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/smp_lock.h>
  23 #include <linux/magic.h>
  24 #include <linux/dcache.h>
  25 #include <linux/uaccess.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, *ads;
  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         ads = kmalloc(tmp.size, GFP_KERNEL);
 107         if (!ads)
 108                 return ERR_PTR(-ENOMEM);
 109
 110         if (copy_from_user(ads, in, tmp.size)) {
 111                 kfree(ads);
 112                 return ERR_PTR(-EFAULT);
 113         }
 114
 115         return ads;
 116 }
 117
 118 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
 119 {
 120         kfree(param);
 121         return;
 122 }
 123
 124 /*
 125  * Check sanity of parameter control fields and if a path is present
 126  * check that it is terminated and contains at least one "/".
 127  */
 128 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
 129 {
 130         int err;
 131
 132         err = check_dev_ioctl_version(cmd, param);
 133         if (err) {
 134                 AUTOFS_WARN("invalid device control module version "
 135                      "supplied for cmd(0x%08x)", cmd);
 136                 goto out;
 137         }
 138
 139         if (param->size > sizeof(*param)) {
 140                 err = invalid_str(param->path, param->size - sizeof(*param));
 141                 if (err) {
 142                         AUTOFS_WARN(
 143                           "path string terminator missing for cmd(0x%08x)",
 144                           cmd);
 145                         goto out;
 146                 }
 147
 148                 err = check_name(param->path);
 149                 if (err) {
 150                         AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
 151                                     cmd);
 152                         goto out;
 153                 }
 154         }
 155
 156         err = 0;
 157 out:
 158         return err;
 159 }
 160
 161 /*
 162  * Get the autofs super block info struct from the file opened on
 163  * the autofs mount point.
 164  */
 165 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
 166 {
 167         struct autofs_sb_info *sbi = NULL;
 168         struct inode *inode;
 169
 170         if (f) {
 171                 inode = f->f_path.dentry->d_inode;
 172                 sbi = autofs4_sbi(inode->i_sb);
 173         }
 174         return sbi;
 175 }
 176
 177 /* Return autofs module protocol version */
 178 static int autofs_dev_ioctl_protover(struct file *fp,
 179                                      struct autofs_sb_info *sbi,
 180                                      struct autofs_dev_ioctl *param)
 181 {
 182         param->protover.version = sbi->version;
 183         return 0;
 184 }
 185
 186 /* Return autofs module protocol sub version */
 187 static int autofs_dev_ioctl_protosubver(struct file *fp,
 188                                         struct autofs_sb_info *sbi,
 189                                         struct autofs_dev_ioctl *param)
 190 {
 191         param->protosubver.sub_version = sbi->sub_version;
 192         return 0;
 193 }
 194
 195 /*
 196  * Walk down the mount stack looking for an autofs mount that
 197  * has the requested device number (aka. new_encode_dev(sb->s_dev).
 198  */
 199 static int autofs_dev_ioctl_find_super(struct nameidata *nd, dev_t devno)
 200 {
 201         struct dentry *dentry;
 202         struct inode *inode;
 203         struct super_block *sb;
 204         dev_t s_dev;
 205         unsigned int err;
 206
 207         err = -ENOENT;
 208
 209         /* Lookup the dentry name at the base of our mount point */
 210         dentry = d_lookup(nd->path.dentry, &nd->last);
 211         if (!dentry)
 212                 goto out;
 213
 214         dput(nd->path.dentry);
 215         nd->path.dentry = dentry;
 216
 217         /* And follow the mount stack looking for our autofs mount */
 218         while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
 219                 inode = nd->path.dentry->d_inode;
 220                 if (!inode)
 221                         break;
 222
 223                 sb = inode->i_sb;
 224                 s_dev = new_encode_dev(sb->s_dev);
 225                 if (devno == s_dev) {
 226                         if (sb->s_magic == AUTOFS_SUPER_MAGIC) {
 227                                 err = 0;
 228                                 break;
 229                         }
 230                 }
 231         }
 232 out:
 233         return err;
 234 }
 235
 236 /*
 237  * Walk down the mount stack looking for an autofs mount that
 238  * has the requested mount type (ie. indirect, direct or offset).
