CRED: Pass credentials through dentry_open()

[linux-2.6/mini2440.git] / fs / autofs4 / dev-ioctl.c

/*
 * Copyright 2008 Red Hat, Inc. All rights reserved.
 * Copyright 2008 Ian Kent <raven@themaw.net>
 *
 * This file is part of the Linux kernel and is made available under
 * the terms of the GNU General Public License, version 2, or at your
 * option, any later version, incorporated herein by reference.
 */

#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/miscdevice.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/namei.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/fdtable.h>
#include <linux/sched.h>
#include <linux/compat.h>
#include <linux/syscalls.h>
#include <linux/smp_lock.h>
#include <linux/magic.h>
#include <linux/dcache.h>
#include <linux/uaccess.h>

#include "autofs_i.h"

/*
 * This module implements an interface for routing autofs ioctl control
 * commands via a miscellaneous device file.
 *
 * The alternate interface is needed because we need to be able open
 * an ioctl file descriptor on an autofs mount that may be covered by
 * another mount. This situation arises when starting automount(8)
 * or other user space daemon which uses direct mounts or offset
 * mounts (used for autofs lazy mount/umount of nested mount trees),
 * which have been left busy at at service shutdown.
 */

#define AUTOFS_DEV_IOCTL_SIZE   sizeof(struct autofs_dev_ioctl)

typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
                        struct autofs_dev_ioctl *);

static int check_name(const char *name)
{
        if (!strchr(name, '/'))
                return -EINVAL;
        return 0;
}

/*
 * Check a string doesn't overrun the chunk of
 * memory we copied from user land.
 */
static int invalid_str(char *str, void *end)
{
        while ((void *) str <= end)
                if (!*str++)
                        return 0;
        return -EINVAL;
}

/*
 * Check that the user compiled against correct version of autofs
 * misc device code.
 *
 * As well as checking the version compatibility this always copies
 * the kernel interface version out.
 */
static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
{
        int err = 0;

        if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
            (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
                AUTOFS_WARN("ioctl control interface version mismatch: "
                     "kernel(%u.%u), user(%u.%u), cmd(%d)",
                     AUTOFS_DEV_IOCTL_VERSION_MAJOR,
                     AUTOFS_DEV_IOCTL_VERSION_MINOR,
                     param->ver_major, param->ver_minor, cmd);
                err = -EINVAL;
        }

        /* Fill in the kernel version. */
        param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
        param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;

        return err;
}

/*
 * Copy parameter control struct, including a possible path allocated
 * at the end of the struct.
 */
static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
{
        struct autofs_dev_ioctl tmp, *ads;

        if (copy_from_user(&tmp, in, sizeof(tmp)))
                return ERR_PTR(-EFAULT);

        if (tmp.size < sizeof(tmp))
                return ERR_PTR(-EINVAL);

        ads = kmalloc(tmp.size, GFP_KERNEL);
        if (!ads)
                return ERR_PTR(-ENOMEM);

        if (copy_from_user(ads, in, tmp.size)) {
                kfree(ads);
                return ERR_PTR(-EFAULT);
        }

        return ads;
}

static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
{
        kfree(param);
        return;
}

/*
 * Check sanity of parameter control fields and if a path is present
 * check that it has a "/" and is terminated.
 */
static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
{
        int err = -EINVAL;

        if (check_dev_ioctl_version(cmd, param)) {
                AUTOFS_WARN("invalid device control module version "
                     "supplied for cmd(0x%08x)", cmd);
                goto out;
        }

        if (param->size > sizeof(*param)) {
                err = check_name(param->path);
                if (err) {
                        AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
                                    cmd);
                        goto out;
                }

                err = invalid_str(param->path,
                                 (void *) ((size_t) param + param->size));
                if (err) {
                        AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
                                    cmd);
                        goto out;
                }
        }

        err = 0;
out:
        return err;
}

/*
 * Get the autofs super block info struct from the file opened on
 * the autofs mount point.
 */
static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
{
        struct autofs_sb_info *sbi = NULL;
        struct inode *inode;

        if (f) {
                inode = f->f_path.dentry->d_inode;
                sbi = autofs4_sbi(inode->i_sb);
        }
        return sbi;
}

/* Return autofs module protocol version */
static int autofs_dev_ioctl_protover(struct file *fp,
                                     struct autofs_sb_info *sbi,
                                     struct autofs_dev_ioctl *param)
{
        param->arg1 = sbi->version;
        return 0;
}

