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0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Copyright 2008 Red Hat, Inc. All rights reserved.
0004  * Copyright 2008 Ian Kent <raven@themaw.net>
0005  */
0006 
0007 #include <linux/module.h>
0008 #include <linux/miscdevice.h>
0009 #include <linux/compat.h>
0010 #include <linux/fdtable.h>
0011 #include <linux/magic.h>
0012 #include <linux/nospec.h>
0013 
0014 #include "autofs_i.h"
0015 
0016 /*
0017  * This module implements an interface for routing autofs ioctl control
0018  * commands via a miscellaneous device file.
0019  *
0020  * The alternate interface is needed because we need to be able open
0021  * an ioctl file descriptor on an autofs mount that may be covered by
0022  * another mount. This situation arises when starting automount(8)
0023  * or other user space daemon which uses direct mounts or offset
0024  * mounts (used for autofs lazy mount/umount of nested mount trees),
0025  * which have been left busy at service shutdown.
0026  */
0027 
0028 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
0029             struct autofs_dev_ioctl *);
0030 
0031 static int check_name(const char *name)
0032 {
0033     if (!strchr(name, '/'))
0034         return -EINVAL;
0035     return 0;
0036 }
0037 
0038 /*
0039  * Check a string doesn't overrun the chunk of
0040  * memory we copied from user land.
0041  */
0042 static int invalid_str(char *str, size_t size)
0043 {
0044     if (memchr(str, 0, size))
0045         return 0;
0046     return -EINVAL;
0047 }
0048 
0049 /*
0050  * Check that the user compiled against correct version of autofs
0051  * misc device code.
0052  *
0053  * As well as checking the version compatibility this always copies
0054  * the kernel interface version out.
0055  */
0056 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
0057 {
0058     int err = 0;
0059 
0060     if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
0061         (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
0062         pr_warn("ioctl control interface version mismatch: "
0063             "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
0064             AUTOFS_DEV_IOCTL_VERSION_MAJOR,
0065             AUTOFS_DEV_IOCTL_VERSION_MINOR,
0066             param->ver_major, param->ver_minor, cmd);
0067         err = -EINVAL;
0068     }
0069 
0070     /* Fill in the kernel version. */
0071     param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
0072     param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
0073 
0074     return err;
0075 }
0076 
0077 /*
0078  * Copy parameter control struct, including a possible path allocated
0079  * at the end of the struct.
0080  */
0081 static struct autofs_dev_ioctl *
0082 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
0083 {
0084     struct autofs_dev_ioctl tmp, *res;
0085 
0086     if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
0087         return ERR_PTR(-EFAULT);
0088 
0089     if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
0090         return ERR_PTR(-EINVAL);
0091 
0092     if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
0093         return ERR_PTR(-ENAMETOOLONG);
0094 
0095     res = memdup_user(in, tmp.size);
0096     if (!IS_ERR(res))
0097         res->size = tmp.size;
0098 
0099     return res;
0100 }
0101 
0102 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
0103 {
0104     kfree(param);
0105 }
0106 
0107 /*
0108  * Check sanity of parameter control fields and if a path is present
0109  * check that it is terminated and contains at least one "/".
0110  */
0111 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
0112 {
0113     int err;
0114 
0115     err = check_dev_ioctl_version(cmd, param);
0116     if (err) {
0117         pr_warn("invalid device control module version "
0118             "supplied for cmd(0x%08x)\n", cmd);
0119         goto out;
0120     }
0121 
0122     if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
0123         err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
0124         if (err) {
0125             pr_warn(
0126               "path string terminator missing for cmd(0x%08x)\n",
0127               cmd);
0128             goto out;
0129         }
0130 
0131         err = check_name(param->path);
0132         if (err) {
0133             pr_warn("invalid path supplied for cmd(0x%08x)\n",
0134                 cmd);
0135             goto out;
0136         }
0137     } else {
0138         unsigned int inr = _IOC_NR(cmd);
0139 
0140         if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
0141             inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
0142             inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
0143             err = -EINVAL;
0144             goto out;
0145         }
0146     }
0147 
0148     err = 0;
0149 out:
0150     return err;
0151 }
0152 
