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 ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
  76             (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
  77                 pr_warn("ioctl control interface version mismatch: "
  78                         "kernel(%u.%u), user(%u.%u), cmd(%d)\n",
  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 *
  97                 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  98 {
  99         struct autofs_dev_ioctl tmp, *res;
 100
 101         if (copy_from_user(&tmp, in, sizeof(tmp)))
 102                 return ERR_PTR(-EFAULT);
 103
 104         if (tmp.size < sizeof(tmp))
 105                 return ERR_PTR(-EINVAL);
 106
 107         if (tmp.size > (PATH_MAX + sizeof(tmp)))
 108                 return ERR_PTR(-ENAMETOOLONG);
 109
 110         res = memdup_user(in, tmp.size);
 111         if (!IS_ERR(res))
 112                 res->size = tmp.size;
 113
 114         return res;
 115 }
 116
 117 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 118 {
 119         kfree(param);
 120 }
 121
 122 /*
 123  * Check sanity of parameter control fields and if a path is present
 124  * check that it is terminated and contains at least one "/".
 125  */
 126 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 127 {
 128         int err;
 129
 130         err = check_dev_ioctl_version(cmd, param);
 131         if (err) {
 132                 pr_warn("invalid device control module version "
 133                         "supplied for cmd(0x%08x)\n", cmd);
 134                 goto out;
 135         }
 136
 137         if (param->size > sizeof(*param)) {
 138                 err = invalid_str(param->path, param->size - sizeof(*param));
 139                 if (err) {
 140                         pr_warn(
 141                           "path string terminator missing for cmd(0x%08x)\n",
 142                           cmd);
 143                         goto out;
 144                 }
 145
 146                 err = check_name(param->path);
 147                 if (err) {
 148                         pr_warn("invalid path supplied for cmd(0x%08x)\n",
 149                                 cmd);
 150                         goto out;
 151                 }
 152         }
 153
 154         err = 0;
 155 out:
 156         return err;
 157 }
 158
 159 /*
 160  * Get the autofs super block info struct from the file opened on
 161  * the autofs mount point.
 162  */
 163 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 164 {
 165         struct autofs_sb_info *sbi = NULL;
 166         struct inode *inode;
 167
 168         if (f) {
 169                 inode = file_inode(f);
 170                 sbi = autofs4_sbi(inode->i_sb);
 171         }
 172         return sbi;
 173 }
 174
 175 /* Return autofs module protocol version */
 176 static int autofs_dev_ioctl_protover(struct file *fp,
 177                                      struct autofs_sb_info *sbi,
 178                                      struct autofs_dev_ioctl *param)
 179 {
 180         param->protover.version = sbi->version;
 181         return 0;
 182 }
 183
 184 /* Return autofs module protocol sub version */
 185 static int autofs_dev_ioctl_protosubver(struct file *fp,
 186                                         struct autofs_sb_info *sbi,
 187                                         struct autofs_dev_ioctl *param)
 188 {
 189         param->protosubver.sub_version = sbi->sub_version;
 190         return 0;
 191 }
 192
 193 /* Find the topmost mount satisfying test() */
 194 static int find_autofs_mount(const char *pathname,
 195                              struct path *res,
 196                              int test(struct path *path, void *data),
 197                              void *data)
 198 {
 199         struct path path;
 200         int err;
 201
 202         err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 203         if (err)
 204                 return err;
 205         err = -ENOENT;
 206         while (path.dentry == path.mnt->mnt_root) {
 207                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 208                         if (test(&path, data)) {
 209                                 path_get(&path);
 210                                 *res = path;
 211                                 err = 0;
 212                                 break;
 213                         }
 214                 }
 215                 if (!follow_up(&path))
 216                         break;
 217         }
 218         path_put(&path);
 219         return err;
 220 }
 221
 222 static int test_by_dev(struct path *path, void *p)
 223 {
 224         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 225 }
 226
 227 static int test_by_type(struct path *path, void *p)
 228 {
 229         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 230
 231         return ino && ino->sbi->type & *(unsigned *)p;
 232 }
 233
 234 /*
 235  * Open a file descriptor on the autofs mount point corresponding
 236  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 237  */
 238 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 239 {
 240         int err, fd;
 241
 242         fd = get_unused_fd_flags(O_CLOEXEC);
 243         if (likely(fd >= 0)) {
 244                 struct file *filp;
 245                 struct path path;
 246
 247                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 248                 if (err)
 249                         goto out;
 250
 251                 /*
 252                  * Find autofs super block that has the device number
 253                  * corresponding to the autofs fs we want to open.