/* Return autofs module protocol sub version */
static int autofs_dev_ioctl_protosubver(struct file *fp,
                                        struct autofs_sb_info *sbi,
                                        struct autofs_dev_ioctl *param)
{
        param->arg1 = sbi->sub_version;
        return 0;
}

/*
 * Walk down the mount stack looking for an autofs mount that
 * has the requested device number (aka. new_encode_dev(sb->s_dev).
 */
static int autofs_dev_ioctl_find_super(struct nameidata *nd, dev_t devno)
{
        struct dentry *dentry;
        struct inode *inode;
        struct super_block *sb;
        dev_t s_dev;
        unsigned int err;

        err = -ENOENT;

        /* Lookup the dentry name at the base of our mount point */
        dentry = d_lookup(nd->path.dentry, &nd->last);
        if (!dentry)
                goto out;

        dput(nd->path.dentry);
        nd->path.dentry = dentry;

        /* And follow the mount stack looking for our autofs mount */
        while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
                inode = nd->path.dentry->d_inode;
                if (!inode)
                        break;

                sb = inode->i_sb;
                s_dev = new_encode_dev(sb->s_dev);
                if (devno == s_dev) {
                        if (sb->s_magic == AUTOFS_SUPER_MAGIC) {
                                err = 0;
                                break;
                        }
                }
        }
out:
        return err;
}

/*
 * Walk down the mount stack looking for an autofs mount that
 * has the requested mount type (ie. indirect, direct or offset).
 */
static int autofs_dev_ioctl_find_sbi_type(struct nameidata *nd, unsigned int type)
{
        struct dentry *dentry;
        struct autofs_info *ino;
        unsigned int err;

        err = -ENOENT;

        /* Lookup the dentry name at the base of our mount point */
        dentry = d_lookup(nd->path.dentry, &nd->last);
        if (!dentry)
                goto out;

        dput(nd->path.dentry);
        nd->path.dentry = dentry;

        /* And follow the mount stack looking for our autofs mount */
        while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
                ino = autofs4_dentry_ino(nd->path.dentry);
                if (ino && ino->sbi->type & type) {
                        err = 0;
                        break;
                }
        }
out:
        return err;
}

static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
{
        struct files_struct *files = current->files;
        struct fdtable *fdt;

        spin_lock(&files->file_lock);
        fdt = files_fdtable(files);
        BUG_ON(fdt->fd[fd] != NULL);
        rcu_assign_pointer(fdt->fd[fd], file);
        FD_SET(fd, fdt->close_on_exec);
        spin_unlock(&files->file_lock);
}


/*
 * Open a file descriptor on the autofs mount point corresponding
 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
 */
static int autofs_dev_ioctl_open_mountpoint(const char *path, dev_t devid)
{
        struct file *filp;
        struct nameidata nd;
        int err, fd;

        fd = get_unused_fd();
        if (likely(fd >= 0)) {
                /* Get nameidata of the parent directory */
                err = path_lookup(path, LOOKUP_PARENT, &nd);
                if (err)
                        goto out;

                /*
                 * Search down, within the parent, looking for an
                 * autofs super block that has the device number
                 * corresponding to the autofs fs we want to open.
                 */
                err = autofs_dev_ioctl_find_super(&nd, devid);
                if (err) {
                        path_put(&nd.path);
                        goto out;
                }

                filp = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY,
                                   current_cred());
                if (IS_ERR(filp)) {
                        err = PTR_ERR(filp);
                        goto out;
                }

                autofs_dev_ioctl_fd_install(fd, filp);
        }

        return fd;

out:
        put_unused_fd(fd);
        return err;
}

/* Open a file descriptor on an autofs mount point */
static int autofs_dev_ioctl_openmount(struct file *fp,
                                      struct autofs_sb_info *sbi,
                                      struct autofs_dev_ioctl *param)
{
        const char *path;
        dev_t devid;
        int err, fd;

        /* param->path has already been checked */
        if (!param->arg1)
                return -EINVAL;

        param->ioctlfd = -1;

        path = param->path;
        devid = param->arg1;

        err = 0;
        fd = autofs_dev_ioctl_open_mountpoint(path, devid);
        if (unlikely(fd < 0)) {
                err = fd;
                goto out;
        }

        param->ioctlfd = fd;
out:
        return err;
}

/* Close file descriptor allocated above (user can also use close(2)). */
static int autofs_dev_ioctl_closemount(struct file *fp,
                                       struct autofs_sb_info *sbi,
                                       struct autofs_dev_ioctl *param)
{
        return sys_close(param->ioctlfd);
}

