// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2008 Red Hat, Inc. All rights reserved.
* Copyright 2008 Ian Kent <[email protected]>
*/
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/compat.h>
#include <linux/fdtable.h>
#include <linux/magic.h>
#include <linux/nospec.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 service shutdown.
*/
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, size_t size)
{
if (memchr(str, 0, size))
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 ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
(param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
pr_warn("ioctl control interface version mismatch: "
"kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
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, *res;
if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
return ERR_PTR(-EFAULT);
if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
return ERR_PTR(-EINVAL);
if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
return ERR_PTR(-ENAMETOOLONG);
res = memdup_user(in, tmp.size);
if (!IS_ERR(res))
res->size = tmp.size;
return res;
}
static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
{
kfree(param);
}
/*
* Check sanity of parameter control fields and if a path is present
* check that it is terminated and contains at least one "/".
*/
static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
{
int err;
err = check_dev_ioctl_version(cmd, param);
if (err) {
pr_warn("invalid device control module version "
"supplied for cmd(0x%08x)\n", cmd);
goto out;
}
if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
if (err) {
pr_warn(
"path string terminator missing for cmd(0x%08x)\n",
cmd);
goto out;
}
/* Setting the per-dentry expire timeout requires a trailing
* path component, ie. no '/', so invert the logic of the
* check_name() return for AUTOFS_DEV_IOCTL_TIMEOUT_CMD.
*/
err = check_name(param->path);
if (cmd == AUTOFS_DEV_IOCTL_TIMEOUT_CMD)
err = err ? 0 : -EINVAL;
if (err) {
pr_warn("invalid path supplied for cmd(0x%08x)\n",
cmd);
goto out;
}
} else {
unsigned int inr = _IOC_NR(cmd);
if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
err = -EINVAL;
goto out;
}
}
err = 0;
out:
return err;
}
/* Return autofs dev ioctl version */
static int autofs_dev_ioctl_version(struct file *fp,
struct autofs_sb_info *sbi,
struct autofs_dev_ioctl *param)
{
/* This should have already been set. */
param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
return 0;
}
/* 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->protover.version = 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->protosubver.sub_version = sbi->sub_version;
return 0;
}
/* Find the topmost mount satisfying test() */
static int find_autofs_mount(const char *pathname,
struct path *res,
int test(const struct path *path, void *data),
void *data)
{
struct path path;
int err;
err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
if (err)
return err;
err = -ENOENT;
while (path.dentry == path.mnt->mnt_root) {
if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
if (test(&path, data)) {
path_get(&path);
*res = path;
err = 0;
break;
}
}
if (!follow_up(&path))
break;
}
path_put(&path);
return err;
}
static int test_by_dev(const struct path *path, void *p)
{
return path->dentry->d_sb->s_dev == *(dev_t *)p;
}
static int test_by_type(const struct path *path, void *p)
{
struct autofs_info *ino = autofs_dentry_ino(path->dentry);
return ino && ino->sbi->type & *(unsigned *)p;
}
/*
* 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 *name, dev_t devid)
{
int err, fd;
fd = get_unused_fd_flags(O_CLOEXEC);
if (likely(fd >= 0)) {
struct file *filp;
struct path path;
err = find_autofs_mount(name, &path, test_by_dev, &devid);
if (err)
goto out;
filp = dentry_open(&path, O_RDONLY, current_cred());
path_put(&path);
if (IS_ERR(filp)) {
err = PTR_ERR(filp);
goto out;
}
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 been checked in validate_dev_ioctl() */
if (!param->openmount.devid)
return -EINVAL;
param->ioctlfd = -1;
path = param->path;
devid = new_decode_dev(param->openmount.devid);
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 close_fd(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->ready.token;
return autofs_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->fail.token;
status = param->fail.status < 0 ? param->fail.status : -ENOENT;
return autofs_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;
struct pid *new_pid = NULL;
if (param->setpipefd.pipefd == -1)
return -EINVAL;
pipefd = param->setpipefd.pipefd;
mutex_lock(&sbi->wq_mutex);
if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
mutex_unlock(&sbi->wq_mutex);
return -EBUSY;
} else {
struct file *pipe;
new_pid = get_task_pid(current, PIDTYPE_PGID);
if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
pr_warn("not allowed to change PID namespace\n");
err = -EINVAL;
goto out;
}
pipe = fget(pipefd);
if (!pipe) {
err = -EBADF;
goto out;
}
if (autofs_prepare_pipe(pipe) < 0) {
err = -EPIPE;
fput(pipe);
goto out;
}
swap(sbi->oz_pgrp, new_pid);
sbi->pipefd = pipefd;
sbi->pipe = pipe;
sbi->flags &= ~AUTOFS_SBI_CATATONIC;
}
out:
put_pid(new_pid);
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)
{
autofs_catatonic_mode(sbi);
return 0;
}
/*
* Set the autofs mount expire timeout.
