linux/fs/autofs/root.c
Christian Brauner 4609e1f18e
fs: port ->permission() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:28 +01:00

929 lines
24 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
* Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
* Copyright 2001-2006 Ian Kent <raven@themaw.net>
*/
#include <linux/capability.h>
#include <linux/compat.h>
#include "autofs_i.h"
static int autofs_dir_permission(struct mnt_idmap *, struct inode *, int);
static int autofs_dir_symlink(struct mnt_idmap *, struct inode *,
struct dentry *, const char *);
static int autofs_dir_unlink(struct inode *, struct dentry *);
static int autofs_dir_rmdir(struct inode *, struct dentry *);
static int autofs_dir_mkdir(struct mnt_idmap *, struct inode *,
struct dentry *, umode_t);
static long autofs_root_ioctl(struct file *, unsigned int, unsigned long);
#ifdef CONFIG_COMPAT
static long autofs_root_compat_ioctl(struct file *,
unsigned int, unsigned long);
#endif
static int autofs_dir_open(struct inode *inode, struct file *file);
static struct dentry *autofs_lookup(struct inode *,
struct dentry *, unsigned int);
static struct vfsmount *autofs_d_automount(struct path *);
static int autofs_d_manage(const struct path *, bool);
static void autofs_dentry_release(struct dentry *);
const struct file_operations autofs_root_operations = {
.open = dcache_dir_open,
.release = dcache_dir_close,
.read = generic_read_dir,
.iterate_shared = dcache_readdir,
.llseek = dcache_dir_lseek,
.unlocked_ioctl = autofs_root_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = autofs_root_compat_ioctl,
#endif
};
const struct file_operations autofs_dir_operations = {
.open = autofs_dir_open,
.release = dcache_dir_close,
.read = generic_read_dir,
.iterate_shared = dcache_readdir,
.llseek = dcache_dir_lseek,
};
const struct inode_operations autofs_dir_inode_operations = {
.lookup = autofs_lookup,
.permission = autofs_dir_permission,
.unlink = autofs_dir_unlink,
.symlink = autofs_dir_symlink,
.mkdir = autofs_dir_mkdir,
.rmdir = autofs_dir_rmdir,
};
const struct dentry_operations autofs_dentry_operations = {
.d_automount = autofs_d_automount,
.d_manage = autofs_d_manage,
.d_release = autofs_dentry_release,
};
static void autofs_del_active(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct autofs_info *ino;
ino = autofs_dentry_ino(dentry);
spin_lock(&sbi->lookup_lock);
list_del_init(&ino->active);
spin_unlock(&sbi->lookup_lock);
}
static int autofs_dir_open(struct inode *inode, struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
if (autofs_oz_mode(sbi))
goto out;
/*
* An empty directory in an autofs file system is always a
* mount point. The daemon must have failed to mount this
* during lookup so it doesn't exist. This can happen, for
* example, if user space returns an incorrect status for a
* mount request. Otherwise we're doing a readdir on the
* autofs file system so just let the libfs routines handle
* it.