 254                  */
 255
 256                 filp = dentry_open(&path, O_RDONLY, current_cred());
 257                 path_put(&path);
 258                 if (IS_ERR(filp)) {
 259                         err = PTR_ERR(filp);
 260                         goto out;
 261                 }
 262
 263                 fd_install(fd, filp);
 264         }
 265
 266         return fd;
 267
 268 out:
 269         put_unused_fd(fd);
 270         return err;
 271 }
 272
 273 /* Open a file descriptor on an autofs mount point */
 274 static int autofs_dev_ioctl_openmount(struct file *fp,
 275                                       struct autofs_sb_info *sbi,
 276                                       struct autofs_dev_ioctl *param)
 277 {
 278         const char *path;
 279         dev_t devid;
 280         int err, fd;
 281
 282         /* param->path has already been checked */
 283         if (!param->openmount.devid)
 284                 return -EINVAL;
 285
 286         param->ioctlfd = -1;
 287
 288         path = param->path;
 289         devid = new_decode_dev(param->openmount.devid);
 290
 291         err = 0;
 292         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 293         if (unlikely(fd < 0)) {
 294                 err = fd;
 295                 goto out;
 296         }
 297
 298         param->ioctlfd = fd;
 299 out:
 300         return err;
 301 }
 302
 303 /* Close file descriptor allocated above (user can also use close(2)). */
 304 static int autofs_dev_ioctl_closemount(struct file *fp,
 305                                        struct autofs_sb_info *sbi,
 306                                        struct autofs_dev_ioctl *param)
 307 {
 308         return sys_close(param->ioctlfd);
 309 }
 310
 311 /*
 312  * Send "ready" status for an existing wait (either a mount or an expire
 313  * request).
 314  */
 315 static int autofs_dev_ioctl_ready(struct file *fp,
 316                                   struct autofs_sb_info *sbi,
 317                                   struct autofs_dev_ioctl *param)
 318 {
 319         autofs_wqt_t token;
 320
 321         token = (autofs_wqt_t) param->ready.token;
 322         return autofs4_wait_release(sbi, token, 0);
 323 }
 324
 325 /*
 326  * Send "fail" status for an existing wait (either a mount or an expire
 327  * request).
 328  */
 329 static int autofs_dev_ioctl_fail(struct file *fp,
 330                                  struct autofs_sb_info *sbi,
 331                                  struct autofs_dev_ioctl *param)
 332 {
 333         autofs_wqt_t token;
 334         int status;
 335
 336         token = (autofs_wqt_t) param->fail.token;
 337         status = param->fail.status ? param->fail.status : -ENOENT;
 338         return autofs4_wait_release(sbi, token, status);
 339 }
 340
 341 /*
 342  * Set the pipe fd for kernel communication to the daemon.
 343  *
 344  * Normally this is set at mount using an option but if we
 345  * are reconnecting to a busy mount then we need to use this
 346  * to tell the autofs mount about the new kernel pipe fd. In
 347  * order to protect mounts against incorrectly setting the
 348  * pipefd we also require that the autofs mount be catatonic.
 349  *
 350  * This also sets the process group id used to identify the
 351  * controlling process (eg. the owning automount(8) daemon).
