fs/autofs4/dev-ioctl.c

   1 /*
   2  * Copyright 2008 Red Hat, Inc. All rights reserved.
   3  * Copyright 2008 Ian Kent <raven@themaw.net>
   4  *
   5  * This file is part of the Linux kernel and is made available under
   6  * the terms of the GNU General Public License, version 2, or at your
   7  * option, any later version, incorporated herein by reference.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/init.h>
  14 #include <linux/wait.h>
  15 #include <linux/namei.h>
  16 #include <linux/fcntl.h>
  17 #include <linux/file.h>
  18 #include <linux/fdtable.h>
  19 #include <linux/sched.h>
  20 #include <linux/compat.h>
  21 #include <linux/syscalls.h>
  22 #include <linux/magic.h>
  23 #include <linux/dcache.h>
  24 #include <linux/uaccess.h>
  25 #include <linux/slab.h>
  26
  27 #include "autofs_i.h"
  28
  29 /*
  30  * This module implements an interface for routing autofs ioctl control
  31  * commands via a miscellaneous device file.
  32  *
  33  * The alternate interface is needed because we need to be able open
  34  * an ioctl file descriptor on an autofs mount that may be covered by
  35  * another mount. This situation arises when starting automount(8)
  36  * or other user space daemon which uses direct mounts or offset
  37  * mounts (used for autofs lazy mount/umount of nested mount trees),
  38  * which have been left busy at at service shutdown.
  39  */
  40
  41 #define AUTOFS_DEV_IOCTL_SIZE   sizeof(struct autofs_dev_ioctl)
  42
  43 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  44                         struct autofs_dev_ioctl *);
  45
  46 static int check_name(const char *name)
  47 {
  48         if (!strchr(name, '/'))
  49                 return -EINVAL;
  50         return 0;
  51 }
  52
  53 /*
  54  * Check a string doesn't overrun the chunk of
  55  * memory we copied from user land.
  56  */
  57 static int invalid_str(char *str, size_t size)
  58 {
  59         if (memchr(str, 0, size))
  60                 return 0;
  61         return -EINVAL;
  62 }
  63
  64 /*
  65  * Check that the user compiled against correct version of autofs
  66  * misc device code.
  67  *
  68  * As well as checking the version compatibility this always copies
  69  * the kernel interface version out.
  70  */
  71 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  72 {
  73         int err = 0;
  74
  75         if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
  76             (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
  77                 AUTOFS_WARN("ioctl control interface version mismatch: "
  78                      "kernel(%u.%u), user(%u.%u), cmd(%d)",
  79                      AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  80                      AUTOFS_DEV_IOCTL_VERSION_MINOR,
  81                      param->ver_major, param->ver_minor, cmd);
  82                 err = -EINVAL;
  83         }
  84
  85         /* Fill in the kernel version. */
  86         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  87         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  88
  89         return err;
  90 }
  91
  92 /*
  93  * Copy parameter control struct, including a possible path allocated
  94  * at the end of the struct.
  95  */
  96 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  97 {
  98         struct autofs_dev_ioctl tmp;
  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         return memdup_user(in, tmp.size);
 110 }
 111
 112 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 113 {
 114         kfree(param);
 115         return;
 116 }
 117
 118 /*
 119  * Check sanity of parameter control fields and if a path is present
 120  * check that it is terminated and contains at least one "/".
 121  */
 122 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 123 {
 124         int err;
 125
 126         err = check_dev_ioctl_version(cmd, param);
 127         if (err) {
 128                 AUTOFS_WARN("invalid device control module version "
 129                      "supplied for cmd(0x%08x)", cmd);
 130                 goto out;
 131         }
 132
 133         if (param->size > sizeof(*param)) {
 134                 err = invalid_str(param->path, param->size - sizeof(*param));
 135                 if (err) {
 136                         AUTOFS_WARN(
 137                           "path string terminator missing for cmd(0x%08x)",
 138                           cmd);
 139                         goto out;
 140                 }
 141
 142                 err = check_name(param->path);
 143                 if (err) {
 144                         AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 145                                     cmd);
 146                         goto out;
 147                 }
 148         }
 149
 150         err = 0;
 151 out:
 152         return err;
 153 }
 154
 155 /*
 156  * Get the autofs super block info struct from the file opened on
 157  * the autofs mount point.