*/
spin_lock(&sbi->lookup_lock);
if (!path_is_mountpoint(&file->f_path) && autofs_empty(ino)) {
spin_unlock(&sbi->lookup_lock);
return -ENOENT;
}
spin_unlock(&sbi->lookup_lock);
out:
return dcache_dir_open(inode, file);
}
static void autofs_dentry_release(struct dentry *de)
{
struct autofs_info *ino = autofs_dentry_ino(de);
struct autofs_sb_info *sbi = autofs_sbi(de->d_sb);
pr_debug("releasing %p\n", de);
if (!ino)
return;
if (sbi) {
spin_lock(&sbi->lookup_lock);
if (!list_empty(&ino->active))
list_del(&ino->active);
if (!list_empty(&ino->expiring))
list_del(&ino->expiring);
spin_unlock(&sbi->lookup_lock);
}
autofs_free_ino(ino);
}
static struct dentry *autofs_lookup_active(struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct dentry *parent = dentry->d_parent;
const struct qstr *name = &dentry->d_name;
unsigned int len = name->len;
unsigned int hash = name->hash;
const unsigned char *str = name->name;
struct list_head *p, *head;
head = &sbi->active_list;
if (list_empty(head))
return NULL;
spin_lock(&sbi->lookup_lock);
list_for_each(p, head) {
struct autofs_info *ino;
struct dentry *active;
const struct qstr *qstr;
ino = list_entry(p, struct autofs_info, active);
active = ino->dentry;
spin_lock(&active->d_lock);
/* Already gone? */
if ((int) d_count(active) <= 0)
goto next;
qstr = &active->d_name;
if (active->d_name.hash != hash)
goto next;
if (active->d_parent != parent)
goto next;
if (qstr->len != len)
goto next;
if (memcmp(qstr->name, str, len))
goto next;
if (d_unhashed(active)) {
dget_dlock(active);
spin_unlock(&active->d_lock);
spin_unlock(&sbi->lookup_lock);
return active;
}
next:
spin_unlock(&active->d_lock);
}
spin_unlock(&sbi->lookup_lock);
return NULL;
}
static struct dentry *autofs_lookup_expiring(struct dentry *dentry,
bool rcu_walk)
{
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct dentry *parent = dentry->d_parent;
const struct qstr *name = &dentry->d_name;
unsigned int len = name->len;
unsigned int hash = name->hash;
const unsigned char *str = name->name;
struct list_head *p, *head;
head = &sbi->expiring_list;
if (list_empty(head))
return NULL;
spin_lock(&sbi->lookup_lock);
list_for_each(p, head) {
struct autofs_info *ino;
struct dentry *expiring;
const struct qstr *qstr;
if (rcu_walk) {
spin_unlock(&sbi->lookup_lock);
return ERR_PTR(-ECHILD);
}
ino = list_entry(p, struct autofs_info, expiring);
expiring = ino->dentry;
spin_lock(&expiring->d_lock);
/* We've already been dentry_iput or unlinked */
if (d_really_is_negative(expiring))
goto next;
qstr = &expiring->d_name;
if (expiring->d_name.hash != hash)
goto next;
if (expiring->d_parent != parent)
goto next;
if (qstr->len != len)
goto next;
if (memcmp(qstr->name, str, len))
goto next;
if (d_unhashed(expiring)) {
dget_dlock(expiring);
spin_unlock(&expiring->d_lock);
spin_unlock(&sbi->lookup_lock);
return expiring;
}
next:
spin_unlock(&expiring->d_lock);
}
spin_unlock(&sbi->lookup_lock);
return NULL;
}
static int autofs_mount_wait(const struct path *path, bool rcu_walk)
{
struct autofs_sb_info *sbi = autofs_sbi(path->dentry->d_sb);
struct autofs_info *ino = autofs_dentry_ino(path->dentry);
int status = 0;
if (ino->flags & AUTOFS_INF_PENDING) {
if (rcu_walk)
return -ECHILD;
pr_debug("waiting for mount name=%pd\n", path->dentry);
status = autofs_wait(sbi, path, NFY_MOUNT);
pr_debug("mount wait done status=%d\n", status);
ino->last_used = jiffies;
return status;
}
if (!(sbi->flags & AUTOFS_SBI_STRICTEXPIRE))
ino->last_used = jiffies;
return status;
}
static int do_expire_wait(const struct path *path, bool rcu_walk)
{
struct dentry *dentry = path->dentry;
struct dentry *expiring;
expiring = autofs_lookup_expiring(dentry, rcu_walk);
if (IS_ERR(expiring))
return PTR_ERR(expiring);
if (!expiring)
return autofs_expire_wait(path, rcu_walk);
else {
const struct path this = { .mnt = path->mnt, .dentry = expiring };
/*
* If we are racing with expire the request might not
* be quite complete, but the directory has been removed
* so it must have been successful, just wait for it.