 239  */
 240 static int autofs_dev_ioctl_find_sbi_type(struct nameidata *nd, unsigned int type)
 241 {
 242         struct dentry *dentry;
 243         struct autofs_info *ino;
 244         unsigned int err;
 245
 246         err = -ENOENT;
 247
 248         /* Lookup the dentry name at the base of our mount point */
 249         dentry = d_lookup(nd->path.dentry, &nd->last);
 250         if (!dentry)
 251                 goto out;
 252
 253         dput(nd->path.dentry);
 254         nd->path.dentry = dentry;
 255
 256         /* And follow the mount stack looking for our autofs mount */
 257         while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
 258                 ino = autofs4_dentry_ino(nd->path.dentry);
 259                 if (ino && ino->sbi->type & type) {
 260                         err = 0;
 261                         break;
 262                 }
 263         }
 264 out:
 265         return err;
 266 }
 267
 268 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
 269 {
 270         struct files_struct *files = current->files;
 271         struct fdtable *fdt;
 272
 273         spin_lock(&files->file_lock);
 274         fdt = files_fdtable(files);
 275         BUG_ON(fdt->fd[fd] != NULL);
 276         rcu_assign_pointer(fdt->fd[fd], file);
 277         FD_SET(fd, fdt->close_on_exec);
 278         spin_unlock(&files->file_lock);
 279 }
 280
 281
 282 /*
 283  * Open a file descriptor on the autofs mount point corresponding
 284  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 285  */
 286 static int autofs_dev_ioctl_open_mountpoint(const char *path, dev_t devid)
 287 {
 288         struct file *filp;
 289         struct nameidata nd;
 290         int err, fd;
 291
 292         fd = get_unused_fd();
 293         if (likely(fd >= 0)) {
 294                 /* Get nameidata of the parent directory */
 295                 err = path_lookup(path, LOOKUP_PARENT, &nd);
 296                 if (err)
 297                         goto out;
 298
 299                 /*
 300                  * Search down, within the parent, looking for an
 301                  * autofs super block that has the device number
 302                  * corresponding to the autofs fs we want to open.
 303                  */
 304                 err = autofs_dev_ioctl_find_super(&nd, devid);
 305                 if (err) {
 306                         path_put(&nd.path);
 307                         goto out;
 308                 }
 309
 310                 filp = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY,
 311                                    current_cred());
 312                 if (IS_ERR(filp)) {
 313                         err = PTR_ERR(filp);
 314                         goto out;
 315                 }
 316
 317                 autofs_dev_ioctl_fd_install(fd, filp);
 318         }
 319
 320         return fd;
 321
 322 out:
 323         put_unused_fd(fd);
 324         return err;
 325 }
 326
 327 /* Open a file descriptor on an autofs mount point */
 328 static int autofs_dev_ioctl_openmount(struct file *fp,
 329                                       struct autofs_sb_info *sbi,
 330                                       struct autofs_dev_ioctl *param)
 331 {
 332         const char *path;
 333         dev_t devid;
 334         int err, fd;
 335
 336         /* param->path has already been checked */
 337         if (!param->openmount.devid)
 338                 return -EINVAL;
 339
 340         param->ioctlfd = -1;
 341
 342         path = param->path;
 343         devid = param->openmount.devid;
 344
 345         err = 0;
 346         fd = autofs_dev_ioctl_open_mountpoint(path, devid);
 347         if (unlikely(fd < 0)) {
 348                 err = fd;
 349                 goto out;
 350         }
 351
 352         param->ioctlfd = fd;
 353 out:
 354         return err;
 355 }
 356
 357 /* Close file descriptor allocated above (user can also use close(2)). */
 358 static int autofs_dev_ioctl_closemount(struct file *fp,
 359                                        struct autofs_sb_info *sbi,
 360                                        struct autofs_dev_ioctl *param)
 361 {
 362         return sys_close(param->ioctlfd);
 363 }
 364
 365 /*
 366  * Send "ready" status for an existing wait (either a mount or an expire
 367  * request).