 158  */
 159 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 160 {
 161         struct autofs_sb_info *sbi = NULL;
 162         struct inode *inode;
 163
 164         if (f) {
 165                 inode = file_inode(f);
 166                 sbi = autofs4_sbi(inode->i_sb);
 167         }
 168         return sbi;
 169 }
 170
 171 /* Return autofs module protocol version */
 172 static int autofs_dev_ioctl_protover(struct file *fp,
 173                                      struct autofs_sb_info *sbi,
 174                                      struct autofs_dev_ioctl *param)
 175 {
 176         param->protover.version = sbi->version;
 177         return 0;
 178 }
 179
 180 /* Return autofs module protocol sub version */
 181 static int autofs_dev_ioctl_protosubver(struct file *fp,
 182                                         struct autofs_sb_info *sbi,
 183                                         struct autofs_dev_ioctl *param)
 184 {
 185         param->protosubver.sub_version = sbi->sub_version;
 186         return 0;
 187 }
 188
 189 /* Find the topmost mount satisfying test() */
 190 static int find_autofs_mount(const char *pathname,
 191                              struct path *res,
 192                              int test(struct path *path, void *data),
 193                              void *data)
 194 {
 195         struct path path;
 196         int err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 197         if (err)
 198                 return err;
 199         err = -ENOENT;
 200         while (path.dentry == path.mnt->mnt_root) {
 201                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 202                         if (test(&path, data)) {
 203                                 path_get(&path);
 204                                 *res = path;
 205                                 err = 0;
 206                                 break;
 207                         }
 208                 }
 209                 if (!follow_up(&path))
 210                         break;
 211         }
 212         path_put(&path);
 213         return err;
 214 }
 215
 216 static int test_by_dev(struct path *path, void *p)
 217 {
 218         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 219 }
 220
 221 static int test_by_type(struct path *path, void *p)
 222 {
 223         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 224         return ino && ino->sbi->type & *(unsigned *)p;
 225 }
 226
 227 /*
 228  * Open a file descriptor on the autofs mount point corresponding
 229  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 230  */
 231 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 232 {
 233         int err, fd;
 234
 235         fd = get_unused_fd_flags(O_CLOEXEC);
 236         if (likely(fd >= 0)) {
 237                 struct file *filp;
 238                 struct path path;
 239
 240                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 241                 if (err)
 242                         goto out;
 243
 244                 /*
 245                  * Find autofs super block that has the device number
 246                  * corresponding to the autofs fs we want to open.
 247                  */
 248
 249                 filp = dentry_open(&path, O_RDONLY, current_cred());
 250                 path_put(&path);
 251                 if (IS_ERR(filp)) {
 252                         err = PTR_ERR(filp);
 253                         goto out;
 254                 }
 255
 256                 fd_install(fd, filp);
 257         }
 258
 259         return fd;
 260
 261 out:
 262         put_unused_fd(fd);
 263         return err;
 264 }
 265
 266 /* Open a file descriptor on an autofs mount point */
 267 static int autofs_dev_ioctl_openmount(struct file *fp,
 268                                       struct autofs_sb_info *sbi,
 269                                       struct autofs_dev_ioctl *param)
 270 {
 271         const char *path;
 272         dev_t devid;
 273         int err, fd;
 274
 275         /* param->path has already been checked */
 276         if (!param->openmount.devid)
 277                 return -EINVAL;
 278
 279         param->ioctlfd = -1;
 280
 281         path = param->path;
 282         devid = new_decode_dev(param->openmount.devid);
 283
 284         err = 0;
 285         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 286         if (unlikely(fd < 0)) {
 287                 err = fd;
 288                 goto out;
 289         }
 290
 291         param->ioctlfd = fd;
 292 out:
 293         return err;
 294 }
 295
 296 /* Close file descriptor allocated above (user can also use close(2)). */
 297 static int autofs_dev_ioctl_closemount(struct file *fp,
 298                                        struct autofs_sb_info *sbi,
 299                                        struct autofs_dev_ioctl *param)
 300 {
 301         return sys_close(param->ioctlfd);
 302 }
 303
 304 /*
 305  * Send "ready" status for an existing wait (either a mount or an expire
 306  * request).
 307  */
 308 static int autofs_dev_ioctl_ready(struct file *fp,
 309                                   struct autofs_sb_info *sbi,
 310                                   struct autofs_dev_ioctl *param)
 311 {
 312         autofs_wqt_t token;
 313
 314         token = (autofs_wqt_t) param->ready.token;
 315         return autofs4_wait_release(sbi, token, 0);
 316 }
 317
 318 /*
 319  * Send "fail" status for an existing wait (either a mount or an expire
 320  * request).