 352  */
 353 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 354                                       struct autofs_sb_info *sbi,
 355                                       struct autofs_dev_ioctl *param)
 356 {
 357         int pipefd;
 358         int err = 0;
 359         struct pid *new_pid = NULL;
 360
 361         if (param->setpipefd.pipefd == -1)
 362                 return -EINVAL;
 363
 364         pipefd = param->setpipefd.pipefd;
 365
 366         mutex_lock(&sbi->wq_mutex);
 367         if (!sbi->catatonic) {
 368                 mutex_unlock(&sbi->wq_mutex);
 369                 return -EBUSY;
 370         } else {
 371                 struct file *pipe;
 372
 373                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 374
 375                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 376                         pr_warn("not allowed to change PID namespace\n");
 377                         err = -EINVAL;
 378                         goto out;
 379                 }
 380
 381                 pipe = fget(pipefd);
 382                 if (!pipe) {
 383                         err = -EBADF;
 384                         goto out;
 385                 }
 386                 if (autofs_prepare_pipe(pipe) < 0) {
 387                         err = -EPIPE;
 388                         fput(pipe);
 389                         goto out;
 390                 }
 391                 swap(sbi->oz_pgrp, new_pid);
 392                 sbi->pipefd = pipefd;
 393                 sbi->pipe = pipe;
 394                 sbi->catatonic = 0;
 395         }
 396 out:
 397         put_pid(new_pid);
 398         mutex_unlock(&sbi->wq_mutex);
 399         return err;
 400 }
 401
 402 /*
 403  * Make the autofs mount point catatonic, no longer responsive to
 404  * mount requests. Also closes the kernel pipe file descriptor.
 405  */
 406 static int autofs_dev_ioctl_catatonic(struct file *fp,
 407                                       struct autofs_sb_info *sbi,
 408                                       struct autofs_dev_ioctl *param)
 409 {
 410         autofs4_catatonic_mode(sbi);
 411         return 0;
 412 }
 413
 414 /* Set the autofs mount timeout */
 415 static int autofs_dev_ioctl_timeout(struct file *fp,
 416                                     struct autofs_sb_info *sbi,
 417                                     struct autofs_dev_ioctl *param)
 418 {
 419         unsigned long timeout;
 420
 421         timeout = param->timeout.timeout;
 422         param->timeout.timeout = sbi->exp_timeout / HZ;
 423         sbi->exp_timeout = timeout * HZ;
 424         return 0;
 425 }
 426
 427 /*
 428  * Return the uid and gid of the last request for the mount
 429  *
 430  * When reconstructing an autofs mount tree with active mounts
 431  * we need to re-connect to mounts that may have used the original
 432  * process uid and gid (or string variations of them) for mount
 433  * lookups within the map entry.
 434  */
 435 static int autofs_dev_ioctl_requester(struct file *fp,
 436                                       struct autofs_sb_info *sbi,
 437                                       struct autofs_dev_ioctl *param)
 438 {
 439         struct autofs_info *ino;
 440         struct path path;
 441         dev_t devid;
 442         int err = -ENOENT;
 443
 444         if (param->size <= sizeof(*param)) {
 445                 err = -EINVAL;
 446                 goto out;
 447         }
 448
 449         devid = sbi->sb->s_dev;
 450
 451         param->requester.uid = param->requester.gid = -1;
 452
 453         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 454         if (err)
 455                 goto out;
 456
 457         ino = autofs4_dentry_ino(path.dentry);
 458         if (ino) {
 459                 err = 0;
 460                 autofs4_expire_wait(path.dentry, 0);
 461                 spin_lock(&sbi->fs_lock);
 462                 param->requester.uid =
 463                         from_kuid_munged(current_user_ns(), ino->uid);
 464                 param->requester.gid =
 465                         from_kgid_munged(current_user_ns(), ino->gid);
 466                 spin_unlock(&sbi->fs_lock);
 467         }
 468         path_put(&path);
 469 out:
 470         return err;
 471 }
 472
 473 /*
 474  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 475  * more that can be done.
 476  */
 477 static int autofs_dev_ioctl_expire(struct file *fp,
 478                                    struct autofs_sb_info *sbi,
 479                                    struct autofs_dev_ioctl *param)
 480 {
 481         struct vfsmount *mnt;
 482         int how;
 483
 484         how = param->expire.how;
 485         mnt = fp->f_path.mnt;
 486
 487         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 488 }
 489
 490 /* Check if autofs mount point is in use */
 491 static int autofs_dev_ioctl_askumount(struct file *fp,
 492                                       struct autofs_sb_info *sbi,
 493                                       struct autofs_dev_ioctl *param)
 494 {
 495         param->askumount.may_umount = 0;
 496         if (may_umount(fp->f_path.mnt))
 497                 param->askumount.may_umount = 1;
 498         return 0;
 499 }
 500
 501 /*
 502  * Check if the given path is a mountpoint.