*/
autofs_expire_wait(&this, 0);
autofs_del_expiring(expiring);
dput(expiring);
}
return 0;
}
static struct dentry *autofs_mountpoint_changed(struct path *path)
{
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
/* If this is an indirect mount the dentry could have gone away
* and a new one created.
*
* This is unusual and I can't remember the case for which it
* was originally added now. But an example of how this can
* happen is an autofs indirect mount that has the "browse"
* option set and also has the "symlink" option in the autofs
* map entry. In this case the daemon will remove the browse
* directory and create a symlink as the mount leaving the
* struct path stale.
*
* Another not so obvious case is when a mount in an autofs
* indirect mount that uses the "nobrowse" option is being
* expired at the same time as a path walk. If the mount has
* been umounted but the mount point directory seen before
* becoming unhashed (during a lockless path walk) when a stat
* family system call is made the mount won't be re-mounted as
* it should. In this case the mount point that's been removed
* (by the daemon) will be stale and the a new mount point
* dentry created.
*/
if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
struct dentry *parent = dentry->d_parent;
struct autofs_info *ino;
struct dentry *new;
new = d_lookup(parent, &dentry->d_name);
if (!new)
return NULL;
ino = autofs_dentry_ino(new);
ino->last_used = jiffies;
dput(path->dentry);
path->dentry = new;
}
return path->dentry;
}
static struct vfsmount *autofs_d_automount(struct path *path)
{
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
int status;
pr_debug("dentry=%p %pd\n", dentry, dentry);
/* The daemon never triggers a mount. */
if (autofs_oz_mode(sbi))
return NULL;
/*
* If an expire request is pending everyone must wait.
* If the expire fails we're still mounted so continue
* the follow and return. A return of -EAGAIN (which only
* happens with indirect mounts) means the expire completed
* and the directory was removed, so just go ahead and try
* the mount.
*/
status = do_expire_wait(path, 0);
if (status && status != -EAGAIN)
return NULL;
/* Callback to the daemon to perform the mount or wait */
spin_lock(&sbi->fs_lock);
if (ino->flags & AUTOFS_INF_PENDING) {
spin_unlock(&sbi->fs_lock);
status = autofs_mount_wait(path, 0);
if (status)
return ERR_PTR(status);
goto done;
}
/*
* If the dentry is a symlink it's equivalent to a directory
* having path_is_mountpoint() true, so there's no need to call
* back to the daemon.
*/
if (d_really_is_positive(dentry) && d_is_symlink(dentry)) {
spin_unlock(&sbi->fs_lock);
goto done;
}
if (!path_is_mountpoint(path)) {
/*
* It's possible that user space hasn't removed directories
* after umounting a rootless multi-mount, although it
* should. For v5 path_has_submounts() is sufficient to
* handle this because the leaves of the directory tree under
* the mount never trigger mounts themselves (they have an
* autofs trigger mount mounted on them). But v4 pseudo direct
* mounts do need the leaves to trigger mounts. In this case
* we have no choice but to use the autofs_empty() check and
* require user space behave.
*/
if (sbi->version > 4) {
if (path_has_submounts(path)) {
spin_unlock(&sbi->fs_lock);
goto done;
}
} else {
if (!autofs_empty(ino)) {
spin_unlock(&sbi->fs_lock);
goto done;
}
}
ino->flags |= AUTOFS_INF_PENDING;
spin_unlock(&sbi->fs_lock);
status = autofs_mount_wait(path, 0);
spin_lock(&sbi->fs_lock);
ino->flags &= ~AUTOFS_INF_PENDING;
if (status) {
spin_unlock(&sbi->fs_lock);
return ERR_PTR(status);
}
}
spin_unlock(&sbi->fs_lock);
done:
/* Mount succeeded, check if we ended up with a new dentry */
dentry = autofs_mountpoint_changed(path);
if (!dentry)
return ERR_PTR(-ENOENT);
return NULL;
}
static int autofs_d_manage(const struct path *path, bool rcu_walk)
{
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
int status;
pr_debug("dentry=%p %pd\n", dentry, dentry);
/* The daemon never waits. */
if (autofs_oz_mode(sbi)) {
if (!path_is_mountpoint(path))
return -EISDIR;
return 0;
}
/* Wait for pending expires */
if (do_expire_wait(path, rcu_walk) == -ECHILD)
return -ECHILD;
/*
* This dentry may be under construction so wait on mount
* completion.