 321  */
 322 static int autofs_dev_ioctl_fail(struct file *fp,
 323                                  struct autofs_sb_info *sbi,
 324                                  struct autofs_dev_ioctl *param)
 325 {
 326         autofs_wqt_t token;
 327         int status;
 328
 329         token = (autofs_wqt_t) param->fail.token;
 330         status = param->fail.status ? param->fail.status : -ENOENT;
 331         return autofs4_wait_release(sbi, token, status);
 332 }
 333
 334 /*
 335  * Set the pipe fd for kernel communication to the daemon.
 336  *
 337  * Normally this is set at mount using an option but if we
 338  * are reconnecting to a busy mount then we need to use this
 339  * to tell the autofs mount about the new kernel pipe fd. In
 340  * order to protect mounts against incorrectly setting the
 341  * pipefd we also require that the autofs mount be catatonic.
 342  *
 343  * This also sets the process group id used to identify the
 344  * controlling process (eg. the owning automount(8) daemon).
 345  */
 346 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 347                                       struct autofs_sb_info *sbi,
 348                                       struct autofs_dev_ioctl *param)
 349 {
 350         int pipefd;
 351         int err = 0;
 352         struct pid *new_pid = NULL;
 353
 354         if (param->setpipefd.pipefd == -1)
 355                 return -EINVAL;
 356
 357         pipefd = param->setpipefd.pipefd;
 358
 359         mutex_lock(&sbi->wq_mutex);
 360         if (!sbi->catatonic) {
 361                 mutex_unlock(&sbi->wq_mutex);
 362                 return -EBUSY;
 363         } else {
 364                 struct file *pipe;
 365
 366                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 367
 368                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 369                         AUTOFS_WARN("Not allowed to change PID namespace");
 370                         err = -EINVAL;
 371                         goto out;
 372                 }
 373
 374                 pipe = fget(pipefd);
 375                 if (!pipe) {
 376                         err = -EBADF;
 377                         goto out;
 378                 }
 379                 if (autofs_prepare_pipe(pipe) < 0) {
 380                         err = -EPIPE;
 381                         fput(pipe);
 382                         goto out;
 383                 }
 384                 swap(sbi->oz_pgrp, new_pid);
 385                 sbi->pipefd = pipefd;
 386                 sbi->pipe = pipe;
 387                 sbi->catatonic = 0;
 388         }
 389 out:
 390         put_pid(new_pid);
 391         mutex_unlock(&sbi->wq_mutex);
 392         return err;
 393 }
 394
 395 /*
 396  * Make the autofs mount point catatonic, no longer responsive to
 397  * mount requests. Also closes the kernel pipe file descriptor.
 398  */
 399 static int autofs_dev_ioctl_catatonic(struct file *fp,
 400                                       struct autofs_sb_info *sbi,
 401                                       struct autofs_dev_ioctl *param)
 402 {
 403         autofs4_catatonic_mode(sbi);
 404         return 0;
 405 }
 406
 407 /* Set the autofs mount timeout */
 408 static int autofs_dev_ioctl_timeout(struct file *fp,
 409                                     struct autofs_sb_info *sbi,
 410                                     struct autofs_dev_ioctl *param)
 411 {
 412         unsigned long timeout;
 413
 414         timeout = param->timeout.timeout;
 415         param->timeout.timeout = sbi->exp_timeout / HZ;
 416         sbi->exp_timeout = timeout * HZ;
 417         return 0;
 418 }
 419
 420 /*
 421  * Return the uid and gid of the last request for the mount
 422  *
 423  * When reconstructing an autofs mount tree with active mounts
 424  * we need to re-connect to mounts that may have used the original
 425  * process uid and gid (or string variations of them) for mount
 426  * lookups within the map entry.
 427  */
 428 static int autofs_dev_ioctl_requester(struct file *fp,
 429                                       struct autofs_sb_info *sbi,
 430                                       struct autofs_dev_ioctl *param)
 431 {
 432         struct autofs_info *ino;
 433         struct path path;
 434         dev_t devid;
 435         int err = -ENOENT;
 436
 437         if (param->size <= sizeof(*param)) {
 438                 err = -EINVAL;
 439                 goto out;
 440         }
 441
 442         devid = sbi->sb->s_dev;
 443
 444         param->requester.uid = param->requester.gid = -1;
 445
 446         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 447         if (err)
 448                 goto out;
 449
 450         ino = autofs4_dentry_ino(path.dentry);
 451         if (ino) {
 452                 err = 0;
 453                 autofs4_expire_wait(path.dentry, 0);
 454                 spin_lock(&sbi->fs_lock);
 455                 param->requester.uid = from_kuid_munged(current_user_ns(), ino->uid);
 456                 param->requester.gid = from_kgid_munged(current_user_ns(), ino->gid);
 457                 spin_unlock(&sbi->fs_lock);
 458         }
 459         path_put(&path);
 460 out:
 461         return err;
 462 }
 463
 464 /*
 465  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 466  * more that can be done.
