fs/autofs4/dev-ioctl.c

   1 /*
   2  * Copyright 2008 Red Hat, Inc. All rights reserved.
   3  * Copyright 2008 Ian Kent <raven@themaw.net>
   4  *
   5  * This file is part of the Linux kernel and is made available under
   6  * the terms of the GNU General Public License, version 2, or at your
   7  * option, any later version, incorporated herein by reference.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/vmalloc.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/init.h>
  14 #include <linux/wait.h>
  15 #include <linux/namei.h>
  16 #include <linux/fcntl.h>
  17 #include <linux/file.h>
  18 #include <linux/fdtable.h>
  19 #include <linux/sched.h>
  20 #include <linux/cred.h>
  21 #include <linux/compat.h>
  22 #include <linux/syscalls.h>
  23 #include <linux/magic.h>
  24 #include <linux/dcache.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/slab.h>
  27
  28 #include "autofs_i.h"
  29
  30 /*
  31  * This module implements an interface for routing autofs ioctl control
  32  * commands via a miscellaneous device file.
  33  *
  34  * The alternate interface is needed because we need to be able open
  35  * an ioctl file descriptor on an autofs mount that may be covered by
  36  * another mount. This situation arises when starting automount(8)
  37  * or other user space daemon which uses direct mounts or offset
  38  * mounts (used for autofs lazy mount/umount of nested mount trees),
  39  * which have been left busy at at service shutdown.
  40  */
  41
  42 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
  43                         struct autofs_dev_ioctl *);
  44
  45 static int check_name(const char *name)
  46 {
  47         if (!strchr(name, '/'))
  48                 return -EINVAL;
  49         return 0;
  50 }
  51
  52 /*
  53  * Check a string doesn't overrun the chunk of
  54  * memory we copied from user land.
  55  */
  56 static int invalid_str(char *str, size_t size)
  57 {
  58         if (memchr(str, 0, size))
  59                 return 0;
  60         return -EINVAL;
  61 }
  62
  63 /*
  64  * Check that the user compiled against correct version of autofs
  65  * misc device code.
  66  *
  67  * As well as checking the version compatibility this always copies
  68  * the kernel interface version out.
  69  */
  70 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
  71 {
  72         int err = 0;
  73
  74         if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
  75             (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
  76                 pr_warn("ioctl control interface version mismatch: "
  77                         "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
  78                         AUTOFS_DEV_IOCTL_VERSION_MAJOR,
  79                         AUTOFS_DEV_IOCTL_VERSION_MINOR,
  80                         param->ver_major, param->ver_minor, cmd);
  81                 err = -EINVAL;
  82         }
  83
  84         /* Fill in the kernel version. */
  85         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
  86         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
  87
  88         return err;
  89 }
  90
  91 /*
  92  * Copy parameter control struct, including a possible path allocated
  93  * at the end of the struct.
  94  */
  95 static struct autofs_dev_ioctl *
  96 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
  97 {
  98         struct autofs_dev_ioctl tmp, *res;
  99
 100         if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
 101                 return ERR_PTR(-EFAULT);
 102
 103         if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
 104                 return ERR_PTR(-EINVAL);
 105
 106         if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
 107                 return ERR_PTR(-ENAMETOOLONG);
 108
 109         res = memdup_user(in, tmp.size);
 110         if (!IS_ERR(res))
 111                 res->size = tmp.size;
 112
 113         return res;
 114 }
 115
 116 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 117 {
 118         kfree(param);
 119 }
 120
 121 /*
 122  * Check sanity of parameter control fields and if a path is present
 123  * check that it is terminated and contains at least one "/".