 503  *
 504  * If we are supplied with the file descriptor of an autofs
 505  * mount we're looking for a specific mount. In this case
 506  * the path is considered a mountpoint if it is itself a
 507  * mountpoint or contains a mount, such as a multi-mount
 508  * without a root mount. In this case we return 1 if the
 509  * path is a mount point and the super magic of the covering
 510  * mount if there is one or 0 if it isn't a mountpoint.
 511  *
 512  * If we aren't supplied with a file descriptor then we
 513  * lookup the path and check if it is the root of a mount.
 514  * If a type is given we are looking for a particular autofs
 515  * mount and if we don't find a match we return fail. If the
 516  * located path is the root of a mount we return 1 along with
 517  * the super magic of the mount or 0 otherwise.
 518  *
 519  * In both cases the the device number (as returned by
 520  * new_encode_dev()) is also returned.
 521  */
 522 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 523                                          struct autofs_sb_info *sbi,
 524                                          struct autofs_dev_ioctl *param)
 525 {
 526         struct path path;
 527         const char *name;
 528         unsigned int type;
 529         unsigned int devid, magic;
 530         int err = -ENOENT;
 531
 532         if (param->size <= sizeof(*param)) {
 533                 err = -EINVAL;
 534                 goto out;
 535         }
 536
 537         name = param->path;
 538         type = param->ismountpoint.in.type;
 539
 540         param->ismountpoint.out.devid = devid = 0;
 541         param->ismountpoint.out.magic = magic = 0;
 542
 543         if (!fp || param->ioctlfd == -1) {
 544                 if (autofs_type_any(type))
 545                         err = kern_path_mountpoint(AT_FDCWD,
 546                                                    name, &path, LOOKUP_FOLLOW);
 547                 else
 548                         err = find_autofs_mount(name, &path,
 549                                                 test_by_type, &type);
 550                 if (err)
 551                         goto out;
 552                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 553                 err = 0;
 554                 if (path.mnt->mnt_root == path.dentry) {
 555                         err = 1;
 556                         magic = path.dentry->d_sb->s_magic;
 557                 }
 558         } else {
 559                 dev_t dev = sbi->sb->s_dev;
 560
 561                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 562                 if (err)
 563                         goto out;
 564
 565                 devid = new_encode_dev(dev);
 566
 567                 err = have_submounts(path.dentry);
 568
 569                 if (follow_down_one(&path))
 570                         magic = path.dentry->d_sb->s_magic;
 571         }
 572
 573         param->ismountpoint.out.devid = devid;
 574         param->ismountpoint.out.magic = magic;
 575         path_put(&path);
 576 out:
 577         return err;
 578 }
 579
 580 /*
 581  * Our range of ioctl numbers isn't 0 based so we need to shift
 582  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 583  * lookup.