 467  */
 468 static int autofs_dev_ioctl_expire(struct file *fp,
 469                                    struct autofs_sb_info *sbi,
 470                                    struct autofs_dev_ioctl *param)
 471 {
 472         struct vfsmount *mnt;
 473         int how;
 474
 475         how = param->expire.how;
 476         mnt = fp->f_path.mnt;
 477
 478         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 479 }
 480
 481 /* Check if autofs mount point is in use */
 482 static int autofs_dev_ioctl_askumount(struct file *fp,
 483                                       struct autofs_sb_info *sbi,
 484                                       struct autofs_dev_ioctl *param)
 485 {
 486         param->askumount.may_umount = 0;
 487         if (may_umount(fp->f_path.mnt))
 488                 param->askumount.may_umount = 1;
 489         return 0;
 490 }
 491
 492 /*
 493  * Check if the given path is a mountpoint.
 494  *
 495  * If we are supplied with the file descriptor of an autofs
 496  * mount we're looking for a specific mount. In this case
 497  * the path is considered a mountpoint if it is itself a
 498  * mountpoint or contains a mount, such as a multi-mount
 499  * without a root mount. In this case we return 1 if the
 500  * path is a mount point and the super magic of the covering
 501  * mount if there is one or 0 if it isn't a mountpoint.
 502  *
 503  * If we aren't supplied with a file descriptor then we
 504  * lookup the path and check if it is the root of a mount.
 505  * If a type is given we are looking for a particular autofs
 506  * mount and if we don't find a match we return fail. If the
 507  * located path is the root of a mount we return 1 along with
 508  * the super magic of the mount or 0 otherwise.
 509  *
 510  * In both cases the the device number (as returned by
 511  * new_encode_dev()) is also returned.
 512  */
 513 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 514                                          struct autofs_sb_info *sbi,
 515                                          struct autofs_dev_ioctl *param)
 516 {
 517         struct path path;
 518         const char *name;
 519         unsigned int type;
 520         unsigned int devid, magic;
 521         int err = -ENOENT;
 522
 523         if (param->size <= sizeof(*param)) {
 524                 err = -EINVAL;
 525                 goto out;
 526         }
 527
 528         name = param->path;
 529         type = param->ismountpoint.in.type;
 530
 531         param->ismountpoint.out.devid = devid = 0;
 532         param->ismountpoint.out.magic = magic = 0;
 533
 534         if (!fp || param->ioctlfd == -1) {
 535                 if (autofs_type_any(type))
 536                         err = kern_path_mountpoint(AT_FDCWD,
 537                                                    name, &path, LOOKUP_FOLLOW);
 538                 else
 539                         err = find_autofs_mount(name, &path,
 540                                                 test_by_type, &type);
 541                 if (err)
 542                         goto out;
 543                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 544                 err = 0;
 545                 if (path.mnt->mnt_root == path.dentry) {
 546                         err = 1;
 547                         magic = path.dentry->d_sb->s_magic;
 548                 }
 549         } else {
 550                 dev_t dev = sbi->sb->s_dev;
 551
 552                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 553                 if (err)
 554                         goto out;
 555
 556                 devid = new_encode_dev(dev);
 557
 558                 err = have_submounts(path.dentry);
 559
 560                 if (follow_down_one(&path))
 561                         magic = path.dentry->d_sb->s_magic;
 562         }
 563
 564         param->ismountpoint.out.devid = devid;
 565         param->ismountpoint.out.magic = magic;
 566         path_put(&path);
 567 out:
 568         return err;
 569 }
 570
 571 /*
 572  * Our range of ioctl numbers isn't 0 based so we need to shift
 573  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 574  * lookup.