 124  */
 125 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 126 {
 127         int err;
 128
 129         err = check_dev_ioctl_version(cmd, param);
 130         if (err) {
 131                 pr_warn("invalid device control module version "
 132                         "supplied for cmd(0x%08x)\n", cmd);
 133                 goto out;
 134         }
 135
 136         if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
 137                 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
 138                 if (err) {
 139                         pr_warn(
 140                           "path string terminator missing for cmd(0x%08x)\n",
 141                           cmd);
 142                         goto out;
 143                 }
 144
 145                 err = check_name(param->path);
 146                 if (err) {
 147                         pr_warn("invalid path supplied for cmd(0x%08x)\n",
 148                                 cmd);
 149                         goto out;
 150                 }
 151         } else {
 152                 unsigned int inr = _IOC_NR(cmd);
 153
 154                 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
 155                     inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
 156                     inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
 157                         err = -EINVAL;
 158                         goto out;
 159                 }
 160         }
 161
 162         err = 0;
 163 out:
 164         return err;
 165 }
 166
 167 /*
 168  * Get the autofs super block info struct from the file opened on
 169  * the autofs mount point.
 170  */
 171 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 172 {
 173         struct autofs_sb_info *sbi = NULL;
 174         struct inode *inode;
 175
 176         if (f) {
 177                 inode = file_inode(f);
 178                 sbi = autofs4_sbi(inode->i_sb);
 179         }
 180         return sbi;
 181 }
 182
 183 /* Return autofs dev ioctl version */
 184 static int autofs_dev_ioctl_version(struct file *fp,
 185                                     struct autofs_sb_info *sbi,
 186                                     struct autofs_dev_ioctl *param)
 187 {
 188         /* This should have already been set. */
 189         param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
 190         param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
 191         return 0;
 192 }
 193
 194 /* Return autofs module protocol version */
 195 static int autofs_dev_ioctl_protover(struct file *fp,
 196                                      struct autofs_sb_info *sbi,
 197                                      struct autofs_dev_ioctl *param)
 198 {
 199         param->protover.version = sbi->version;
 200         return 0;
 201 }
 202
 203 /* Return autofs module protocol sub version */
 204 static int autofs_dev_ioctl_protosubver(struct file *fp,
 205                                         struct autofs_sb_info *sbi,
 206                                         struct autofs_dev_ioctl *param)
 207 {
 208         param->protosubver.sub_version = sbi->sub_version;
 209         return 0;
 210 }
 211
 212 /* Find the topmost mount satisfying test() */
 213 static int find_autofs_mount(const char *pathname,
 214                              struct path *res,
 215                              int test(const struct path *path, void *data),
 216                              void *data)
 217 {
 218         struct path path;
 219         int err;
 220
 221         err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
 222         if (err)
 223                 return err;
 224         err = -ENOENT;
 225         while (path.dentry == path.mnt->mnt_root) {
 226                 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
 227                         if (test(&path, data)) {
 228                                 path_get(&path);
 229                                 *res = path;
 230                                 err = 0;
 231                                 break;
 232                         }
 233                 }
 234                 if (!follow_up(&path))
 235                         break;
 236         }
 237         path_put(&path);
 238         return err;
 239 }
 240
 241 static int test_by_dev(const struct path *path, void *p)
 242 {
 243         return path->dentry->d_sb->s_dev == *(dev_t *)p;
 244 }
 245
 246 static int test_by_type(const struct path *path, void *p)
 247 {
 248         struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
 249
 250         return ino && ino->sbi->type & *(unsigned *)p;
 251 }
 252
 253 /*
 254  * Open a file descriptor on the autofs mount point corresponding
 255  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 256  */
 257 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 258 {
 259         int err, fd;
 260
 261         fd = get_unused_fd_flags(O_CLOEXEC);
 262         if (likely(fd >= 0)) {
 263                 struct file *filp;
 264                 struct path path;
 265
 266                 err = find_autofs_mount(name, &path, test_by_dev, &devid);
 267                 if (err)
 268                         goto out;
