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 = f->f_path.dentry->d_inode;
 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 static int find_autofs_mount(const char *pathname,
 187                              struct path *res,
 188                              int test(struct path *path, void *data),
 189                              void *data)
 190 {
 191         struct path path;
 192         int err = kern_path(pathname, 0, &path);
 193         if (err)
 194                 return err;
 195         err = -ENOENT;
 196         while (path.dentry == path.mnt->mnt_root) {
 197                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 198                         if (test(&path, data)) {
 199                                 path_get(&path);
 200                                 if (!err) /* already found some */
 201                                         path_put(res);
 202                                 *res = path;
 203                                 err = 0;
 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 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
 225 {
 226         struct files_struct *files = current->files;
 227         struct fdtable *fdt;
 228
 229         spin_lock(&files->file_lock);
 230         fdt = files_fdtable(files);
 231         BUG_ON(fdt->fd[fd] != NULL);
 232         rcu_assign_pointer(fdt->fd[fd], file);
 233         FD_SET(fd, fdt->close_on_exec);
 234         spin_unlock(&files->file_lock);
 235 }
 236
 237
 238 /*
 239  * Open a file descriptor on the autofs mount point corresponding
 240  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 241  */
 242 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 243 {
 244         int err, fd;
 245
 246         fd = get_unused_fd();
 247         if (likely(fd >= 0)) {
 248                 struct file *filp;
 249                 struct path path;
 250
 251                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 252                 if (err)
 253                         goto out;
 254
 255                 /*
 256                  * Find autofs super block that has the device number
 257                  * corresponding to the autofs fs we want to open.
 258                  */
 259
 260                 filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
 261                                    current_cred());
 262                 if (IS_ERR(filp)) {
 263                         err = PTR_ERR(filp);
 264                         goto out;
 265                 }
 266
 267                 autofs_dev_ioctl_fd_install(fd, filp);
 268         }
 269
 270         return fd;
 271
 272 out:
 273         put_unused_fd(fd);
 274         return err;
 275 }
 276
 277 /* Open a file descriptor on an autofs mount point */
 278 static int autofs_dev_ioctl_openmount(struct file *fp,
 279                                       struct autofs_sb_info *sbi,
 280                                       struct autofs_dev_ioctl *param)
 281 {
 282         const char *path;
 283         dev_t devid;
 284         int err, fd;
 285
 286         /* param->path has already been checked */
 287         if (!param->openmount.devid)
 288                 return -EINVAL;
 289
 290         param->ioctlfd = -1;
 291
 292         path = param->path;
 293         devid = new_decode_dev(param->openmount.devid);
 294
 295         err = 0;
 296         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 297         if (unlikely(fd < 0)) {
 298                 err = fd;
 299                 goto out;
 300         }
 301
 302         param->ioctlfd = fd;
 303 out:
 304         return err;
 305 }
 306
 307 /* Close file descriptor allocated above (user can also use close(2)). */
 308 static int autofs_dev_ioctl_closemount(struct file *fp,
 309                                        struct autofs_sb_info *sbi,
 310                                        struct autofs_dev_ioctl *param)
 311 {
 312         return sys_close(param->ioctlfd);
 313 }
 314
 315 /*
 316  * Send "ready" status for an existing wait (either a mount or an expire
 317  * request).
 318  */
 319 static int autofs_dev_ioctl_ready(struct file *fp,
 320                                   struct autofs_sb_info *sbi,
 321                                   struct autofs_dev_ioctl *param)
 322 {
 323         autofs_wqt_t token;
 324
 325         token = (autofs_wqt_t) param->ready.token;
 326         return autofs4_wait_release(sbi, token, 0);
 327 }
 328
 329 /*
 330  * Send "fail" status for an existing wait (either a mount or an expire
 331  * request).
 332  */
 333 static int autofs_dev_ioctl_fail(struct file *fp,
 334                                  struct autofs_sb_info *sbi,
 335                                  struct autofs_dev_ioctl *param)
 336 {
 337         autofs_wqt_t token;
 338         int status;
 339
 340         token = (autofs_wqt_t) param->fail.token;
 341         status = param->fail.status ? param->fail.status : -ENOENT;
 342         return autofs4_wait_release(sbi, token, status);
 343 }
 344
 345 /*
 346  * Set the pipe fd for kernel communication to the daemon.