*/
status = autofs_mount_wait(path, rcu_walk);
if (status)
return status;
if (rcu_walk) {
/* We don't need fs_lock in rcu_walk mode,
* just testing 'AUTOFS_INF_WANT_EXPIRE' is enough.
*
* We only return -EISDIR when certain this isn't
* a mount-trap.
*/
struct inode *inode;
if (ino->flags & AUTOFS_INF_WANT_EXPIRE)
return 0;
if (path_is_mountpoint(path))
return 0;
inode = d_inode_rcu(dentry);
if (inode && S_ISLNK(inode->i_mode))
return -EISDIR;
if (!autofs_empty(ino))
return -EISDIR;
return 0;
}
spin_lock(&sbi->fs_lock);
/*
* If the dentry has been selected for expire while we slept
* on the lock then it might go away. We'll deal with that in
* ->d_automount() and wait on a new mount if the expire
* succeeds or return here if it doesn't (since there's no
* mount to follow with a rootless multi-mount).
*/
if (!(ino->flags & AUTOFS_INF_EXPIRING)) {
/*
* Any needed mounting has been completed and the path
* updated so check if this is a rootless multi-mount so
* we can avoid needless calls ->d_automount() and avoid
* an incorrect ELOOP error return.
*/
if ((!path_is_mountpoint(path) && !autofs_empty(ino)) ||
(d_really_is_positive(dentry) && d_is_symlink(dentry)))
status = -EISDIR;
}
spin_unlock(&sbi->fs_lock);
return status;
}
/* Lookups in the root directory */
static struct dentry *autofs_lookup(struct inode *dir,
struct dentry *dentry, unsigned int flags)
{
struct autofs_sb_info *sbi;
struct autofs_info *ino;
struct dentry *active;
pr_debug("name = %pd\n", dentry);
/* File name too long to exist */
if (dentry->d_name.len > NAME_MAX)
return ERR_PTR(-ENAMETOOLONG);
sbi = autofs_sbi(dir->i_sb);
pr_debug("pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
current->pid, task_pgrp_nr(current),
sbi->flags & AUTOFS_SBI_CATATONIC,
autofs_oz_mode(sbi));
active = autofs_lookup_active(dentry);
if (active)
return active;
else {
/*
* A dentry that is not within the root can never trigger a
* mount operation, unless the directory already exists, so we
* can return fail immediately. The daemon however does need
* to create directories within the file system.
*/
if (!autofs_oz_mode(sbi) && !IS_ROOT(dentry->d_parent))
return ERR_PTR(-ENOENT);
ino = autofs_new_ino(sbi);
if (!ino)
return ERR_PTR(-ENOMEM);
spin_lock(&sbi->lookup_lock);
spin_lock(&dentry->d_lock);
/* Mark entries in the root as mount triggers */
if (IS_ROOT(dentry->d_parent) &&
autofs_type_indirect(sbi->type))
__managed_dentry_set_managed(dentry);
dentry->d_fsdata = ino;
ino->dentry = dentry;
list_add(&ino->active, &sbi->active_list);
spin_unlock(&sbi->lookup_lock);
spin_unlock(&dentry->d_lock);
}
return NULL;
}
static int autofs_dir_permission(struct mnt_idmap *idmap,
struct inode *inode, int mask)
{
if (mask & MAY_WRITE) {
struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
if (!autofs_oz_mode(sbi))
return -EACCES;
/* autofs_oz_mode() needs to allow path walks when the
* autofs mount is catatonic but the state of an autofs
* file system needs to be preserved over restarts.