 368  */
 369 static int autofs_dev_ioctl_ready(struct file *fp,
 370                                   struct autofs_sb_info *sbi,
 371                                   struct autofs_dev_ioctl *param)
 372 {
 373         autofs_wqt_t token;
 374
 375         token = (autofs_wqt_t) param->ready.token;
 376         return autofs4_wait_release(sbi, token, 0);
 377 }
 378
 379 /*
 380  * Send "fail" status for an existing wait (either a mount or an expire
 381  * request).
 382  */
 383 static int autofs_dev_ioctl_fail(struct file *fp,
 384                                  struct autofs_sb_info *sbi,
 385                                  struct autofs_dev_ioctl *param)
 386 {
 387         autofs_wqt_t token;
 388         int status;
 389
 390         token = (autofs_wqt_t) param->fail.token;
 391         status = param->fail.status ? param->fail.status : -ENOENT;
 392         return autofs4_wait_release(sbi, token, status);
 393 }
 394
 395 /*
 396  * Set the pipe fd for kernel communication to the daemon.
 397  *
 398  * Normally this is set at mount using an option but if we
 399  * are reconnecting to a busy mount then we need to use this
 400  * to tell the autofs mount about the new kernel pipe fd. In
 401  * order to protect mounts against incorrectly setting the
 402  * pipefd we also require that the autofs mount be catatonic.
 403  *
 404  * This also sets the process group id used to identify the
 405  * controlling process (eg. the owning automount(8) daemon).
 406  */
 407 static int autofs_dev_ioctl_setpipefd(struct file *fp,
 408                                       struct autofs_sb_info *sbi,
 409                                       struct autofs_dev_ioctl *param)
 410 {
 411         int pipefd;
 412         int err = 0;
 413
 414         if (param->setpipefd.pipefd == -1)
 415                 return -EINVAL;
 416
 417         pipefd = param->setpipefd.pipefd;
 418
 419         mutex_lock(&sbi->wq_mutex);
 420         if (!sbi->catatonic) {
 421                 mutex_unlock(&sbi->wq_mutex);
 422                 return -EBUSY;
 423         } else {
 424                 struct file *pipe = fget(pipefd);
 425                 if (!pipe->f_op || !pipe->f_op->write) {
 426                         err = -EPIPE;
 427                         fput(pipe);
 428                         goto out;
 429                 }
 430                 sbi->oz_pgrp = task_pgrp_nr(current);
 431                 sbi->pipefd = pipefd;
 432                 sbi->pipe = pipe;
 433                 sbi->catatonic = 0;
 434         }
 435 out:
 436         mutex_unlock(&sbi->wq_mutex);
 437         return err;
 438 }
 439
 440 /*
 441  * Make the autofs mount point catatonic, no longer responsive to
 442  * mount requests. Also closes the kernel pipe file descriptor.
 443  */
 444 static int autofs_dev_ioctl_catatonic(struct file *fp,
 445                                       struct autofs_sb_info *sbi,
 446                                       struct autofs_dev_ioctl *param)
 447 {
 448         autofs4_catatonic_mode(sbi);
 449         return 0;
 450 }
 451
 452 /* Set the autofs mount timeout */
 453 static int autofs_dev_ioctl_timeout(struct file *fp,
 454                                     struct autofs_sb_info *sbi,
 455                                     struct autofs_dev_ioctl *param)
 456 {
 457         unsigned long timeout;
 458
 459         timeout = param->timeout.timeout;
 460         param->timeout.timeout = sbi->exp_timeout / HZ;
 461         sbi->exp_timeout = timeout * HZ;
 462         return 0;
 463 }
 464
 465 /*
 466  * Return the uid and gid of the last request for the mount
 467  *
 468  * When reconstructing an autofs mount tree with active mounts
 469  * we need to re-connect to mounts that may have used the original
 470  * process uid and gid (or string variations of them) for mount
 471  * lookups within the map entry.