 347  *
 348  * Normally this is set at mount using an option but if we
 349  * are reconnecting to a busy mount then we need to use this
 350  * to tell the autofs mount about the new kernel pipe fd. In
 351  * order to protect mounts against incorrectly setting the
 352  * pipefd we also require that the autofs mount be catatonic.
 353  *
 354  * This also sets the process group id used to identify the
 355  * controlling process (eg. the owning automount(8) daemon).
 356  */
 357 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 358                                       struct autofs_sb_info *sbi,
 359                                       struct autofs_dev_ioctl *param)
 360 {
 361         int pipefd;
 362         int err = 0;
 363
 364         if (param->setpipefd.pipefd == -1)
 365                 return -EINVAL;
 366
 367         pipefd = param->setpipefd.pipefd;
 368
 369         mutex_lock(&sbi->wq_mutex);
 370         if (!sbi->catatonic) {
 371                 mutex_unlock(&sbi->wq_mutex);
 372                 return -EBUSY;
 373         } else {
 374                 struct file *pipe = fget(pipefd);
 375                 if (!pipe) {
 376                         err = -EBADF;
 377                         goto out;
 378                 }
 379                 if (!pipe->f_op || !pipe->f_op->write) {
 380                         err = -EPIPE;
 381                         fput(pipe);
 382                         goto out;
 383                 }
 384                 sbi->oz_pgrp = task_pgrp_nr(current);
 385                 sbi->pipefd = pipefd;
 386                 sbi->pipe = pipe;
 387                 sbi->catatonic = 0;
 388         }
 389 out:
 390         mutex_unlock(&sbi->wq_mutex);
 391         return err;
 392 }
 393
 394 /*
 395  * Make the autofs mount point catatonic, no longer responsive to
 396  * mount requests. Also closes the kernel pipe file descriptor.
 397  */
 398 static int autofs_dev_ioctl_catatonic(struct file *fp,
 399                                       struct autofs_sb_info *sbi,
 400                                       struct autofs_dev_ioctl *param)
 401 {
 402         autofs4_catatonic_mode(sbi);
 403         return 0;
 404 }
 405
 406 /* Set the autofs mount timeout */
 407 static int autofs_dev_ioctl_timeout(struct file *fp,
 408                                     struct autofs_sb_info *sbi,
 409                                     struct autofs_dev_ioctl *param)
 410 {
 411         unsigned long timeout;
 412
 413         timeout = param->timeout.timeout;
 414         param->timeout.timeout = sbi->exp_timeout / HZ;
 415         sbi->exp_timeout = timeout * HZ;
 416         return 0;
 417 }
 418
 419 /*
 420  * Return the uid and gid of the last request for the mount
 421  *
 422  * When reconstructing an autofs mount tree with active mounts
 423  * we need to re-connect to mounts that may have used the original
 424  * process uid and gid (or string variations of them) for mount
 425  * lookups within the map entry.
 426  */
 427 static int autofs_dev_ioctl_requester(struct file *fp,
 428                                       struct autofs_sb_info *sbi,
 429                                       struct autofs_dev_ioctl *param)
 430 {
 431         struct autofs_info *ino;
 432         struct path path;
 433         dev_t devid;
 434         int err = -ENOENT;
 435
 436         if (param->size <= sizeof(*param)) {
 437                 err = -EINVAL;
 438                 goto out;
 439         }
 440
 441         devid = sbi->sb->s_dev;
 442
 443         param->requester.uid = param->requester.gid = -1;
 444
 445         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 446         if (err)
 447                 goto out;
 448
 449         ino = autofs4_dentry_ino(path.dentry);
 450         if (ino) {
 451                 err = 0;
 452                 autofs4_expire_wait(path.dentry);
 453                 spin_lock(&sbi->fs_lock);
 454                 param->requester.uid = ino->uid;
 455                 param->requester.gid = ino->gid;
 456                 spin_unlock(&sbi->fs_lock);
 457         }
 458         path_put(&path);
 459 out:
 460         return err;
 461 }
 462
 463 /*
 464  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 465  * more that can be done.