/*
 * Send "ready" status for an existing wait (either a mount or an expire
 * request).
 */
static int autofs_dev_ioctl_ready(struct file *fp,
                                  struct autofs_sb_info *sbi,
                                  struct autofs_dev_ioctl *param)
{
        autofs_wqt_t token;

        token = (autofs_wqt_t) param->arg1;
        return autofs4_wait_release(sbi, token, 0);
}

/*
 * Send "fail" status for an existing wait (either a mount or an expire
 * request).
 */
static int autofs_dev_ioctl_fail(struct file *fp,
                                 struct autofs_sb_info *sbi,
                                 struct autofs_dev_ioctl *param)
{
        autofs_wqt_t token;
        int status;

        token = (autofs_wqt_t) param->arg1;
        status = param->arg2 ? param->arg2 : -ENOENT;
        return autofs4_wait_release(sbi, token, status);
}

/*
 * Set the pipe fd for kernel communication to the daemon.
 *
 * Normally this is set at mount using an option but if we
 * are reconnecting to a busy mount then we need to use this
 * to tell the autofs mount about the new kernel pipe fd. In
 * order to protect mounts against incorrectly setting the
 * pipefd we also require that the autofs mount be catatonic.
 *
 * This also sets the process group id used to identify the
 * controlling process (eg. the owning automount(8) daemon).
 */
static int autofs_dev_ioctl_setpipefd(struct file *fp,
                                      struct autofs_sb_info *sbi,
                                      struct autofs_dev_ioctl *param)
{
        int pipefd;
        int err = 0;

        if (param->arg1 == -1)
                return -EINVAL;

        pipefd = param->arg1;

        mutex_lock(&sbi->wq_mutex);
        if (!sbi->catatonic) {
                mutex_unlock(&sbi->wq_mutex);
                return -EBUSY;
        } else {
                struct file *pipe = fget(pipefd);
                if (!pipe->f_op || !pipe->f_op->write) {
                        err = -EPIPE;
                        fput(pipe);
                        goto out;
                }
                sbi->oz_pgrp = task_pgrp_nr(current);
                sbi->pipefd = pipefd;
                sbi->pipe = pipe;
                sbi->catatonic = 0;
        }
out:
        mutex_unlock(&sbi->wq_mutex);
        return err;
}

/*
 * Make the autofs mount point catatonic, no longer responsive to
 * mount requests. Also closes the kernel pipe file descriptor.
 */
static int autofs_dev_ioctl_catatonic(struct file *fp,
                                      struct autofs_sb_info *sbi,
                                      struct autofs_dev_ioctl *param)
{
        autofs4_catatonic_mode(sbi);
        return 0;
}

/* Set the autofs mount timeout */
static int autofs_dev_ioctl_timeout(struct file *fp,
                                    struct autofs_sb_info *sbi,
                                    struct autofs_dev_ioctl *param)
{
        unsigned long timeout;

        timeout = param->arg1;
        param->arg1 = sbi->exp_timeout / HZ;
        sbi->exp_timeout = timeout * HZ;
        return 0;
}

/*
 * Return the uid and gid of the last request for the mount
 *
 * When reconstructing an autofs mount tree with active mounts
 * we need to re-connect to mounts that may have used the original
 * process uid and gid (or string variations of them) for mount
 * lookups within the map entry.
 */
static int autofs_dev_ioctl_requester(struct file *fp,
                                      struct autofs_sb_info *sbi,
                                      struct autofs_dev_ioctl *param)
{
        struct autofs_info *ino;
        struct nameidata nd;
        const char *path;
        dev_t devid;
        int err = -ENOENT;

        if (param->size <= sizeof(*param)) {
                err = -EINVAL;
                goto out;
        }

        path = param->path;
        devid = sbi->sb->s_dev;

        param->arg1 = param->arg2 = -1;

