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         return memdup_user(in, tmp.size);
 107 }
 108
 109 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 110 {
 111         kfree(param);
 112         return;
 113 }
 114
 115 /*
 116  * Check sanity of parameter control fields and if a path is present
 117  * check that it is terminated and contains at least one "/".
 118  */
 119 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 120 {
 121         int err;
 122
 123         err = check_dev_ioctl_version(cmd, param);
 124         if (err) {
 125                 AUTOFS_WARN("invalid device control module version "
 126                      "supplied for cmd(0x%08x)", cmd);
 127                 goto out;
 128         }
 129
 130         if (param->size > sizeof(*param)) {
 131                 err = invalid_str(param->path, param->size - sizeof(*param));
 132                 if (err) {
 133                         AUTOFS_WARN(
 134                           "path string terminator missing for cmd(0x%08x)",
 135                           cmd);
 136                         goto out;
 137                 }
 138
 139                 err = check_name(param->path);
 140                 if (err) {
 141                         AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 142                                     cmd);
 143                         goto out;
 144                 }
 145         }
 146
 147         err = 0;
 148 out:
 149         return err;
 150 }
 151
 152 /*
 153  * Get the autofs super block info struct from the file opened on
 154  * the autofs mount point.
 155  */
 156 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 157 {
 158         struct autofs_sb_info *sbi = NULL;
 159         struct inode *inode;
 160
 161         if (f) {
 162                 inode = file_inode(f);
 163                 sbi = autofs4_sbi(inode->i_sb);
 164         }
 165         return sbi;
 166 }
 167
 168 /* Return autofs module protocol version */
 169 static int autofs_dev_ioctl_protover(struct file *fp,
 170                                      struct autofs_sb_info *sbi,
 171                                      struct autofs_dev_ioctl *param)
 172 {
 173         param->protover.version = sbi->version;
 174         return 0;
 175 }
 176
 177 /* Return autofs module protocol sub version */
 178 static int autofs_dev_ioctl_protosubver(struct file *fp,
 179                                         struct autofs_sb_info *sbi,
 180                                         struct autofs_dev_ioctl *param)
 181 {
 182         param->protosubver.sub_version = sbi->sub_version;
 183         return 0;
 184 }
 185
 186 /* Find the topmost mount satisfying test() */
 187 static int find_autofs_mount(const char *pathname,
 188                              struct path *res,
 189                              int test(struct path *path, void *data),
 190                              void *data)
 191 {
 192         struct path path;
 193         int err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 194         if (err)
 195                 return err;
 196         err = -ENOENT;
 197         while (path.dentry == path.mnt->mnt_root) {
 198                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 199                         if (test(&path, data)) {
 200                                 path_get(&path);
 201                                 *res = path;
 202                                 err = 0;
 203                                 break;
 204                         }
 205                 }
 206                 if (!follow_up(&path))
 207                         break;
 208         }
 209         path_put(&path);
 210         return err;
 211 }
 212
 213 static int test_by_dev(struct path *path, void *p)
 214 {
 215         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 216 }
 217
 218 static int test_by_type(struct path *path, void *p)
 219 {
 220         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 221         return ino && ino->sbi->type & *(unsigned *)p;
 222 }
 223
 224 /*
 225  * Open a file descriptor on the autofs mount point corresponding
 226  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 227  */
 228 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 229 {
 230         int err, fd;
 231
 232         fd = get_unused_fd_flags(O_CLOEXEC);
 233         if (likely(fd >= 0)) {
 234                 struct file *filp;
 235                 struct path path;
 236
 237                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 238                 if (err)
 239                         goto out;
 240
 241                 /*
 242                  * Find autofs super block that has the device number
 243                  * corresponding to the autofs fs we want to open.