 466  */
 467 static int autofs_dev_ioctl_expire(struct file *fp,
 468                                    struct autofs_sb_info *sbi,
 469                                    struct autofs_dev_ioctl *param)
 470 {
 471         struct vfsmount *mnt;
 472         int how;
 473
 474         how = param->expire.how;
 475         mnt = fp->f_path.mnt;
 476
 477         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 478 }
 479
 480 /* Check if autofs mount point is in use */
 481 static int autofs_dev_ioctl_askumount(struct file *fp,
 482                                       struct autofs_sb_info *sbi,
 483                                       struct autofs_dev_ioctl *param)
 484 {
 485         param->askumount.may_umount = 0;
 486         if (may_umount(fp->f_path.mnt))
 487                 param->askumount.may_umount = 1;
 488         return 0;
 489 }
 490
 491 /*
 492  * Check if the given path is a mountpoint.
 493  *
 494  * If we are supplied with the file descriptor of an autofs
 495  * mount we're looking for a specific mount. In this case
 496  * the path is considered a mountpoint if it is itself a
 497  * mountpoint or contains a mount, such as a multi-mount
 498  * without a root mount. In this case we return 1 if the
 499  * path is a mount point and the super magic of the covering
 500  * mount if there is one or 0 if it isn't a mountpoint.
 501  *
 502  * If we aren't supplied with a file descriptor then we
 503  * lookup the nameidata of the path and check if it is the
 504  * root of a mount. If a type is given we are looking for
 505  * a particular autofs mount and if we don't find a match
 506  * we return fail. If the located nameidata path is the
 507  * root of a mount we return 1 along with the super magic
 508  * 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(name, LOOKUP_FOLLOW, &path);
 537                 else
 538                         err = find_autofs_mount(name, &path, test_by_type, &type);
 539                 if (err)
 540                         goto out;
 541                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 542                 err = 0;
 543                 if (path.mnt->mnt_root == path.dentry) {
 544                         err = 1;
 545                         magic = path.dentry->d_sb->s_magic;
 546                 }
 547         } else {
 548                 dev_t dev = sbi->sb->s_dev;
 549
 550                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 551                 if (err)
 552                         goto out;
 553
 554                 devid = new_encode_dev(dev);
 555
 556                 err = have_submounts(path.dentry);
 557
 558                 if (follow_down_one(&path))
 559                         magic = path.dentry->d_sb->s_magic;
 560         }
 561
 562         param->ismountpoint.out.devid = devid;
 563         param->ismountpoint.out.magic = magic;
 564         path_put(&path);
 565 out:
 566         return err;
 567 }
 568
 569 /*
 570  * Our range of ioctl numbers isn't 0 based so we need to shift
 571  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 572  * lookup.