 472  */
 473 static int autofs_dev_ioctl_requester(struct file *fp,
 474                                       struct autofs_sb_info *sbi,
 475                                       struct autofs_dev_ioctl *param)
 476 {
 477         struct autofs_info *ino;
 478         struct nameidata nd;
 479         const char *path;
 480         dev_t devid;
 481         int err = -ENOENT;
 482
 483         if (param->size <= sizeof(*param)) {
 484                 err = -EINVAL;
 485                 goto out;
 486         }
 487
 488         path = param->path;
 489         devid = new_encode_dev(sbi->sb->s_dev);
 490
 491         param->requester.uid = param->requester.gid = -1;
 492
 493         /* Get nameidata of the parent directory */
 494         err = path_lookup(path, LOOKUP_PARENT, &nd);
 495         if (err)
 496                 goto out;
 497
 498         err = autofs_dev_ioctl_find_super(&nd, devid);
 499         if (err)
 500                 goto out_release;
 501
 502         ino = autofs4_dentry_ino(nd.path.dentry);
 503         if (ino) {
 504                 err = 0;
 505                 autofs4_expire_wait(nd.path.dentry);
 506                 spin_lock(&sbi->fs_lock);
 507                 param->requester.uid = ino->uid;
 508                 param->requester.gid = ino->gid;
 509                 spin_unlock(&sbi->fs_lock);
 510         }
 511
 512 out_release:
 513         path_put(&nd.path);
 514 out:
 515         return err;
 516 }
 517
 518 /*
 519  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 520  * more that can be done.
 521  */
 522 static int autofs_dev_ioctl_expire(struct file *fp,
 523                                    struct autofs_sb_info *sbi,
 524                                    struct autofs_dev_ioctl *param)
 525 {
 526         struct vfsmount *mnt;
 527         int how;
 528
 529         how = param->expire.how;
 530         mnt = fp->f_path.mnt;
 531
 532         return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
 533 }
 534
 535 /* Check if autofs mount point is in use */
 536 static int autofs_dev_ioctl_askumount(struct file *fp,
 537                                       struct autofs_sb_info *sbi,
 538                                       struct autofs_dev_ioctl *param)
 539 {
 540         param->askumount.may_umount = 0;
 541         if (may_umount(fp->f_path.mnt))
 542                 param->askumount.may_umount = 1;
 543         return 0;
 544 }
 545
 546 /*
 547  * Check if the given path is a mountpoint.
 548  *
 549  * If we are supplied with the file descriptor of an autofs
 550  * mount we're looking for a specific mount. In this case
 551  * the path is considered a mountpoint if it is itself a
 552  * mountpoint or contains a mount, such as a multi-mount
 553  * without a root mount. In this case we return 1 if the
 554  * path is a mount point and the super magic of the covering
 555  * mount if there is one or 0 if it isn't a mountpoint.
 556  *
 557  * If we aren't supplied with a file descriptor then we
 558  * lookup the nameidata of the path and check if it is the
 559  * root of a mount. If a type is given we are looking for
 560  * a particular autofs mount and if we don't find a match
 561  * we return fail. If the located nameidata path is the
 562  * root of a mount we return 1 along with the super magic
 563  * of the mount or 0 otherwise.
 564  *
 565  * In both cases the the device number (as returned by
 566  * new_encode_dev()) is also returned.