 244                  */
 245
 246                 filp = dentry_open(&path, O_RDONLY, current_cred());
 247                 path_put(&path);
 248                 if (IS_ERR(filp)) {
 249                         err = PTR_ERR(filp);
 250                         goto out;
 251                 }
 252
 253                 fd_install(fd, filp);
 254         }
 255
 256         return fd;
 257
 258 out:
 259         put_unused_fd(fd);
 260         return err;
 261 }
 262
 263 /* Open a file descriptor on an autofs mount point */
 264 static int autofs_dev_ioctl_openmount(struct file *fp,
 265                                       struct autofs_sb_info *sbi,
 266                                       struct autofs_dev_ioctl *param)
 267 {
 268         const char *path;
 269         dev_t devid;
 270         int err, fd;
 271
 272         /* param->path has already been checked */
 273         if (!param->openmount.devid)
 274                 return -EINVAL;
 275
 276         param->ioctlfd = -1;
 277
 278         path = param->path;
 279         devid = new_decode_dev(param->openmount.devid);
 280
 281         err = 0;
 282         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 283         if (unlikely(fd < 0)) {
 284                 err = fd;
 285                 goto out;
 286         }
 287
 288         param->ioctlfd = fd;
 289 out:
 290         return err;
 291 }
 292
 293 /* Close file descriptor allocated above (user can also use close(2)). */
 294 static int autofs_dev_ioctl_closemount(struct file *fp,
 295                                        struct autofs_sb_info *sbi,
 296                                        struct autofs_dev_ioctl *param)
 297 {
 298         return sys_close(param->ioctlfd);
 299 }
 300
 301 /*
 302  * Send "ready" status for an existing wait (either a mount or an expire
 303  * request).
 304  */
 305 static int autofs_dev_ioctl_ready(struct file *fp,
 306                                   struct autofs_sb_info *sbi,
 307                                   struct autofs_dev_ioctl *param)
 308 {
 309         autofs_wqt_t token;
 310
 311         token = (autofs_wqt_t) param->ready.token;
 312         return autofs4_wait_release(sbi, token, 0);
 313 }
 314
 315 /*
 316  * Send "fail" status for an existing wait (either a mount or an expire
 317  * request).
 318  */
 319 static int autofs_dev_ioctl_fail(struct file *fp,
 320                                  struct autofs_sb_info *sbi,
 321                                  struct autofs_dev_ioctl *param)
 322 {
 323         autofs_wqt_t token;
 324         int status;
 325
 326         token = (autofs_wqt_t) param->fail.token;
 327         status = param->fail.status ? param->fail.status : -ENOENT;
 328         return autofs4_wait_release(sbi, token, status);
 329 }
 330
 331 /*
 332  * Set the pipe fd for kernel communication to the daemon.
 333  *
 334  * Normally this is set at mount using an option but if we
 335  * are reconnecting to a busy mount then we need to use this
 336  * to tell the autofs mount about the new kernel pipe fd. In
 337  * order to protect mounts against incorrectly setting the
 338  * pipefd we also require that the autofs mount be catatonic.
 339  *
 340  * This also sets the process group id used to identify the
 341  * controlling process (eg. the owning automount(8) daemon).
 342  */
 343 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 344                                       struct autofs_sb_info *sbi,
 345                                       struct autofs_dev_ioctl *param)
 346 {
 347         int pipefd;
 348         int err = 0;
 349         struct pid *new_pid = NULL;
 350
 351         if (param->setpipefd.pipefd == -1)
 352                 return -EINVAL;
 353
 354         pipefd = param->setpipefd.pipefd;
 355
 356         mutex_lock(&sbi->wq_mutex);
 357         if (!sbi->catatonic) {
 358                 mutex_unlock(&sbi->wq_mutex);
 359                 return -EBUSY;
 360         } else {
 361                 struct file *pipe;
 362
 363                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 364
 365                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 366                         AUTOFS_WARN("Not allowed to change PID namespace");
 367                         err = -EINVAL;
 368                         goto out;
 369                 }
 370
 371                 pipe = fget(pipefd);
 372                 if (!pipe) {
 373                         err = -EBADF;
 374                         goto out;
 375                 }
 376                 if (autofs_prepare_pipe(pipe) < 0) {
 377                         err = -EPIPE;
 378                         fput(pipe);
 379                         goto out;
 380                 }
 381                 swap(sbi->oz_pgrp, new_pid);
 382                 sbi->pipefd = pipefd;
 383                 sbi->pipe = pipe;
 384                 sbi->catatonic = 0;
 385         }
 386 out:
 387         put_pid(new_pid);
 388         mutex_unlock(&sbi->wq_mutex);
 389         return err;
 390 }
 391
 392 /*
 393  * Make the autofs mount point catatonic, no longer responsive to
 394  * mount requests. Also closes the kernel pipe file descriptor.