 573  */
 574 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 575
 576 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 577 {
 578         static struct {
 579                 int cmd;
 580                 ioctl_fn fn;
 581         } _ioctls[] = {
 582                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 583                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 584                          autofs_dev_ioctl_protover},
 585                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 586                          autofs_dev_ioctl_protosubver},
 587                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 588                          autofs_dev_ioctl_openmount},
 589                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 590                          autofs_dev_ioctl_closemount},
 591                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 592                          autofs_dev_ioctl_ready},
 593                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 594                          autofs_dev_ioctl_fail},
 595                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 596                          autofs_dev_ioctl_setpipefd},
 597                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 598                          autofs_dev_ioctl_catatonic},
 599                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 600                          autofs_dev_ioctl_timeout},
 601                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 602                          autofs_dev_ioctl_requester},
 603                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 604                          autofs_dev_ioctl_expire},
 605                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 606                          autofs_dev_ioctl_askumount},
 607                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 608                          autofs_dev_ioctl_ismountpoint}
 609         };
 610         unsigned int idx = cmd_idx(cmd);
 611
 612         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 613 }
 614
 615 /* ioctl dispatcher */
 616 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 617 {
 618         struct autofs_dev_ioctl *param;
 619         struct file *fp;
 620         struct autofs_sb_info *sbi;
 621         unsigned int cmd_first, cmd;
 622         ioctl_fn fn = NULL;
 623         int err = 0;
 624
 625         /* only root can play with this */
 626         if (!capable(CAP_SYS_ADMIN))
 627                 return -EPERM;
 628
 629         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 630         cmd = _IOC_NR(command);
 631
 632         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 633             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 634                 return -ENOTTY;
 635         }
 636
 637         /* Copy the parameters into kernel space. */
 638         param = copy_dev_ioctl(user);
 639         if (IS_ERR(param))
 640                 return PTR_ERR(param);
 641
 642         err = validate_dev_ioctl(command, param);
 643         if (err)
 644                 goto out;
 645
 646         /* The validate routine above always sets the version */
 647         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 648                 goto done;
 649
 650         fn = lookup_dev_ioctl(cmd);
 651         if (!fn) {
 652                 AUTOFS_WARN("unknown command 0x%08x", command);
 653                 return -ENOTTY;
 654         }
 655
 656         fp = NULL;
 657         sbi = NULL;
 658
 659         /*
 660          * For obvious reasons the openmount can't have a file
 661          * descriptor yet. We don't take a reference to the
 662          * file during close to allow for immediate release.
 663          */
 664         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 665             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 666                 fp = fget(param->ioctlfd);
 667                 if (!fp) {
 668                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 669                                 goto cont;
 670                         err = -EBADF;
 671                         goto out;
 672                 }
 673
 674                 if (!fp->f_op) {
 675                         err = -ENOTTY;
 676                         fput(fp);
 677                         goto out;
 678                 }
 679
 680                 sbi = autofs_dev_ioctl_sbi(fp);
 681                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 682                         err = -EINVAL;
 683                         fput(fp);
 684                         goto out;
 685                 }
 686
 687                 /*
 688                  * Admin needs to be able to set the mount catatonic in
 689                  * order to be able to perform the re-open.
 690                  */
 691                 if (!autofs4_oz_mode(sbi) &&
 692                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 693                         err = -EACCES;
 694                         fput(fp);
 695                         goto out;
 696                 }
 697         }
 698 cont:
 699         err = fn(fp, sbi, param);
 700
 701         if (fp)
 702                 fput(fp);
 703 done:
 704         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 705                 err = -EFAULT;
 706 out:
 707         free_dev_ioctl(param);
 708         return err;
 709 }
 710
 711 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 712 {
 713         int err;
 714         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 715         return (long) err;
 716 }
 717
 718 #ifdef CONFIG_COMPAT
 719 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 720 {
 721         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 722 }
 723 #else
 724 #define autofs_dev_ioctl_compat NULL
 725 #endif
 726
 727 static const struct file_operations _dev_ioctl_fops = {
 728         .unlocked_ioctl  = autofs_dev_ioctl,
 729         .compat_ioctl = autofs_dev_ioctl_compat,
 730         .owner   = THIS_MODULE,
 731         .llseek = noop_llseek,
 732 };
 733
 734 static struct miscdevice _autofs_dev_ioctl_misc = {
 735         .minor          = AUTOFS_MINOR,
 736         .name           = AUTOFS_DEVICE_NAME,
 737         .fops           = &_dev_ioctl_fops
 738 };
 739
 740 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 741 MODULE_ALIAS("devname:autofs");
 742
 743 /* Register/deregister misc character device */
 744 int autofs_dev_ioctl_init(void)
 745 {
 746         int r;
 747
 748         r = misc_register(&_autofs_dev_ioctl_misc);
 749         if (r) {
 750                 AUTOFS_ERROR("misc_register failed for control device");
 751                 return r;
 752         }
 753
 754         return 0;
 755 }
 756
 757 void autofs_dev_ioctl_exit(void)
 758 {
 759         misc_deregister(&_autofs_dev_ioctl_misc);
 760         return;
 761 }
 762