current_user_ns(), ino->uid);
 474                 param->requester.gid =
 475                         from_kgid_munged(current_user_ns(), ino->gid);
 476                 spin_unlock(&sbi->fs_lock);
 477         }
 478         path_put(&path);
 479 out:
 480         return err;
 481 }
 482
 483 /*
 484  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 485  * more that can be done.
 486  */
 487 static int autofs_dev_ioctl_expire(struct file *fp,
 488                                    struct autofs_sb_info *sbi,
 489                                    struct autofs_dev_ioctl *param)
 490 {
 491         struct vfsmount *mnt;
 492         int how;
 493
 494         how = param->expire.how;
 495         mnt = fp->f_path.mnt;
 496
 497         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 498 }
 499
 500 /* Check if autofs mount point is in use */
 501 static int autofs_dev_ioctl_askumount(struct file *fp,
 502                                       struct autofs_sb_info *sbi,
 503                                       struct autofs_dev_ioctl *param)
 504 {
 505         param->askumount.may_umount = 0;
 506         if (may_umount(fp->f_path.mnt))
 507                 param->askumount.may_umount = 1;
 508         return 0;
 509 }
 510
 511 /*
 512  * Check if the given path is a mountpoint.
 513  *
 514  * If we are supplied with the file descriptor of an autofs
 515  * mount we're looking for a specific mount. In this case
 516  * the path is considered a mountpoint if it is itself a
 517  * mountpoint or contains a mount, such as a multi-mount
 518  * without a root mount. In this case we return 1 if the
 519  * path is a mount point and the super magic of the covering
 520  * mount if there is one or 0 if it isn't a mountpoint.
 521  *
 522  * If we aren't supplied with a file descriptor then we
 523  * lookup the path and check if it is the root of a mount.
 524  * If a type is given we are looking for a particular autofs
 525  * mount and if we don't find a match we return fail. If the
 526  * located path is the root of a mount we return 1 along with
 527  * the super magic of the mount or 0 otherwise.
 528  *
 529  * In both cases the the device number (as returned by
 530  * new_encode_dev()) is also returned.
 531  */
 532 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 533                                          struct autofs_sb_info *sbi,
 534                                          struct autofs_dev_ioctl *param)
 535 {
 536         struct path path;
 537         const char *name;
 538         unsigned int type;
 539         unsigned int devid, magic;
 540         int err = -ENOENT;
 541
 542         if (param->size <= sizeof(*param)) {
 543                 err = -EINVAL;
 544                 goto out;
 545         }
 546
 547         name = param->path;
 548         type = param->ismountpoint.in.type;
 549
 550         param->ismountpoint.out.devid = devid = 0;
 551         param->ismountpoint.out.magic = magic = 0;
 552
 553         if (!fp || param->ioctlfd == -1) {
 554                 if (autofs_type_any(type))
 555                         err = kern_path_mountpoint(AT_FDCWD,
 556                                                    name, &path, LOOKUP_FOLLOW);
 557                 else
 558                         err = find_autofs_mount(name, &path,
 559                                                 test_by_type, &type);
 560                 if (err)
 561                         goto out;
 562                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 563                 err = 0;
 564                 if (path.mnt->mnt_root == path.dentry) {
 565                         err = 1;
 566                         magic = path.dentry->d_sb->s_magic;
 567                 }
 568         } else {
 569                 dev_t dev = sbi->sb->s_dev;
 570
 571                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 572                 if (err)
 573                         goto out;
 574
 575                 devid = new_encode_dev(dev);
 576
 577                 err = path_has_submounts(&path);
 578
 579                 if (follow_down_one(&path))
 580                         magic = path.dentry->d_sb->s_magic;
 581         }
 582
 583         param->ismountpoint.out.devid = devid;
 584         param->ismountpoint.out.magic = magic;
 585         path_put(&path);
 586 out:
 587         return err;
 588 }
 589
 590 /*
 591  * Our range of ioctl numbers isn't 0 based so we need to shift
 592  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 593  * lookup.