 567  */
 568 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
 569                                          struct autofs_sb_info *sbi,
 570                                          struct autofs_dev_ioctl *param)
 571 {
 572         struct nameidata nd;
 573         const char *path;
 574         unsigned int type;
 575         unsigned int devid, magic;
 576         int err = -ENOENT;
 577
 578         if (param->size <= sizeof(*param)) {
 579                 err = -EINVAL;
 580                 goto out;
 581         }
 582
 583         path = param->path;
 584         type = param->ismountpoint.in.type;
 585
 586         param->ismountpoint.out.devid = devid = 0;
 587         param->ismountpoint.out.magic = magic = 0;
 588
 589         if (!fp || param->ioctlfd == -1) {
 590                 if (autofs_type_any(type)) {
 591                         struct super_block *sb;
 592
 593                         err = path_lookup(path, LOOKUP_FOLLOW, &nd);
 594                         if (err)
 595                                 goto out;
 596
 597                         sb = nd.path.dentry->d_sb;
 598                         devid = new_encode_dev(sb->s_dev);
 599                 } else {
 600                         struct autofs_info *ino;
 601
 602                         err = path_lookup(path, LOOKUP_PARENT, &nd);
 603                         if (err)
 604                                 goto out;
 605
 606                         err = autofs_dev_ioctl_find_sbi_type(&nd, type);
 607                         if (err)
 608                                 goto out_release;
 609
 610                         ino = autofs4_dentry_ino(nd.path.dentry);
 611                         devid = autofs4_get_dev(ino->sbi);
 612                 }
 613
 614                 err = 0;
 615                 if (nd.path.dentry->d_inode &&
 616                     nd.path.mnt->mnt_root == nd.path.dentry) {
 617                         err = 1;
 618                         magic = nd.path.dentry->d_inode->i_sb->s_magic;
 619                 }
 620         } else {
 621                 dev_t dev = autofs4_get_dev(sbi);
 622
 623                 err = path_lookup(path, LOOKUP_PARENT, &nd);
 624                 if (err)
 625                         goto out;
 626
 627                 err = autofs_dev_ioctl_find_super(&nd, dev);
 628                 if (err)
 629                         goto out_release;
 630
 631                 devid = dev;
 632
 633                 err = have_submounts(nd.path.dentry);
 634
 635                 if (nd.path.mnt->mnt_mountpoint != nd.path.mnt->mnt_root) {
 636                         if (follow_down(&nd.path.mnt, &nd.path.dentry)) {
 637                                 struct inode *inode = nd.path.dentry->d_inode;
 638                                 magic = inode->i_sb->s_magic;
 639                         }
 640                 }
 641         }
 642
 643         param->ismountpoint.out.devid = devid;
 644         param->ismountpoint.out.magic = magic;
 645
 646 out_release:
 647         path_put(&nd.path);
 648 out:
 649         return err;
 650 }
 651
 652 /*
 653  * Our range of ioctl numbers isn't 0 based so we need to shift
 654  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 655  * lookup.
 656  */
 657 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
 658
 659 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
 660 {
 661         static struct {
 662                 int cmd;
 663                 ioctl_fn fn;
 664         } _ioctls[] = {
 665                 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
 666                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
 667                          autofs_dev_ioctl_protover},
 668                 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
 669                          autofs_dev_ioctl_protosubver},
 670                 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
 671                          autofs_dev_ioctl_openmount},
 672                 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
 673                          autofs_dev_ioctl_closemount},
 674                 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
 675                          autofs_dev_ioctl_ready},
 676                 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
 677                          autofs_dev_ioctl_fail},
 678                 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
 679                          autofs_dev_ioctl_setpipefd},
 680                 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
 681                          autofs_dev_ioctl_catatonic},
 682                 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
 683                          autofs_dev_ioctl_timeout},
 684                 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
 685                          autofs_dev_ioctl_requester},
 686                 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
 687                          autofs_dev_ioctl_expire},
 688                 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