 395  */
 396 static int autofs_dev_ioctl_catatonic(struct file *fp,
 397                                       struct autofs_sb_info *sbi,
 398                                       struct autofs_dev_ioctl *param)
 399 {
 400         autofs4_catatonic_mode(sbi);
 401         return 0;
 402 }
 403
 404 /* Set the autofs mount timeout */
 405 static int autofs_dev_ioctl_timeout(struct file *fp,
 406                                     struct autofs_sb_info *sbi,
 407                                     struct autofs_dev_ioctl *param)
 408 {
 409         unsigned long timeout;
 410
 411         timeout = param->timeout.timeout;
 412         param->timeout.timeout = sbi->exp_timeout / HZ;
 413         sbi->exp_timeout = timeout * HZ;
 414         return 0;
 415 }
 416
 417 /*
 418  * Return the uid and gid of the last request for the mount
 419  *
 420  * When reconstructing an autofs mount tree with active mounts
 421  * we need to re-connect to mounts that may have used the original
 422  * process uid and gid (or string variations of them) for mount
 423  * lookups within the map entry.
 424  */
 425 static int autofs_dev_ioctl_requester(struct file *fp,
 426                                       struct autofs_sb_info *sbi,
 427                                       struct autofs_dev_ioctl *param)
 428 {
 429         struct autofs_info *ino;
 430         struct path path;
 431         dev_t devid;
 432         int err = -ENOENT;
 433
 434         if (param->size <= sizeof(*param)) {
 435                 err = -EINVAL;
 436                 goto out;
 437         }
 438
 439         devid = sbi->sb->s_dev;
 440
 441         param->requester.uid = param->requester.gid = -1;
 442
 443         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 444         if (err)
 445                 goto out;
 446
 447         ino = autofs4_dentry_ino(path.dentry);
 448         if (ino) {
 449                 err = 0;
 450                 autofs4_expire_wait(path.dentry);
 451                 spin_lock(&sbi->fs_lock);
 452                 param->requester.uid = from_kuid_munged(current_user_ns(), ino->uid);
 453                 param->requester.gid = from_kgid_munged(current_user_ns(), ino->gid);
 454                 spin_unlock(&sbi->fs_lock);
 455         }
 456         path_put(&path);
 457 out:
 458         return err;
 459 }
 460
 461 /*
 462  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 463  * more that can be done.
 464  */
 465 static int autofs_dev_ioctl_expire(struct file *fp,
 466                                    struct autofs_sb_info *sbi,
 467                                    struct autofs_dev_ioctl *param)
 468 {
 469         struct vfsmount *mnt;
 470         int how;
 471
 472         how = param->expire.how;
 473         mnt = fp->f_path.mnt;
 474
 475         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 476 }
 477
 478 /* Check if autofs mount point is in use */
 479 static int autofs_dev_ioctl_askumount(struct file *fp,
 480                                       struct autofs_sb_info *sbi,
 481                                       struct autofs_dev_ioctl *param)
 482 {
 483         param->askumount.may_umount = 0;
 484         if (may_umount(fp->f_path.mnt))
 485                 param->askumount.may_umount = 1;
 486         return 0;
 487 }
 488
 489 /*
 490  * Check if the given path is a mountpoint.