 584  */
 585 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 586
 587 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 588 {
 589         static struct {
 590                 int cmd;
 591                 ioctl_fn fn;
 592         } _ioctls[] = {
 593                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 594                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 595                          autofs_dev_ioctl_protover},
 596                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 597                          autofs_dev_ioctl_protosubver},
 598                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 599                          autofs_dev_ioctl_openmount},
 600                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 601                          autofs_dev_ioctl_closemount},
 602                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 603                          autofs_dev_ioctl_ready},
 604                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 605                          autofs_dev_ioctl_fail},
 606                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 607                          autofs_dev_ioctl_setpipefd},
 608                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 609                          autofs_dev_ioctl_catatonic},
 610                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 611                          autofs_dev_ioctl_timeout},
 612                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 613                          autofs_dev_ioctl_requester},
 614                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 615                          autofs_dev_ioctl_expire},
 616                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 617                          autofs_dev_ioctl_askumount},
 618                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 619                          autofs_dev_ioctl_ismountpoint}
 620         };
 621         unsigned int idx = cmd_idx(cmd);
 622
 623         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 624 }
 625
 626 /* ioctl dispatcher */
 627 static int _autofs_dev_ioctl(unsigned int command,
 628                              struct autofs_dev_ioctl __user *user)
 629 {
 630         struct autofs_dev_ioctl *param;
 631         struct file *fp;
 632         struct autofs_sb_info *sbi;
 633         unsigned int cmd_first, cmd;
 634         ioctl_fn fn = NULL;
 635         int err = 0;
 636
 637         /* only root can play with this */
 638         if (!capable(CAP_SYS_ADMIN))
 639                 return -EPERM;
 640
 641         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 642         cmd = _IOC_NR(command);
 643
 644         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 645             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 646                 return -ENOTTY;
 647         }
 648
 649         /* Copy the parameters into kernel space. */
 650         param = copy_dev_ioctl(user);
 651         if (IS_ERR(param))
 652                 return PTR_ERR(param);
 653
 654         err = validate_dev_ioctl(command, param);
 655         if (err)
 656                 goto out;
 657
 658         /* The validate routine above always sets the version */
 659         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 660                 goto done;
 661
 662         fn = lookup_dev_ioctl(cmd);
 663         if (!fn) {
 664                 pr_warn("unknown command 0x%08x\n", command);
 665                 return -ENOTTY;
 666         }
 667
 668         fp = NULL;
 669         sbi = NULL;
 670
 671         /*
 672          * For obvious reasons the openmount can't have a file
 673          * descriptor yet. We don't take a reference to the
 674          * file during close to allow for immediate release.
 675          */
 676         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 677             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 678                 fp = fget(param->ioctlfd);
 679                 if (!fp) {
 680                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 681                                 goto cont;
 682                         err = -EBADF;
 683                         goto out;
 684                 }
 685
 686                 sbi = autofs_dev_ioctl_sbi(fp);
 687                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 688                         err = -EINVAL;
 689                         fput(fp);
 690                         goto out;
 691                 }
 692
 693                 /*
 694                  * Admin needs to be able to set the mount catatonic in
 695                  * order to be able to perform the re-open.
 696                  */
 697                 if (!autofs4_oz_mode(sbi) &&
 698                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 699                         err = -EACCES;
 700                         fput(fp);
 701                         goto out;
 702                 }
 703         }
 704 cont:
 705         err = fn(fp, sbi, param);
 706
 707         if (fp)
 708                 fput(fp);
 709 done:
 710         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 711                 err = -EFAULT;
 712 out:
 713         free_dev_ioctl(param);
 714         return err;
 715 }
 716
 717 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 718 {
 719         int err;
 720
 721         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 722         return (long) err;
 723 }
 724
 725 #ifdef CONFIG_COMPAT
 726 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 727 {
 728         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 729 }
 730 #else
 731 #define autofs_dev_ioctl_compat NULL
 732 #endif
 733
 734 static const struct file_operations _dev_ioctl_fops = {
 735         .unlocked_ioctl  = autofs_dev_ioctl,
 736         .compat_ioctl = autofs_dev_ioctl_compat,
 737         .owner   = THIS_MODULE,
 738         .llseek = noop_llseek,
 739 };
 740
 741 static struct miscdevice _autofs_dev_ioctl_misc = {
 742         .minor          = AUTOFS_MINOR,
 743         .name           = AUTOFS_DEVICE_NAME,
 744         .fops           = &_dev_ioctl_fops
 745 };
 746
 747 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 748 MODULE_ALIAS("devname:autofs");
 749
 750 /* Register/deregister misc character device */
 751 int __init autofs_dev_ioctl_init(void)
 752 {
 753         int r;
 754
 755         r = misc_register(&_autofs_dev_ioctl_misc);
 756         if (r) {
 757                 pr_err("misc_register failed for control device\n");
 758                 return r;
 759         }
 760
 761         return 0;
 762 }
 763
 764 void autofs_dev_ioctl_exit(void)
 765 {
 766         misc_deregister(&_autofs_dev_ioctl_misc);
 767 }