 269
 270                 filp = dentry_open(&path, O_RDONLY, current_cred());
 271                 path_put(&path);
 272                 if (IS_ERR(filp)) {
 273                         err = PTR_ERR(filp);
 274                         goto out;
 275                 }
 276
 277                 fd_install(fd, filp);
 278         }
 279
 280         return fd;
 281
 282 out:
 283         put_unused_fd(fd);
 284         return err;
 285 }
 286
 287 /* Open a file descriptor on an autofs mount point */
 288 static int autofs_dev_ioctl_openmount(struct file *fp,
 289                                       struct autofs_sb_info *sbi,
 290                                       struct autofs_dev_ioctl *param)
 291 {
 292         const char *path;
 293         dev_t devid;
 294         int err, fd;
 295
 296         /* param->path has been checked in validate_dev_ioctl() */
 297
 298         if (!param->openmount.devid)
 299                 return -EINVAL;
 300
 301         param->ioctlfd = -1;
 302
 303         path = param->path;
 304         devid = new_decode_dev(param->openmount.devid);
 305
 306         err = 0;
 307         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 308         if (unlikely(fd < 0)) {
 309                 err = fd;
 310                 goto out;
 311         }
 312
 313         param->ioctlfd = fd;
 314 out:
 315         return err;
 316 }
 317
 318 /* Close file descriptor allocated above (user can also use close(2)). */
 319 static int autofs_dev_ioctl_closemount(struct file *fp,
 320                                        struct autofs_sb_info *sbi,
 321                                        struct autofs_dev_ioctl *param)
 322 {
 323         return sys_close(param->ioctlfd);
 324 }
 325
 326 /*
 327  * Send "ready" status for an existing wait (either a mount or an expire
 328  * request).
 329  */
 330 static int autofs_dev_ioctl_ready(struct file *fp,
 331                                   struct autofs_sb_info *sbi,
 332                                   struct autofs_dev_ioctl *param)
 333 {
 334         autofs_wqt_t token;
 335
 336         token = (autofs_wqt_t) param->ready.token;
 337         return autofs4_wait_release(sbi, token, 0);
 338 }
 339
 340 /*
 341  * Send "fail" status for an existing wait (either a mount or an expire
 342  * request).
 343  */
 344 static int autofs_dev_ioctl_fail(struct file *fp,
 345                                  struct autofs_sb_info *sbi,
 346                                  struct autofs_dev_ioctl *param)
 347 {
 348         autofs_wqt_t token;
 349         int status;
 350
 351         token = (autofs_wqt_t) param->fail.token;
 352         status = param->fail.status < 0 ? param->fail.status : -ENOENT;
 353         return autofs4_wait_release(sbi, token, status);
 354 }
 355
 356 /*
 357  * Set the pipe fd for kernel communication to the daemon.
 358  *
 359  * Normally this is set at mount using an option but if we
 360  * are reconnecting to a busy mount then we need to use this
 361  * to tell the autofs mount about the new kernel pipe fd. In
 362  * order to protect mounts against incorrectly setting the
 363  * pipefd we also require that the autofs mount be catatonic.
 364  *
 365  * This also sets the process group id used to identify the
 366  * controlling process (eg. the owning automount(8) daemon).
 367  */
 368 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 369                                       struct autofs_sb_info *sbi,
 370                                       struct autofs_dev_ioctl *param)
 371 {
 372         int pipefd;
 373         int err = 0;
 374         struct pid *new_pid = NULL;
 375
 376         if (param->setpipefd.pipefd == -1)
 377                 return -EINVAL;
 378
 379         pipefd = param->setpipefd.pipefd;
 380
 381         mutex_lock(&sbi->wq_mutex);
 382         if (!sbi->catatonic) {
 383                 mutex_unlock(&sbi->wq_mutex);
 384                 return -EBUSY;
 385         } else {
 386                 struct file *pipe;
 387
 388                 new_pid = get_task_pid(current, PIDTYPE_PGID);
 389
 390                 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
 391                         pr_warn("not allowed to change PID namespace\n");
 392                         err = -EINVAL;
 393                         goto out;
 394                 }
 395
 396                 pipe = fget(pipefd);
 397                 if (!pipe) {
 398                         err = -EBADF;
 399                         goto out;
 400                 }
 401                 if (autofs_prepare_pipe(pipe) < 0) {
 402                         err = -EPIPE;
 403                         fput(pipe);
 404                         goto out;
 405                 }
 406                 swap(sbi->oz_pgrp, new_pid);
 407                 sbi->pipefd = pipefd;
 408                 sbi->pipe = pipe;
 409                 sbi->catatonic = 0;
 410         }
 411 out:
 412         put_pid(new_pid);
 413         mutex_unlock(&sbi->wq_mutex);
 414         return err;
 415 }
 416
 417 /*
 418  * Make the autofs mount point catatonic, no longer responsive to
 419  * mount requests. Also closes the kernel pipe file descriptor.
