/*
* 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;
err = check_dev_ioctl_version(cmd, param);
if (err) {
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;
}