 491  *
 492  * If we are supplied with the file descriptor of an autofs
 493  * mount we're looking for a specific mount. In this case
 494  * the path is considered a mountpoint if it is itself a
 495  * mountpoint or contains a mount, such as a multi-mount
 496  * without a root mount. In this case we return 1 if the
 497  * path is a mount point and the super magic of the covering
 498  * mount if there is one or 0 if it isn't a mountpoint.
 499  *
 500  * If we aren't supplied with a file descriptor then we
 501  * lookup the path and check if it is the root of a mount.
 502  * If a type is given we are looking for a particular autofs
 503  * mount and if we don't find a match we return fail. If the
 504  * located path is the root of a mount we return 1 along with
 505  * the super magic of the mount or 0 otherwise.
 506  *
 507  * In both cases the the device number (as returned by
 508  * new_encode_dev()) is also returned.
 509  */
 510 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 511                                          struct autofs_sb_info *sbi,
 512                                          struct autofs_dev_ioctl *param)
 513 {
 514         struct path path;
 515         const char *name;
 516         unsigned int type;
 517         unsigned int devid, magic;
 518         int err = -ENOENT;
 519
 520         if (param->size <= sizeof(*param)) {
 521                 err = -EINVAL;
 522                 goto out;
 523         }
 524
 525         name = param->path;
 526         type = param->ismountpoint.in.type;
 527
 528         param->ismountpoint.out.devid = devid = 0;
 529         param->ismountpoint.out.magic = magic = 0;
 530
 531         if (!fp || param->ioctlfd == -1) {
 532                 if (autofs_type_any(type))
 533                         err = kern_path_mountpoint(AT_FDCWD,
 534                                                    name, &path, LOOKUP_FOLLOW);
 535                 else
 536                         err = find_autofs_mount(name, &path,
 537                                                 test_by_type, &type);
 538                 if (err)
 539                         goto out;
 540                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 541                 err = 0;
 542                 if (path.mnt->mnt_root == path.dentry) {
 543                         err = 1;
 544                         magic = path.dentry->d_sb->s_magic;
 545                 }
 546         } else {
 547                 dev_t dev = sbi->sb->s_dev;
 548
 549                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 550                 if (err)
 551                         goto out;
 552
 553                 devid = new_encode_dev(dev);
 554
 555                 err = have_submounts(path.dentry);
 556
 557                 if (follow_down_one(&path))
 558                         magic = path.dentry->d_sb->s_magic;
 559         }
 560
 561         param->ismountpoint.out.devid = devid;
 562         param->ismountpoint.out.magic = magic;
 563         path_put(&path);
 564 out:
 565         return err;
 566 }
 567
 568 /*
 569  * Our range of ioctl numbers isn't 0 based so we need to shift
 570  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 571  * lookup.