        /* Get nameidata of the parent directory */
        err = path_lookup(path, LOOKUP_PARENT, &nd);
        if (err)
                goto out;

        err = autofs_dev_ioctl_find_super(&nd, devid);
        if (err)
                goto out_release;

        ino = autofs4_dentry_ino(nd.path.dentry);
        if (ino) {
                err = 0;
                autofs4_expire_wait(nd.path.dentry);
                spin_lock(&sbi->fs_lock);
                param->arg1 = ino->uid;
                param->arg2 = ino->gid;
                spin_unlock(&sbi->fs_lock);
        }

out_release:
        path_put(&nd.path);
out:
        return err;
}

/*
 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
 * more that can be done.
 */
static int autofs_dev_ioctl_expire(struct file *fp,
                                   struct autofs_sb_info *sbi,
                                   struct autofs_dev_ioctl *param)
{
        struct dentry *dentry;
        struct vfsmount *mnt;
        int err = -EAGAIN;
        int how;

        how = param->arg1;
        mnt = fp->f_path.mnt;

        if (sbi->type & AUTOFS_TYPE_TRIGGER)
                dentry = autofs4_expire_direct(sbi->sb, mnt, sbi, how);
        else
                dentry = autofs4_expire_indirect(sbi->sb, mnt, sbi, how);

        if (dentry) {
                struct autofs_info *ino = autofs4_dentry_ino(dentry);

                /*
                 * This is synchronous because it makes the daemon a
                 * little easier
                */
                err = autofs4_wait(sbi, dentry, NFY_EXPIRE);

                spin_lock(&sbi->fs_lock);
                if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
                        ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
                        sbi->sb->s_root->d_mounted++;
                }
                ino->flags &= ~AUTOFS_INF_EXPIRING;
                complete_all(&ino->expire_complete);
                spin_unlock(&sbi->fs_lock);
                dput(dentry);
        }

        return err;
}

/* Check if autofs mount point is in use */
static int autofs_dev_ioctl_askumount(struct file *fp,
                                      struct autofs_sb_info *sbi,
                                      struct autofs_dev_ioctl *param)
{
        param->arg1 = 0;
        if (may_umount(fp->f_path.mnt))
                param->arg1 = 1;
        return 0;
}

/*
 * Check if the given path is a mountpoint.
 *
 * If we are supplied with the file descriptor of an autofs
 * mount we're looking for a specific mount. In this case
 * the path is considered a mountpoint if it is itself a
 * mountpoint or contains a mount, such as a multi-mount
 * without a root mount. In this case we return 1 if the
 * path is a mount point and the super magic of the covering
 * mount if there is one or 0 if it isn't a mountpoint.
 *
 * If we aren't supplied with a file descriptor then we
 * lookup the nameidata of the path and check if it is the
 * root of a mount. If a type is given we are looking for
 * a particular autofs mount and if we don't find a match
 * we return fail. If the located nameidata path is the
 * root of a mount we return 1 along with the super magic
 * of the mount or 0 otherwise.
 *
 * In both cases the the device number (as returned by
 * new_encode_dev()) is also returned.
 */
static int autofs_dev_ioctl_ismountpoint(struct file *fp,
                                         struct autofs_sb_info *sbi,
                                         struct autofs_dev_ioctl *param)
{
        struct nameidata nd;
        const char *path;
        unsigned int type;
        int err = -ENOENT;

        if (param->size <= sizeof(*param)) {
                err = -EINVAL;
                goto out;
        }

        path = param->path;
        type = param->arg1;

        param->arg1 = 0;
        param->arg2 = 0;

        if (!fp || param->ioctlfd == -1) {
                if (type == AUTOFS_TYPE_ANY) {
                        struct super_block *sb;

                        err = path_lookup(path, LOOKUP_FOLLOW, &nd);
                        if (err)
                                goto out;

                        sb = nd.path.dentry->d_sb;
                        param->arg1 = new_encode_dev(sb->s_dev);
                } else {
                        struct autofs_info *ino;

                        err = path_lookup(path, LOOKUP_PARENT, &nd);
                        if (err)
                                goto out;

                        err = autofs_dev_ioctl_find_sbi_type(&nd, type);
                        if (err)
                                goto out_release;

                        ino = autofs4_dentry_ino(nd.path.dentry);
                        param->arg1 = autofs4_get_dev(ino->sbi);
                }

                err = 0;
                if (nd.path.dentry->d_inode &&
                    nd.path.mnt->mnt_root == nd.path.dentry) {
                        err = 1;
                        param->arg2 = nd.path.dentry->d_inode->i_sb->s_magic;
                }
        } else {
                dev_t devid = new_encode_dev(sbi->sb->s_dev);

                err = path_lookup(path, LOOKUP_PARENT, &nd);
                if (err)
                        goto out;

                err = autofs_dev_ioctl_find_super(&nd, devid);
                if (err)
                        goto out_release;

                param->arg1 = autofs4_get_dev(sbi);

                err = have_submounts(nd.path.dentry);