 420  */
 421 static int autofs_dev_ioctl_catatonic(struct file *fp,
 422                                       struct autofs_sb_info *sbi,
 423                                       struct autofs_dev_ioctl *param)
 424 {
 425         autofs4_catatonic_mode(sbi);
 426         return 0;
 427 }
 428
 429 /* Set the autofs mount timeout */
 430 static int autofs_dev_ioctl_timeout(struct file *fp,
 431                                     struct autofs_sb_info *sbi,
 432                                     struct autofs_dev_ioctl *param)
 433 {
 434         unsigned long timeout;
 435
 436         timeout = param->timeout.timeout;
 437         param->timeout.timeout = sbi->exp_timeout / HZ;
 438         sbi->exp_timeout = timeout * HZ;
 439         return 0;
 440 }
 441
 442 /*
 443  * Return the uid and gid of the last request for the mount
 444  *
 445  * When reconstructing an autofs mount tree with active mounts
 446  * we need to re-connect to mounts that may have used the original
 447  * process uid and gid (or string variations of them) for mount
 448  * lookups within the map entry.
 449  */
 450 static int autofs_dev_ioctl_requester(struct file *fp,
 451                                       struct autofs_sb_info *sbi,
 452                                       struct autofs_dev_ioctl *param)
 453 {
 454         struct autofs_info *ino;
 455         struct path path;
 456         dev_t devid;
 457         int err = -ENOENT;
 458
 459         /* param->path has been checked in validate_dev_ioctl() */
 460
 461         devid = sbi->sb->s_dev;
 462
 463         param->requester.uid = param->requester.gid = -1;
 464
 465         err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
 466         if (err)
 467                 goto out;
 468
 469         ino = autofs4_dentry_ino(path.dentry);
 470         if (ino) {
 471                 err = 0;
 472                 autofs4_expire_wait(&path, 0);
 473                 spin_lock(&sbi->fs_lock);
 474                 param->requester.uid =
 475                         from_kuid_munged(current_user_ns(), ino->uid);
 476                 param->requester.gid =
 477                         from_kgid_munged(current_user_ns(), ino->gid);
 478                 spin_unlock(&sbi->fs_lock);
 479         }
 480         path_put(&path);
 481 out:
 482         return err;
 483 }
 484
 485 /*
 486  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 487  * more that can be done.
 488  */
 489 static int autofs_dev_ioctl_expire(struct file *fp,
 490                                    struct autofs_sb_info *sbi,
 491                                    struct autofs_dev_ioctl *param)
 492 {
 493         struct vfsmount *mnt;
 494         int how;
 495
 496         how = param->expire.how;
 497         mnt = fp->f_path.mnt;
 498
 499         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 500 }
 501
 502 /* Check if autofs mount point is in use */
 503 static int autofs_dev_ioctl_askumount(struct file *fp,
 504                                       struct autofs_sb_info *sbi,
 505                                       struct autofs_dev_ioctl *param)
 506 {
 507         param->askumount.may_umount = 0;
 508         if (may_umount(fp->f_path.mnt))
 509                 param->askumount.may_umount = 1;
 510         return 0;
 511 }
 512
 513 /*
 514  * Check if the given path is a mountpoint.