0153 /* Return autofs dev ioctl version */
0154 static int autofs_dev_ioctl_version(struct file *fp,
0155                     struct autofs_sb_info *sbi,
0156                     struct autofs_dev_ioctl *param)
0157 {
0158     /* This should have already been set. */
0159     param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
0160     param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
0161     return 0;
0162 }
0163 
0164 /* Return autofs module protocol version */
0165 static int autofs_dev_ioctl_protover(struct file *fp,
0166                      struct autofs_sb_info *sbi,
0167                      struct autofs_dev_ioctl *param)
0168 {
0169     param->protover.version = sbi->version;
0170     return 0;
0171 }
0172 
0173 /* Return autofs module protocol sub version */
0174 static int autofs_dev_ioctl_protosubver(struct file *fp,
0175                     struct autofs_sb_info *sbi,
0176                     struct autofs_dev_ioctl *param)
0177 {
0178     param->protosubver.sub_version = sbi->sub_version;
0179     return 0;
0180 }
0181 
0182 /* Find the topmost mount satisfying test() */
0183 static int find_autofs_mount(const char *pathname,
0184                  struct path *res,
0185                  int test(const struct path *path, void *data),
0186                  void *data)
0187 {
0188     struct path path;
0189     int err;
0190 
0191     err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
0192     if (err)
0193         return err;
0194     err = -ENOENT;
0195     while (path.dentry == path.mnt->mnt_root) {
0196         if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
0197             if (test(&path, data)) {
0198                 path_get(&path);
0199                 *res = path;
0200                 err = 0;
0201                 break;
0202             }
0203         }
0204         if (!follow_up(&path))
0205             break;
0206     }
0207     path_put(&path);
0208     return err;
0209 }
0210 
0211 static int test_by_dev(const struct path *path, void *p)
0212 {
0213     return path->dentry->d_sb->s_dev == *(dev_t *)p;
0214 }
0215 
0216 static int test_by_type(const struct path *path, void *p)
0217 {
0218     struct autofs_info *ino = autofs_dentry_ino(path->dentry);
0219 
0220     return ino && ino->sbi->type & *(unsigned *)p;
0221 }
0222 
0223 /*
0224  * Open a file descriptor on the autofs mount point corresponding
0225  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
0226  */
0227 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
0228 {
0229     int err, fd;
0230 
0231     fd = get_unused_fd_flags(O_CLOEXEC);
0232     if (likely(fd >= 0)) {
0233         struct file *filp;
0234         struct path path;
0235 
0236         err = find_autofs_mount(name, &path, test_by_dev, &devid);
0237         if (err)
0238             goto out;
0239 
0240         filp = dentry_open(&path, O_RDONLY, current_cred());
0241         path_put(&path);
0242         if (IS_ERR(filp)) {
0243             err = PTR_ERR(filp);
0244             goto out;
0245         }
0246 
0247         fd_install(fd, filp);
0248     }
0249 
0250     return fd;
0251 
0252 out:
0253     put_unused_fd(fd);
0254     return err;
0255 }
0256 
0257 /* Open a file descriptor on an autofs mount point */
0258 static int autofs_dev_ioctl_openmount(struct file *fp,
0259                       struct autofs_sb_info *sbi,
0260                       struct autofs_dev_ioctl *param)
0261 {
0262     const char *path;
0263     dev_t devid;
0264     int err, fd;
0265 
0266     /* param->path has been checked in validate_dev_ioctl() */
0267 
0268     if (!param->openmount.devid)
0269         return -EINVAL;
0270 
0271     param->ioctlfd = -1;
0272 
0273     path = param->path;
0274     devid = new_decode_dev(param->openmount.devid);
0275 
0276     err = 0;
0277     fd = autofs_dev_ioctl_open_mountpoint(path, devid);
0278     if (unlikely(fd < 0)) {
0279         err = fd;
0280         goto out;
0281     }
0282 
0283     param->ioctlfd = fd;
0284 out:
0285     return err;
0286 }
0287 
0288 /* Close file descriptor allocated above (user can also use close(2)). */
0289 static int autofs_dev_ioctl_closemount(struct file *fp,
0290                        struct autofs_sb_info *sbi,
0291                        struct autofs_dev_ioctl *param)
0292 {
0293     return close_fd(param->ioctlfd);
0294 }
0295 
0296 /*
0297  * Send "ready" status for an existing wait (either a mount or an expire
0298  * request).
0299  */
0300 static int autofs_dev_ioctl_ready(struct file *fp,
0301                   struct autofs_sb_info *sbi,
0302                   struct autofs_dev_ioctl *param)
0303 {
0304     autofs_wqt_t token;
0305 
0306     token = (autofs_wqt_t) param->ready.token;
0307     return autofs_wait_release(sbi, token, 0);
0308 }
0309 
0310 /*
0311  * Send "fail" status for an existing wait (either a mount or an expire
0312  * request).