 572  */
 573 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 574
 575 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 576 {
 577         static struct {
 578                 int cmd;
 579                 ioctl_fn fn;
 580         } _ioctls[] = {
 581                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 582                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 583                          autofs_dev_ioctl_protover},
 584                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 585                          autofs_dev_ioctl_protosubver},
 586                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 587                          autofs_dev_ioctl_openmount},
 588                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 589                          autofs_dev_ioctl_closemount},
 590                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 591                          autofs_dev_ioctl_ready},
 592                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 593                          autofs_dev_ioctl_fail},
 594                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 595                          autofs_dev_ioctl_setpipefd},
 596                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 597                          autofs_dev_ioctl_catatonic},
 598                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 599                          autofs_dev_ioctl_timeout},
 600                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 601                          autofs_dev_ioctl_requester},
 602                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 603                          autofs_dev_ioctl_expire},
 604                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 605                          autofs_dev_ioctl_askumount},
 606                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 607                          autofs_dev_ioctl_ismountpoint}
 608         };
 609         unsigned int idx = cmd_idx(cmd);
 610
 611         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 612 }
 613
 614 /* ioctl dispatcher */
 615 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 616 {
 617         struct autofs_dev_ioctl *param;
 618         struct file *fp;
 619         struct autofs_sb_info *sbi;
 620         unsigned int cmd_first, cmd;
 621         ioctl_fn fn = NULL;
 622         int err = 0;
 623
 624         /* only root can play with this */
 625         if (!capable(CAP_SYS_ADMIN))
 626                 return -EPERM;
 627
 628         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 629         cmd = _IOC_NR(command);
 630
 631         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 632             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 633                 return -ENOTTY;
 634         }
 635
 636         /* Copy the parameters into kernel space. */
 637         param = copy_dev_ioctl(user);
 638         if (IS_ERR(param))
 639                 return PTR_ERR(param);
 640
 641         err = validate_dev_ioctl(command, param);
 642         if (err)
 643                 goto out;
 644
 645         /* The validate routine above always sets the version */
 646         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 647                 goto done;
 648
 649         fn = lookup_dev_ioctl(cmd);
 650         if (!fn) {
 651                 AUTOFS_WARN("unknown command 0x%08x", command);
 652                 return -ENOTTY;
 653         }
 654
 655         fp = NULL;
 656         sbi = NULL;
 657
 658         /*
 659          * For obvious reasons the openmount can't have a file
 660          * descriptor yet. We don't take a reference to the
 661          * file during close to allow for immediate release.
 662          */
 663         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 664             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 665                 fp = fget(param->ioctlfd);
 666                 if (!fp) {
 667                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 668                                 goto cont;
 669                         err = -EBADF;
 670                         goto out;
 671                 }
 672
 673                 sbi = autofs_dev_ioctl_sbi(fp);
 674                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 675                         err = -EINVAL;
 676                         fput(fp);
 677                         goto out;
 678                 }
 679
 680                 /*
 681                  * Admin needs to be able to set the mount catatonic in
 682                  * order to be able to perform the re-open.
 683                  */
 684                 if (!autofs4_oz_mode(sbi) &&
 685                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 686                         err = -EACCES;
 687                         fput(fp);
 688                         goto out;
 689                 }
 690         }
 691 cont:
 692         err = fn(fp, sbi, param);
 693
 694         if (fp)
 695                 fput(fp);
 696 done:
 697         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 698                 err = -EFAULT;
 699 out:
 700         free_dev_ioctl(param);
 701         return err;
 702 }
 703
 704 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 705 {
 706         int err;
 707         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 708         return (long) err;
 709 }
 710
 711 #ifdef CONFIG_COMPAT
 712 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 713 {
 714         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 715 }
 716 #else
 717 #define autofs_dev_ioctl_compat NULL
 718 #endif
 719
 720 static const struct file_operations _dev_ioctl_fops = {
 721         .unlocked_ioctl  = autofs_dev_ioctl,
 722         .compat_ioctl = autofs_dev_ioctl_compat,
 723         .owner   = THIS_MODULE,
 724         .llseek = noop_llseek,
 725 };
 726
 727 static struct miscdevice _autofs_dev_ioctl_misc = {
 728         .minor          = AUTOFS_MINOR,
 729         .name           = AUTOFS_DEVICE_NAME,
 730         .fops           = &_dev_ioctl_fops
 731 };
 732
 733 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 734 MODULE_ALIAS("devname:autofs");
 735
 736 /* Register/deregister misc character device */
 737 int autofs_dev_ioctl_init(void)
 738 {
 739         int r;
 740
 741         r = misc_register(&_autofs_dev_ioctl_misc);
 742         if (r) {
 743                 AUTOFS_ERROR("misc_register failed for control device");
 744                 return r;
 745         }
 746
 747         return 0;
 748 }
 749
 750 void autofs_dev_ioctl_exit(void)
 751 {
 752         misc_deregister(&_autofs_dev_ioctl_misc);
 753         return;
 754 }
 755