*/
if (sbi->flags & AUTOFS_SBI_CATATONIC)
return -EACCES;
}
return generic_permission(idmap, inode, mask);
}
static int autofs_dir_symlink(struct mnt_idmap *idmap,
struct inode *dir, struct dentry *dentry,
const char *symname)
{
struct autofs_info *ino = autofs_dentry_ino(dentry);
struct autofs_info *p_ino;
struct inode *inode;
size_t size = strlen(symname);
char *cp;
pr_debug("%s <- %pd\n", symname, dentry);
BUG_ON(!ino);
autofs_clean_ino(ino);
autofs_del_active(dentry);
cp = kmalloc(size + 1, GFP_KERNEL);
if (!cp)
return -ENOMEM;
strcpy(cp, symname);
inode = autofs_get_inode(dir->i_sb, S_IFLNK | 0555);
if (!inode) {
kfree(cp);
return -ENOMEM;
}
inode->i_private = cp;
inode->i_size = size;
d_add(dentry, inode);
dget(dentry);
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count++;
dir->i_mtime = current_time(dir);
return 0;
}
/*
* NOTE!
*
* Normal filesystems would do a "d_delete()" to tell the VFS dcache
* that the file no longer exists. However, doing that means that the
* VFS layer can turn the dentry into a negative dentry. We don't want
* this, because the unlink is probably the result of an expire.
* We simply d_drop it and add it to a expiring list in the super block,
* which allows the dentry lookup to check for an incomplete expire.
*
* If a process is blocked on the dentry waiting for the expire to finish,
* it will invalidate the dentry and try to mount with a new one.
*
* Also see autofs_dir_rmdir()..
*/
static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
struct autofs_info *p_ino;
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count--;
dput(ino->dentry);
d_inode(dentry)->i_size = 0;
clear_nlink(d_inode(dentry));
dir->i_mtime = current_time(dir);
spin_lock(&sbi->lookup_lock);
__autofs_add_expiring(dentry);
d_drop(dentry);
spin_unlock(&sbi->lookup_lock);
return 0;
}
/*
* Version 4 of autofs provides a pseudo direct mount implementation
* that relies on directories at the leaves of a directory tree under
* an indirect mount to trigger mounts. To allow for this we need to
* set the DMANAGED_AUTOMOUNT and DMANAGED_TRANSIT flags on the leaves
* of the directory tree. There is no need to clear the automount flag
* following a mount or restore it after an expire because these mounts
* are always covered. However, it is necessary to ensure that these
* flags are clear on non-empty directories to avoid unnecessary calls
* during path walks.
*/
static void autofs_set_leaf_automount_flags(struct dentry *dentry)
{
struct dentry *parent;
/* root and dentrys in the root are already handled */
if (IS_ROOT(dentry->d_parent))
return;
managed_dentry_set_managed(dentry);
parent = dentry->d_parent;
/* only consider parents below dentrys in the root */
if (IS_ROOT(parent->d_parent))
return;
managed_dentry_clear_managed(parent);
}
static void autofs_clear_leaf_automount_flags(struct dentry *dentry)
{
struct dentry *parent;
/* flags for dentrys in the root are handled elsewhere */
if (IS_ROOT(dentry->d_parent))
return;
managed_dentry_clear_managed(dentry);
parent = dentry->d_parent;
/* only consider parents below dentrys in the root */
if (IS_ROOT(parent->d_parent))
return;
if (autofs_dentry_ino(parent)->count == 2)
managed_dentry_set_managed(parent);
}
static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
{
struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
struct autofs_info *p_ino;
pr_debug("dentry %p, removing %pd\n", dentry, dentry);
if (ino->count != 1)
return -ENOTEMPTY;