0313  */
0314 static int autofs_dev_ioctl_fail(struct file *fp,
0315                  struct autofs_sb_info *sbi,
0316                  struct autofs_dev_ioctl *param)
0317 {
0318     autofs_wqt_t token;
0319     int status;
0320 
0321     token = (autofs_wqt_t) param->fail.token;
0322     status = param->fail.status < 0 ? param->fail.status : -ENOENT;
0323     return autofs_wait_release(sbi, token, status);
0324 }
0325 
0326 /*
0327  * Set the pipe fd for kernel communication to the daemon.
0328  *
0329  * Normally this is set at mount using an option but if we
0330  * are reconnecting to a busy mount then we need to use this
0331  * to tell the autofs mount about the new kernel pipe fd. In
0332  * order to protect mounts against incorrectly setting the
0333  * pipefd we also require that the autofs mount be catatonic.
0334  *
0335  * This also sets the process group id used to identify the
0336  * controlling process (eg. the owning automount(8) daemon).
0337  */
0338 static int autofs_dev_ioctl_setpipefd(struct file *fp,
0339                       struct autofs_sb_info *sbi,
0340                       struct autofs_dev_ioctl *param)
0341 {
0342     int pipefd;
0343     int err = 0;
0344     struct pid *new_pid = NULL;
0345 
0346     if (param->setpipefd.pipefd == -1)
0347         return -EINVAL;
0348 
0349     pipefd = param->setpipefd.pipefd;
0350 
0351     mutex_lock(&sbi->wq_mutex);
0352     if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
0353         mutex_unlock(&sbi->wq_mutex);
0354         return -EBUSY;
0355     } else {
0356         struct file *pipe;
0357 
0358         new_pid = get_task_pid(current, PIDTYPE_PGID);
0359 
0360         if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
0361             pr_warn("not allowed to change PID namespace\n");
0362             err = -EINVAL;
0363             goto out;
0364         }
0365 
0366         pipe = fget(pipefd);
0367         if (!pipe) {
0368             err = -EBADF;
0369             goto out;
0370         }
0371         if (autofs_prepare_pipe(pipe) < 0) {
0372             err = -EPIPE;
0373             fput(pipe);
0374             goto out;
0375         }
0376         swap(sbi->oz_pgrp, new_pid);
0377         sbi->pipefd = pipefd;
0378         sbi->pipe = pipe;
0379         sbi->flags &= ~AUTOFS_SBI_CATATONIC;
0380     }
0381 out:
0382     put_pid(new_pid);
0383     mutex_unlock(&sbi->wq_mutex);
0384     return err;
0385 }
0386 
0387 /*
0388  * Make the autofs mount point catatonic, no longer responsive to
0389  * mount requests. Also closes the kernel pipe file descriptor.
0390  */
0391 static int autofs_dev_ioctl_catatonic(struct file *fp,
0392                       struct autofs_sb_info *sbi,
0393                       struct autofs_dev_ioctl *param)
0394 {
0395     autofs_catatonic_mode(sbi);
0396     return 0;
0397 }
0398 
0399 /* Set the autofs mount timeout */
0400 static int autofs_dev_ioctl_timeout(struct file *fp,
0401                     struct autofs_sb_info *sbi,
0402                     struct autofs_dev_ioctl *param)
0403 {
0404     unsigned long timeout;
0405 
0406     timeout = param->timeout.timeout;
0407     param->timeout.timeout = sbi->exp_timeout / HZ;
0408     sbi->exp_timeout = timeout * HZ;
0409     return 0;
0410 }
0411 
0412 /*
0413  * Return the uid and gid of the last request for the mount
0414  *
0415  * When reconstructing an autofs mount tree with active mounts
0416  * we need to re-connect to mounts that may have used the original
0417  * process uid and gid (or string variations of them) for mount
0418  * lookups within the map entry.
0419  */
0420 static int autofs_dev_ioctl_requester(struct file *fp,
0421                       struct autofs_sb_info *sbi,
0422                       struct autofs_dev_ioctl *param)
0423 {
0424     struct autofs_info *ino;
0425     struct path path;
0426     dev_t devid;
0427     int err = -ENOENT;
0428 
0429     /* param->path has been checked in validate_dev_ioctl() */
0430 
0431     devid = sbi->sb->s_dev;
0432 
0433     param->requester.uid = param->requester.gid = -1;
0434 
0435     err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
0436     if (err)
0437         goto out;
0438 
0439     ino = autofs_dentry_ino(path.dentry);
0440     if (ino) {
0441         err = 0;
0442         autofs_expire_wait(&path, 0);
0443         spin_lock(&sbi->fs_lock);
0444         param->requester.uid =
0445             from_kuid_munged(current_user_ns(), ino->uid);
0446         param->requester.gid =
0447             from_kgid_munged(current_user_ns(), ino->gid);
0448         spin_unlock(&sbi->fs_lock);
0449     }
0450     path_put(&path);
0451 out:
0452     return err;
0453 }
0454 
0455 /*
0456  * Call repeatedly until it returns -EAGAIN, meaning there's nothing
0457  * more that can be done.