 689                          autofs_dev_ioctl_askumount},
 690                 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
 691                          autofs_dev_ioctl_ismountpoint}
 692         };
 693         unsigned int idx = cmd_idx(cmd);
 694
 695         return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
 696 }
 697
 698 /* ioctl dispatcher */
 699 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
 700 {
 701         struct autofs_dev_ioctl *param;
 702         struct file *fp;
 703         struct autofs_sb_info *sbi;
 704         unsigned int cmd_first, cmd;
 705         ioctl_fn fn = NULL;
 706         int err = 0;
 707
 708         /* only root can play with this */
 709         if (!capable(CAP_SYS_ADMIN))
 710                 return -EPERM;
 711
 712         cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
 713         cmd = _IOC_NR(command);
 714
 715         if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
 716             cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
 717                 return -ENOTTY;
 718         }
 719
 720         /* Copy the parameters into kernel space. */
 721         param = copy_dev_ioctl(user);
 722         if (IS_ERR(param))
 723                 return PTR_ERR(param);
 724
 725         err = validate_dev_ioctl(command, param);
 726         if (err)
 727                 goto out;
 728
 729         /* The validate routine above always sets the version */
 730         if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
 731                 goto done;
 732
 733         fn = lookup_dev_ioctl(cmd);
 734         if (!fn) {
 735                 AUTOFS_WARN("unknown command 0x%08x", command);
 736                 return -ENOTTY;
 737         }
 738
 739         fp = NULL;
 740         sbi = NULL;
 741
 742         /*
 743          * For obvious reasons the openmount can't have a file
 744          * descriptor yet. We don't take a reference to the
 745          * file during close to allow for immediate release.
 746          */
 747         if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
 748             cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
 749                 fp = fget(param->ioctlfd);
 750                 if (!fp) {
 751                         if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
 752                                 goto cont;
 753                         err = -EBADF;
 754                         goto out;
 755                 }
 756
 757                 if (!fp->f_op) {
 758                         err = -ENOTTY;
 759                         fput(fp);
 760                         goto out;
 761                 }
 762
 763                 sbi = autofs_dev_ioctl_sbi(fp);
 764                 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
 765                         err = -EINVAL;
 766                         fput(fp);
 767                         goto out;
 768                 }
 769
 770                 /*
 771                  * Admin needs to be able to set the mount catatonic in
 772                  * order to be able to perform the re-open.
 773                  */
 774                 if (!autofs4_oz_mode(sbi) &&
 775                     cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
 776                         err = -EACCES;
 777                         fput(fp);
 778                         goto out;
 779                 }
 780         }
 781 cont:
 782         err = fn(fp, sbi, param);
 783
 784         if (fp)
 785                 fput(fp);
 786 done:
 787         if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
 788                 err = -EFAULT;
 789 out:
 790         free_dev_ioctl(param);
 791         return err;
 792 }
 793
 794 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
 795 {
 796         int err;
 797         err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
 798         return (long) err;
 799 }
 800
 801 #ifdef CONFIG_COMPAT
 802 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
 803 {
 804         return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
 805 }
 806 #else
 807 #define autofs_dev_ioctl_compat NULL
 808 #endif
 809
 810 static const struct file_operations _dev_ioctl_fops = {
 811         .unlocked_ioctl  = autofs_dev_ioctl,
 812         .compat_ioctl = autofs_dev_ioctl_compat,
 813         .owner   = THIS_MODULE,
 814 };
 815
 816 static struct miscdevice _autofs_dev_ioctl_misc = {
 817         .minor          = MISC_DYNAMIC_MINOR,
 818         .name           = AUTOFS_DEVICE_NAME,
 819         .fops           = &_dev_ioctl_fops
 820 };
 821
 822 /* Register/deregister misc character device */
 823 int autofs_dev_ioctl_init(void)
 824 {
 825         int r;
 826
 827         r = misc_register(&_autofs_dev_ioctl_misc);
 828         if (r) {
 829                 AUTOFS_ERROR("misc_register failed for control device");
 830                 return r;
 831         }
 832
 833         return 0;
 834 }
 835
 836 void autofs_dev_ioctl_exit(void)
 837 {
 838         misc_deregister(&_autofs_dev_ioctl_misc);
 839         return;
 840 }
 841