 575  */
 576 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 577
 578 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 579 {
 580         static struct {
 581                 int cmd;
 582                 ioctl_fn fn;
 583         } _ioctls[] = {
 584                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 585                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 586                          autofs_dev_ioctl_protover},
 587                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 588                          autofs_dev_ioctl_protosubver},
 589                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 590                          autofs_dev_ioctl_openmount},
 591                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 592                          autofs_dev_ioctl_closemount},
 593                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 594                          autofs_dev_ioctl_ready},
 595                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 596                          autofs_dev_ioctl_fail},
 597                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 598                          autofs_dev_ioctl_setpipefd},
 599                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 600                          autofs_dev_ioctl_catatonic},
 601                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 602                          autofs_dev_ioctl_timeout},
 603                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 604                          autofs_dev_ioctl_requester},
 605                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 606                          autofs_dev_ioctl_expire},
 607                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 608                          autofs_dev_ioctl_askumount},
 609                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 610                          autofs_dev_ioctl_ismountpoint}
 611         };
 612         unsigned int idx = cmd_idx(cmd);
 613
 614         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 615 }
 616
 617 /* ioctl dispatcher */
 618 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 619 {
 620         struct autofs_dev_ioctl *param;
 621         struct file *fp;
 622         struct autofs_sb_info *sbi;
 623         unsigned int cmd_first, cmd;
 624         ioctl_fn fn = NULL;
 625         int err = 0;
 626
 627         /* only root can play with this */
 628         if (!capable(CAP_SYS_ADMIN))
 629                 return -EPERM;
 630
 631         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 632         cmd = _IOC_NR(command);
 633
 634         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 635             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 636                 return -ENOTTY;
 637         }
 638
 639         /* Copy the parameters into kernel space. */
 640         param = copy_dev_ioctl(user);
 641         if (IS_ERR(param))
 642                 return PTR_ERR(param);
 643
 644         err = validate_dev_ioctl(command, param);
 645         if (err)
 646                 goto out;
 647
 648         /* The validate routine above always sets the version */
 649         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 650                 goto done;
 651
 652         fn = lookup_dev_ioctl(cmd);
 653         if (!fn) {
 654                 AUTOFS_WARN("unknown command 0x%08x", command);
 655                 return -ENOTTY;
 656         }
 657
 658         fp = NULL;
 659         sbi = NULL;
 660
 661         /*
 662          * For obvious reasons the openmount can't have a file
 663          * descriptor yet. We don't take a reference to the
 664          * file during close to allow for immediate release.
 665          */
 666         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 667             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 668                 fp = fget(param->ioctlfd);
 669                 if (!fp) {
 670                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 671                                 goto cont;
 672                         err = -EBADF;
 673                         goto out;
 674                 }
 675
 676                 sbi = autofs_dev_ioctl_sbi(fp);
 677                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 678                         err = -EINVAL;
 679                         fput(fp);
 680                         goto out;
 681                 }
 682
 683                 /*
 684                  * Admin needs to be able to set the mount catatonic in
 685                  * order to be able to perform the re-open.
 686                  */
 687                 if (!autofs4_oz_mode(sbi) &&
 688                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 689                         err = -EACCES;
 690                         fput(fp);
 691                         goto out;
 692                 }
 693         }
 694 cont:
 695         err = fn(fp, sbi, param);
 696
 697         if (fp)
 698                 fput(fp);
 699 done:
 700         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 701                 err = -EFAULT;
 702 out:
 703         free_dev_ioctl(param);
 704         return err;
 705 }
 706
 707 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 708 {
 709         int err;
 710         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 711         return (long) err;
 712 }
 713
 714 #ifdef CONFIG_COMPAT
 715 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 716 {
 717         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 718 }
 719 #else
 720 #define autofs_dev_ioctl_compat NULL
 721 #endif
 722
 723 static const struct file_operations _dev_ioctl_fops = {
 724         .unlocked_ioctl  = autofs_dev_ioctl,
 725         .compat_ioctl = autofs_dev_ioctl_compat,
 726         .owner   = THIS_MODULE,
 727         .llseek = noop_llseek,
 728 };
 729
 730 static struct miscdevice _autofs_dev_ioctl_misc = {
 731         .minor          = AUTOFS_MINOR,
 732         .name           = AUTOFS_DEVICE_NAME,
 733         .fops           = &_dev_ioctl_fops
 734 };
 735
 736 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 737 MODULE_ALIAS("devname:autofs");
 738
 739 /* Register/deregister misc character device */
 740 int __init autofs_dev_ioctl_init(void)
 741 {
 742         int r;
 743
 744         r = misc_register(&_autofs_dev_ioctl_misc);
 745         if (r) {
 746                 AUTOFS_ERROR("misc_register failed for control device");
 747                 return r;
 748         }
 749
 750         return 0;
 751 }
 752
 753 void autofs_dev_ioctl_exit(void)
 754 {
 755         misc_deregister(&_autofs_dev_ioctl_misc);
 756         return;
 757 }
 758