0458  */
0459 static int autofs_dev_ioctl_expire(struct file *fp,
0460                    struct autofs_sb_info *sbi,
0461                    struct autofs_dev_ioctl *param)
0462 {
0463     struct vfsmount *mnt;
0464     int how;
0465 
0466     how = param->expire.how;
0467     mnt = fp->f_path.mnt;
0468 
0469     return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
0470 }
0471 
0472 /* Check if autofs mount point is in use */
0473 static int autofs_dev_ioctl_askumount(struct file *fp,
0474                       struct autofs_sb_info *sbi,
0475                       struct autofs_dev_ioctl *param)
0476 {
0477     param->askumount.may_umount = 0;
0478     if (may_umount(fp->f_path.mnt))
0479         param->askumount.may_umount = 1;
0480     return 0;
0481 }
0482 
0483 /*
0484  * Check if the given path is a mountpoint.
0485  *
0486  * If we are supplied with the file descriptor of an autofs
0487  * mount we're looking for a specific mount. In this case
0488  * the path is considered a mountpoint if it is itself a
0489  * mountpoint or contains a mount, such as a multi-mount
0490  * without a root mount. In this case we return 1 if the
0491  * path is a mount point and the super magic of the covering
0492  * mount if there is one or 0 if it isn't a mountpoint.
0493  *
0494  * If we aren't supplied with a file descriptor then we
0495  * lookup the path and check if it is the root of a mount.
0496  * If a type is given we are looking for a particular autofs
0497  * mount and if we don't find a match we return fail. If the
0498  * located path is the root of a mount we return 1 along with
0499  * the super magic of the mount or 0 otherwise.
0500  *
0501  * In both cases the device number (as returned by
0502  * new_encode_dev()) is also returned.
0503  */
0504 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
0505                      struct autofs_sb_info *sbi,
0506                      struct autofs_dev_ioctl *param)
0507 {
0508     struct path path;
0509     const char *name;
0510     unsigned int type;
0511     unsigned int devid, magic;
0512     int err = -ENOENT;
0513 
0514     /* param->path has been checked in validate_dev_ioctl() */
0515 
0516     name = param->path;
0517     type = param->ismountpoint.in.type;
0518 
0519     param->ismountpoint.out.devid = devid = 0;
0520     param->ismountpoint.out.magic = magic = 0;
0521 
0522     if (!fp || param->ioctlfd == -1) {
0523         if (autofs_type_any(type))
0524             err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
0525                     &path);
0526         else
0527             err = find_autofs_mount(name, &path,
0528                         test_by_type, &type);
0529         if (err)
0530             goto out;
0531         devid = new_encode_dev(path.dentry->d_sb->s_dev);
0532         err = 0;
0533         if (path.mnt->mnt_root == path.dentry) {
0534             err = 1;
0535             magic = path.dentry->d_sb->s_magic;
0536         }
0537     } else {
0538         dev_t dev = sbi->sb->s_dev;
0539 
0540         err = find_autofs_mount(name, &path, test_by_dev, &dev);
0541         if (err)
0542             goto out;
0543 
0544         devid = new_encode_dev(dev);
0545 
0546         err = path_has_submounts(&path);
0547 
0548         if (follow_down_one(&path))
0549             magic = path.dentry->d_sb->s_magic;
0550     }
0551 
0552     param->ismountpoint.out.devid = devid;
0553     param->ismountpoint.out.magic = magic;
0554     path_put(&path);
0555 out:
0556     return err;
0557 }
0558 
0559 /*
0560  * Our range of ioctl numbers isn't 0 based so we need to shift
0561  * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
0562  * lookup.