                if (nd.path.mnt->mnt_mountpoint != nd.path.mnt->mnt_root) {
                        if (follow_down(&nd.path.mnt, &nd.path.dentry)) {
                                struct inode *inode = nd.path.dentry->d_inode;
                                param->arg2 = inode->i_sb->s_magic;
                        }
                }
        }

out_release:
        path_put(&nd.path);
out:
        return err;
}

/*
 * Our range of ioctl numbers isn't 0 based so we need to shift
 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
 * lookup.
 */
#define cmd_idx(cmd)    (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))

static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
{
        static struct {
                int cmd;
                ioctl_fn fn;
        } _ioctls[] = {
                {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
                {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
                         autofs_dev_ioctl_protover},
                {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
                         autofs_dev_ioctl_protosubver},
                {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
                         autofs_dev_ioctl_openmount},
                {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
                         autofs_dev_ioctl_closemount},
                {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
                         autofs_dev_ioctl_ready},
                {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
                         autofs_dev_ioctl_fail},
                {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
                         autofs_dev_ioctl_setpipefd},
                {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
                         autofs_dev_ioctl_catatonic},
                {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
                         autofs_dev_ioctl_timeout},
                {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
                         autofs_dev_ioctl_requester},
                {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
                         autofs_dev_ioctl_expire},
                {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
                         autofs_dev_ioctl_askumount},
                {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
                         autofs_dev_ioctl_ismountpoint}
        };
        unsigned int idx = cmd_idx(cmd);

        return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
}

/* ioctl dispatcher */
static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
{
        struct autofs_dev_ioctl *param;
        struct file *fp;
        struct autofs_sb_info *sbi;
        unsigned int cmd_first, cmd;
        ioctl_fn fn = NULL;
        int err = 0;

        /* only root can play with this */
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
        cmd = _IOC_NR(command);

        if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
            cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
                return -ENOTTY;
        }

        /* Copy the parameters into kernel space. */
        param = copy_dev_ioctl(user);
        if (IS_ERR(param))
                return PTR_ERR(param);

        err = validate_dev_ioctl(command, param);
        if (err)
                goto out;

        /* The validate routine above always sets the version */
        if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
                goto done;

        fn = lookup_dev_ioctl(cmd);
        if (!fn) {
                AUTOFS_WARN("unknown command 0x%08x", command);
                return -ENOTTY;
        }

        fp = NULL;
        sbi = NULL;

        /*
         * For obvious reasons the openmount can't have a file
         * descriptor yet. We don't take a reference to the
         * file during close to allow for immediate release.
         */
        if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
            cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
                fp = fget(param->ioctlfd);
                if (!fp) {
                        if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
                                goto cont;
                        err = -EBADF;
                        goto out;
                }

                if (!fp->f_op) {
                        err = -ENOTTY;
                        fput(fp);
                        goto out;
                }

                sbi = autofs_dev_ioctl_sbi(fp);
                if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
                        err = -EINVAL;
                        fput(fp);
                        goto out;
                }

                /*
                 * Admin needs to be able to set the mount catatonic in
                 * order to be able to perform the re-open.
                 */
                if (!autofs4_oz_mode(sbi) &&
                    cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
                        err = -EACCES;
                        fput(fp);
                        goto out;
                }
        }
cont:
        err = fn(fp, sbi, param);

        if (fp)
                fput(fp);
done:
        if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
                err = -EFAULT;
out:
        free_dev_ioctl(param);
        return err;
}

static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
{
        int err;
        err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
        return (long) err;
}

#ifdef CONFIG_COMPAT
static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
{
        return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
}
#else
#define autofs_dev_ioctl_compat NULL
#endif

static const struct file_operations _dev_ioctl_fops = {
        .unlocked_ioctl  = autofs_dev_ioctl,
        .compat_ioctl = autofs_dev_ioctl_compat,
        .owner   = THIS_MODULE,
};

static struct miscdevice _autofs_dev_ioctl_misc = {
        .minor          = MISC_DYNAMIC_MINOR,
        .name           = AUTOFS_DEVICE_NAME,
        .fops           = &_dev_ioctl_fops
};

/* Register/deregister misc character device */
int autofs_dev_ioctl_init(void)
{
        int r;

        r = misc_register(&_autofs_dev_ioctl_misc);
        if (r) {
                AUTOFS_ERROR("misc_register failed for control device");
                return r;
        }

        return 0;
}

void autofs_dev_ioctl_exit(void)
{
        misc_deregister(&_autofs_dev_ioctl_misc);
        return;
}