*
* There are two places an expire timeout can be set, in the autofs
* super block info. (this is all that's needed for direct and offset
* mounts because there's a distinct mount corresponding to each of
* these) and per-dentry within within the dentry info. If a per-dentry
* timeout is set it will override the expire timeout set in the parent
* autofs super block info.
*
* If setting the autofs super block expire timeout the autofs_dev_ioctl
* size field will be equal to the autofs_dev_ioctl structure size. If
* setting the per-dentry expire timeout the mount point name is passed
* in the autofs_dev_ioctl path field and the size field updated to
* reflect this.
*
* Setting the autofs mount expire timeout sets the timeout in the super
* block info. struct. Setting the per-dentry timeout does a little more.
* If the timeout is equal to -1 the per-dentry timeout (and flag) is
* cleared which reverts to using the super block timeout, otherwise if
* timeout is 0 the timeout is set to this value and the flag is left
* set which disables expiration for the mount point, lastly the flag
* and the timeout are set enabling the dentry to use this timeout.
*/
static int autofs_dev_ioctl_timeout(struct file *fp,
struct autofs_sb_info *sbi,
struct autofs_dev_ioctl *param)
{
unsigned long timeout = param->timeout.timeout;
/* If setting the expire timeout for an individual indirect
* mount point dentry the mount trailing component path is
* placed in param->path and param->size adjusted to account
* for it otherwise param->size it is set to the structure
* size.
*/
if (param->size == AUTOFS_DEV_IOCTL_SIZE) {
param->timeout.timeout = sbi->exp_timeout / HZ;
sbi->exp_timeout = timeout * HZ;
} else {
struct dentry *base = fp->f_path.dentry;
struct inode *inode = base->d_inode;
int path_len = param->size - AUTOFS_DEV_IOCTL_SIZE - 1;
struct dentry *dentry;
struct autofs_info *ino;
if (!autofs_type_indirect(sbi->type))
return -EINVAL;
/* An expire timeout greater than the superblock timeout
* could be a problem at shutdown but the super block
* timeout itself can change so all we can really do is
* warn the user.
*/
if (timeout >= sbi->exp_timeout)
pr_warn("per-mount expire timeout is greater than "
"the parent autofs mount timeout which could "
"prevent shutdown\n");
inode_lock_shared(inode);
dentry = try_lookup_one_len(param->path, base, path_len);
inode_unlock_shared(inode);
if (IS_ERR_OR_NULL(dentry))
return dentry ? PTR_ERR(dentry) : -ENOENT;
ino = autofs_dentry_ino(dentry);
if (!ino) {
dput(dentry);
return -ENOENT;
}
if (ino->exp_timeout && ino->flags & AUTOFS_INF_EXPIRE_SET)
param->timeout.timeout = ino->exp_timeout / HZ;
else
param->timeout.timeout = sbi->exp_timeout / HZ;
if (timeout == -1) {
/* Revert to using the super block timeout */
ino->flags &= ~AUTOFS_INF_EXPIRE_SET;
ino->exp_timeout = 0;
} else {
/* Set the dentry expire flag and timeout.
*
* If timeout is 0 it will prevent the expire
* of this particular automount.