 515  *
 516  * If we are supplied with the file descriptor of an autofs
 517  * mount we're looking for a specific mount. In this case
 518  * the path is considered a mountpoint if it is itself a
 519  * mountpoint or contains a mount, such as a multi-mount
 520  * without a root mount. In this case we return 1 if the
 521  * path is a mount point and the super magic of the covering
 522  * mount if there is one or 0 if it isn't a mountpoint.
 523  *
 524  * If we aren't supplied with a file descriptor then we
 525  * lookup the path and check if it is the root of a mount.
 526  * If a type is given we are looking for a particular autofs
 527  * mount and if we don't find a match we return fail. If the
 528  * located path is the root of a mount we return 1 along with
 529  * the super magic of the mount or 0 otherwise.
 530  *
 531  * In both cases the the device number (as returned by
 532  * new_encode_dev()) is also returned.
 533  */
 534 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 535                                          struct autofs_sb_info *sbi,
 536                                          struct autofs_dev_ioctl *param)
 537 {
 538         struct path path;
 539         const char *name;
 540         unsigned int type;
 541         unsigned int devid, magic;
 542         int err = -ENOENT;
 543
 544         /* param->path has been checked in validate_dev_ioctl() */
 545
 546         name = param->path;
 547         type = param->ismountpoint.in.type;
 548
 549         param->ismountpoint.out.devid = devid = 0;
 550         param->ismountpoint.out.magic = magic = 0;
 551
 552         if (!fp || param->ioctlfd == -1) {
 553                 if (autofs_type_any(type))
 554                         err = kern_path_mountpoint(AT_FDCWD,
 555                                                    name, &path, LOOKUP_FOLLOW);
 556                 else
 557                         err = find_autofs_mount(name, &path,
 558                                                 test_by_type, &type);
 559                 if (err)
 560                         goto out;
 561                 devid = new_encode_dev(path.dentry->d_sb->s_dev);
 562                 err = 0;
 563                 if (path.mnt->mnt_root == path.dentry) {
 564                         err = 1;
 565                         magic = path.dentry->d_sb->s_magic;
 566                 }
 567         } else {
 568                 dev_t dev = sbi->sb->s_dev;
 569
 570                 err = find_autofs_mount(name, &path, test_by_dev, &dev);
 571                 if (err)
 572                         goto out;
 573
 574                 devid = new_encode_dev(dev);
 575
 576                 err = path_has_submounts(&path);
 577
 578                 if (follow_down_one(&path))
 579                         magic = path.dentry->d_sb->s_magic;
 580         }
 581
 582         param->ismountpoint.out.devid = devid;
 583         param->ismountpoint.out.magic = magic;
 584         path_put(&path);
 585 out:
 586         return err;
 587 }
 588
 589 /*
 590  * Our range of ioctl numbers isn't 0 based so we need to shift
 591  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 592  * lookup.