0563  */
0564 #define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
0565 
0566 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
0567 {
0568     static const ioctl_fn _ioctls[] = {
0569         autofs_dev_ioctl_version,
0570         autofs_dev_ioctl_protover,
0571         autofs_dev_ioctl_protosubver,
0572         autofs_dev_ioctl_openmount,
0573         autofs_dev_ioctl_closemount,
0574         autofs_dev_ioctl_ready,
0575         autofs_dev_ioctl_fail,
0576         autofs_dev_ioctl_setpipefd,
0577         autofs_dev_ioctl_catatonic,
0578         autofs_dev_ioctl_timeout,
0579         autofs_dev_ioctl_requester,
0580         autofs_dev_ioctl_expire,
0581         autofs_dev_ioctl_askumount,
0582         autofs_dev_ioctl_ismountpoint,
0583     };
0584     unsigned int idx = cmd_idx(cmd);
0585 
0586     if (idx >= ARRAY_SIZE(_ioctls))
0587         return NULL;
0588     idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls));
0589     return _ioctls[idx];
0590 }
0591 
0592 /* ioctl dispatcher */
0593 static int _autofs_dev_ioctl(unsigned int command,
0594                  struct autofs_dev_ioctl __user *user)
0595 {
0596     struct autofs_dev_ioctl *param;
0597     struct file *fp;
0598     struct autofs_sb_info *sbi;
0599     unsigned int cmd_first, cmd;
0600     ioctl_fn fn = NULL;
0601     int err = 0;
0602 
0603     cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
0604     cmd = _IOC_NR(command);
0605 
0606     if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
0607         cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
0608         return -ENOTTY;
0609     }
0610 
0611     /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
0612      * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
0613      */
0614     if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
0615         cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
0616         !capable(CAP_SYS_ADMIN))
0617         return -EPERM;
0618 
0619     /* Copy the parameters into kernel space. */
0620     param = copy_dev_ioctl(user);
0621     if (IS_ERR(param))
0622         return PTR_ERR(param);
0623 
0624     err = validate_dev_ioctl(command, param);
0625     if (err)
0626         goto out;
0627 
0628     fn = lookup_dev_ioctl(cmd);
0629     if (!fn) {
0630         pr_warn("unknown command 0x%08x\n", command);
0631         err = -ENOTTY;
0632         goto out;
0633     }
0634 
0635     fp = NULL;
0636     sbi = NULL;
0637 
0638     /*
0639      * For obvious reasons the openmount can't have a file
0640      * descriptor yet. We don't take a reference to the
0641      * file during close to allow for immediate release,
0642      * and the same for retrieving ioctl version.
0643      */
0644     if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
0645         cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
0646         cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
0647         struct super_block *sb;
0648 
0649         fp = fget(param->ioctlfd);
0650         if (!fp) {
0651             if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
0652                 goto cont;
0653             err = -EBADF;
0654             goto out;
0655         }
0656 
0657         sb = file_inode(fp)->i_sb;
0658         if (sb->s_type != &autofs_fs_type) {
0659             err = -EINVAL;
0660             fput(fp);
0661             goto out;
0662         }
0663         sbi = autofs_sbi(sb);
0664 
0665         /*
0666          * Admin needs to be able to set the mount catatonic in
0667          * order to be able to perform the re-open.
0668          */
0669         if (!autofs_oz_mode(sbi) &&
0670             cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
0671             err = -EACCES;
0672             fput(fp);
0673             goto out;
0674         }
0675     }
0676 cont:
0677     err = fn(fp, sbi, param);
0678 
0679     if (fp)
0680         fput(fp);
0681     if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
0682         err = -EFAULT;
0683 out:
0684     free_dev_ioctl(param);
0685     return err;
0686 }
0687 
0688 static long autofs_dev_ioctl(struct file *file, unsigned int command,
0689                  unsigned long u)
0690 {
0691     int err;
0692 
0693     err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
0694     return (long) err;
0695 }
0696 
0697 #ifdef CONFIG_COMPAT
0698 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
0699                     unsigned long u)
0700 {
0701     return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
0702 }
0703 #else
0704 #define autofs_dev_ioctl_compat NULL
0705 #endif
0706 
0707 static const struct file_operations _dev_ioctl_fops = {
0708     .unlocked_ioctl  = autofs_dev_ioctl,
0709     .compat_ioctl = autofs_dev_ioctl_compat,
0710     .owner   = THIS_MODULE,
0711     .llseek = noop_llseek,
0712 };
0713 
0714 static struct miscdevice _autofs_dev_ioctl_misc = {
0715     .minor      = AUTOFS_MINOR,
0716     .name       = AUTOFS_DEVICE_NAME,
0717     .fops       = &_dev_ioctl_fops,
0718     .mode           = 0644,
0719 };
0720 
0721 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
0722 MODULE_ALIAS("devname:autofs");
0723 
0724 /* Register/deregister misc character device */
0725 int __init autofs_dev_ioctl_init(void)
0726 {
0727     int r;
0728 
0729     r = misc_register(&_autofs_dev_ioctl_misc);
0730     if (r) {
0731         pr_err("misc_register failed for control device\n");
0732         return r;
0733     }
0734 
0735     return 0;
0736 }
0737 
0738 void autofs_dev_ioctl_exit(void)
0739 {
0740     misc_deregister(&_autofs_dev_ioctl_misc);
0741 }
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