*/
ino->flags |= AUTOFS_INF_EXPIRE_SET;
ino->exp_timeout = timeout * HZ;
}
dput(dentry);
}
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 path path;
dev_t devid;
int err = -ENOENT;
/* param->path has been checked in validate_dev_ioctl() */
devid = sbi->sb->s_dev;
param->requester.uid = param->requester.gid = -1;
err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
if (err)
goto out;
ino = autofs_dentry_ino(path.dentry);
if (ino) {
err = 0;
autofs_expire_wait(&path, 0);
spin_lock(&sbi->fs_lock);
param->requester.uid =
from_kuid_munged(current_user_ns(), ino->uid);
param->requester.gid =
from_kgid_munged(current_user_ns(), ino->gid);
spin_unlock(&sbi->fs_lock);
}
path_put(&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 vfsmount *mnt;
int how;
how = param->expire.how;
mnt = fp->f_path.mnt;
return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
}
/* 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->askumount.may_umount = 0;
if (may_umount(fp->f_path.mnt))
param->askumount.may_umount = 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 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 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 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 path path;
const char *name;
unsigned int type;
unsigned int devid, magic;
int err = -ENOENT;
/* param->path has been checked in validate_dev_ioctl() */
name = param->path;
type = param->ismountpoint.in.type;
param->ismountpoint.out.devid = devid = 0;
param->ismountpoint.out.magic = magic = 0;
if (!fp || param->ioctlfd == -1) {
if (autofs_type_any(type))
err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
&path);
else
err = find_autofs_mount(name, &path,
test_by_type, &type);
if (err)
goto out;
devid = new_encode_dev(path.dentry->d_sb->s_dev);
err = 0;
if (path.mnt->mnt_root == path.dentry) {
err = 1;
magic = path.dentry->d_sb->s_magic;
}
} else {
dev_t dev = sbi->sb->s_dev;
err = find_autofs_mount(name, &path, test_by_dev, &dev);
if (err)
goto out;
devid = new_encode_dev(dev);
err = path_has_submounts(&path);
if (follow_down_one(&path))
magic = path.dentry->d_sb->s_magic;
}
param->ismountpoint.out.devid = devid;
param->ismountpoint.out.magic = magic;
path_put(&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 const ioctl_fn _ioctls[] = {
autofs_dev_ioctl_version,
autofs_dev_ioctl_protover,
autofs_dev_ioctl_protosubver,
autofs_dev_ioctl_openmount,
autofs_dev_ioctl_closemount,
autofs_dev_ioctl_ready,
autofs_dev_ioctl_fail,
autofs_dev_ioctl_setpipefd,
autofs_dev_ioctl_catatonic,
autofs_dev_ioctl_timeout,
autofs_dev_ioctl_requester,
autofs_dev_ioctl_expire,
autofs_dev_ioctl_askumount,
autofs_dev_ioctl_ismountpoint,
};
unsigned int idx = cmd_idx(cmd);
if (idx >= ARRAY_SIZE(_ioctls))
return NULL;
idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls));
return _ioctls[idx];
}
/* 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;
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;
}
/* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
* and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
*/
if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
/* 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;
fn = lookup_dev_ioctl(cmd);
if (!fn) {
pr_warn("unknown command 0x%08x\n", command);
err = -ENOTTY;
goto out;
}
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,
* and the same for retrieving ioctl version.
*/
if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
struct super_block *sb;
fp = fget(param->ioctlfd);
if (!fp) {
if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
goto cont;
err = -EBADF;
goto out;
}
sb = file_inode(fp)->i_sb;
if (sb->s_type != &autofs_fs_type) {
err = -EINVAL;
fput(fp);
goto out;
}
sbi = autofs_sbi(sb);
/*
* Admin needs to be able to set the mount catatonic in
* order to be able to perform the re-open.
*/
if (!autofs_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);
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, unsigned int command,
unsigned long 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, unsigned int command,
unsigned long u)
{
return autofs_dev_ioctl(file, command, (unsigned long) 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,
.llseek = noop_llseek,
};
static struct miscdevice _autofs_dev_ioctl_misc = {
.minor = AUTOFS_MINOR,
.name = AUTOFS_DEVICE_NAME,
.fops = &_dev_ioctl_fops,
.mode = 0644,
};
MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
MODULE_ALIAS("devname:autofs");
/* Register/deregister misc character device */
int __init autofs_dev_ioctl_init(void)
{
int r;
r = misc_register(&_autofs_dev_ioctl_misc);
if (r) {
pr_err("misc_register failed for control device\n");
return r;
}
return 0;
}
void autofs_dev_ioctl_exit(void)
{
misc_deregister(&_autofs_dev_ioctl_misc);
}
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