 593  */
 594 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 595
 596 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 597 {
 598         static ioctl_fn _ioctls[] = {
 599                 autofs_dev_ioctl_version,
 600                 autofs_dev_ioctl_protover,
 601                 autofs_dev_ioctl_protosubver,
 602                 autofs_dev_ioctl_openmount,
 603                 autofs_dev_ioctl_closemount,
 604                 autofs_dev_ioctl_ready,
 605                 autofs_dev_ioctl_fail,
 606                 autofs_dev_ioctl_setpipefd,
 607                 autofs_dev_ioctl_catatonic,
 608                 autofs_dev_ioctl_timeout,
 609                 autofs_dev_ioctl_requester,
 610                 autofs_dev_ioctl_expire,
 611                 autofs_dev_ioctl_askumount,
 612                 autofs_dev_ioctl_ismountpoint,
 613         };
 614         unsigned int idx = cmd_idx(cmd);
 615
 616         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
 617 }
 618
 619 /* ioctl dispatcher */
 620 static int _autofs_dev_ioctl(unsigned int command,
 621                              struct autofs_dev_ioctl __user *user)
 622 {
 623         struct autofs_dev_ioctl *param;
 624         struct file *fp;
 625         struct autofs_sb_info *sbi;
 626         unsigned int cmd_first, cmd;
 627         ioctl_fn fn = NULL;
 628         int err = 0;
 629
 630         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 631         cmd = _IOC_NR(command);
 632
 633         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 634             cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
 635                 return -ENOTTY;
 636         }
 637
 638         /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
 639          * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
 640          */
 641         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 642             cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
 643             !capable(CAP_SYS_ADMIN))
 644                 return -EPERM;
 645
 646         /* Copy the parameters into kernel space. */
 647         param = copy_dev_ioctl(user);
 648         if (IS_ERR(param))
 649                 return PTR_ERR(param);
 650
 651         err = validate_dev_ioctl(command, param);
 652         if (err)
 653                 goto out;
 654
 655         fn = lookup_dev_ioctl(cmd);
 656         if (!fn) {
 657                 pr_warn("unknown command 0x%08x\n", command);
 658                 err = -ENOTTY;
 659                 goto out;
 660         }
 661
 662         fp = NULL;
 663         sbi = NULL;
 664
 665         /*
 666          * For obvious reasons the openmount can't have a file
 667          * descriptor yet. We don't take a reference to the
 668          * file during close to allow for immediate release,
 669          * and the same for retrieving ioctl version.
 670          */
 671         if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
 672             cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 673             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 674                 fp = fget(param->ioctlfd);
 675                 if (!fp) {
 676                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 677                                 goto cont;
 678                         err = -EBADF;
 679                         goto out;
 680                 }
 681
 682                 sbi = autofs_dev_ioctl_sbi(fp);
 683                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 684                         err = -EINVAL;
 685                         fput(fp);
 686                         goto out;
 687                 }
 688
 689                 /*
 690                  * Admin needs to be able to set the mount catatonic in
 691                  * order to be able to perform the re-open.
 692                  */
 693                 if (!autofs4_oz_mode(sbi) &&
 694                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 695                         err = -EACCES;
 696                         fput(fp);
 697                         goto out;
 698                 }
 699         }
 700 cont:
 701         err = fn(fp, sbi, param);
 702
 703         if (fp)
 704                 fput(fp);
 705         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 706                 err = -EFAULT;
 707 out:
 708         free_dev_ioctl(param);
 709         return err;
 710 }
 711
 712 static long autofs_dev_ioctl(struct file *file, unsigned int command,
 713                              unsigned long u)
 714 {
 715         int err;
 716
 717         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 718         return (long) err;
 719 }
 720
 721 #ifdef CONFIG_COMPAT
 722 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
 723                                     unsigned long u)
 724 {
 725         return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
 726 }
 727 #else
 728 #define autofs_dev_ioctl_compat NULL
 729 #endif
 730
 731 static const struct file_operations _dev_ioctl_fops = {
 732         .unlocked_ioctl  = autofs_dev_ioctl,
 733         .compat_ioctl = autofs_dev_ioctl_compat,
 734         .owner   = THIS_MODULE,
 735         .llseek = noop_llseek,
 736 };
 737
 738 static struct miscdevice _autofs_dev_ioctl_misc = {
 739         .minor          = AUTOFS_MINOR,
 740         .name           = AUTOFS_DEVICE_NAME,
 741         .fops           = &_dev_ioctl_fops,
 742         .mode           = 0644,
 743 };
 744
 745 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
 746 MODULE_ALIAS("devname:autofs");
 747
 748 /* Register/deregister misc character device */
 749 int __init autofs_dev_ioctl_init(void)
 750 {
 751         int r;
 752
 753         r = misc_register(&_autofs_dev_ioctl_misc);
 754         if (r) {
 755                 pr_err("misc_register failed for control device\n");
 756                 return r;
 757         }
 758
 759         return 0;
 760 }
 761
 762 void autofs_dev_ioctl_exit(void)
 763 {
 764         misc_deregister(&_autofs_dev_ioctl_misc);
 765 }