 594  */
 595 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 596
 597 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 598 {
 599         static ioctl_fn _ioctls[] = {
 600                 autofs_dev_ioctl_version,
 601                 autofs_dev_ioctl_protover,
 602                 autofs_dev_ioctl_protosubver,
 603                 autofs_dev_ioctl_openmount,
 604                 autofs_dev_ioctl_closemount,
 605                 autofs_dev_ioctl_ready,
 606                 autofs_dev_ioctl_fail,
 607                 autofs_dev_ioctl_setpipefd,
 608                 autofs_dev_ioctl_catatonic,
 609                 autofs_dev_ioctl_timeout,
 610                 autofs_dev_ioctl_requester,
 611                 autofs_dev_ioctl_expire,
 612                 autofs_dev_ioctl_askumount,
 613                 autofs_dev_ioctl_ismountpoint,
 614         };
 615         unsigned int idx = cmd_idx(cmd);
 616
 617         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
 618 }
 619
 620 /* ioctl dispatcher */
 621 static int _autofs_dev_ioctl(unsigned int command,
 622                              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         fn = lookup_dev_ioctl(cmd);
 653         if (!fn) {
 654                 pr_warn("unknown command 0x%08x\n", command);
 655                 err = -ENOTTY;
 656                 goto out;
 657         }
 658
 659         fp = NULL;
 660         sbi = NULL;
 661
 662         /*
 663          * For obvious reasons the openmount can't have a file
 664          * descriptor yet. We don't take a reference to the
 665          * file during close to allow for immediate release,
 666          * and the same for retrieving ioctl version.
 667          */
 668         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 669             cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 670             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 671                 fp = fget(param->ioctlfd);
 672                 if (!fp) {
 673                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 674                                 goto cont;
 675                         err = -EBADF;
 676                         goto out;
 677                 }
 678
 679                 sbi = autofs_dev_ioctl_sbi(fp);
 680                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 681                         err = -EINVAL;
 682                         fput(fp);
 683                         goto out;
 684                 }
 685
 686                 /*
 687                  * Admin needs to be able to set the mount catatonic in
 688                  * order to be able to perform the re-open.
 689                  */
 690                 if (!autofs4_oz_mode(sbi) &&
 691                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 692                         err = -EACCES;
 693                         fput(fp);
 694                         goto out;
 695                 }
 696         }
 697 cont:
 698         err = fn(fp, sbi, param);
 699
 700         if (fp)
 701                 fput(fp);
 702         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 703                 err = -EFAULT;
 704 out:
 705         free_dev_ioctl(param);
 706         return err;
 707 }
 708
 709 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 710 {
 711         int err;
 712
 713         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 714         return (long) err;
 715 }
 716
 717 #ifdef CONFIG_COMPAT
 718 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 719 {
 720         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 721 }
 722 #else
 723 #define autofs_dev_ioctl_compat NULL
 724 #endif
 725
 726 static const struct file_operations _dev_ioctl_fops = {
 727         .unlocked_ioctl  = autofs_dev_ioctl,
 728         .compat_ioctl = autofs_dev_ioctl_compat,
 729         .owner   = THIS_MODULE,
 730         .llseek = noop_llseek,
 731 };
 732
 733 static struct miscdevice _autofs_dev_ioctl_misc = {
 734         .minor          = AUTOFS_MINOR,
 735         .name           = AUTOFS_DEVICE_NAME,
 736         .fops           = &_dev_ioctl_fops
 737 };
 738
 739 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 740 MODULE_ALIAS("devname:autofs");
 741
 742 /* Register/deregister misc character device */
 743 int __init autofs_dev_ioctl_init(void)
 744 {
 745         int r;
 746
 747         r = misc_register(&_autofs_dev_ioctl_misc);
 748         if (r) {
 749                 pr_err("misc_register failed for control device\n");
 750                 return r;
 751         }
 752
 753         return 0;
 754 }
 755
 756 void autofs_dev_ioctl_exit(void)
 757 {
 758         misc_deregister(&_autofs_dev_ioctl_misc);
 759 }