spin_lock(&sbi->lookup_lock);
__autofs_add_expiring(dentry);
d_drop(dentry);
spin_unlock(&sbi->lookup_lock);
if (sbi->version < 5)
autofs_clear_leaf_automount_flags(dentry);
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count--;
dput(ino->dentry);
d_inode(dentry)->i_size = 0;
clear_nlink(d_inode(dentry));
if (dir->i_nlink)
drop_nlink(dir);
return 0;
}
static int autofs_dir_mkdir(struct mnt_idmap *idmap,
struct inode *dir, struct dentry *dentry,
umode_t mode)
{
struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
struct autofs_info *p_ino;
struct inode *inode;
pr_debug("dentry %p, creating %pd\n", dentry, dentry);
BUG_ON(!ino);
autofs_clean_ino(ino);
autofs_del_active(dentry);
inode = autofs_get_inode(dir->i_sb, S_IFDIR | mode);
if (!inode)
return -ENOMEM;
d_add(dentry, inode);
if (sbi->version < 5)
autofs_set_leaf_automount_flags(dentry);
dget(dentry);
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count++;
inc_nlink(dir);
dir->i_mtime = current_time(dir);
return 0;
}
/* Get/set timeout ioctl() operation */
#ifdef CONFIG_COMPAT
static inline int autofs_compat_get_set_timeout(struct autofs_sb_info *sbi,
compat_ulong_t __user *p)
{
unsigned long ntimeout;
int rv;
rv = get_user(ntimeout, p);
if (rv)
goto error;
rv = put_user(sbi->exp_timeout/HZ, p);
if (rv)
goto error;
if (ntimeout > UINT_MAX/HZ)
sbi->exp_timeout = 0;
else
sbi->exp_timeout = ntimeout * HZ;
return 0;
error:
return rv;
}
#endif
static inline int autofs_get_set_timeout(struct autofs_sb_info *sbi,
unsigned long __user *p)
{
unsigned long ntimeout;
int rv;
rv = get_user(ntimeout, p);
if (rv)
goto error;
rv = put_user(sbi->exp_timeout/HZ, p);
if (rv)
goto error;
if (ntimeout > ULONG_MAX/HZ)
sbi->exp_timeout = 0;
else
sbi->exp_timeout = ntimeout * HZ;
return 0;
error:
return rv;
}
/* Return protocol version */
static inline int autofs_get_protover(struct autofs_sb_info *sbi,
int __user *p)
{
return put_user(sbi->version, p);
}
/* Return protocol sub version */
static inline int autofs_get_protosubver(struct autofs_sb_info *sbi,
int __user *p)
{
return put_user(sbi->sub_version, p);
}
/*
* Tells the daemon whether it can umount the autofs mount.
*/
static inline int autofs_ask_umount(struct vfsmount *mnt, int __user *p)
{
int status = 0;
if (may_umount(mnt))
status = 1;
pr_debug("may umount %d\n", status);
status = put_user(status, p);
return status;
}
/* Identify autofs_dentries - this is so we can tell if there's
* an extra dentry refcount or not. We only hold a refcount on the
* dentry if its non-negative (ie, d_inode != NULL)
*/
int is_autofs_dentry(struct dentry *dentry)
{
return dentry && d_really_is_positive(dentry) &&
dentry->d_op == &autofs_dentry_operations &&
dentry->d_fsdata != NULL;
}
/*
* ioctl()'s on the root directory is the chief method for the daemon to
* generate kernel reactions
*/
static int autofs_root_ioctl_unlocked(struct inode *inode, struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
void __user *p = (void __user *)arg;
pr_debug("cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
cmd, arg, sbi, task_pgrp_nr(current));
if (_IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
_IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT)
return -ENOTTY;
if (!autofs_oz_mode(sbi) && !capable(CAP_SYS_ADMIN))
return -EPERM;
switch (cmd) {
case AUTOFS_IOC_READY: /* Wait queue: go ahead and retry */
return autofs_wait_release(sbi, (autofs_wqt_t) arg, 0);
case AUTOFS_IOC_FAIL: /* Wait queue: fail with ENOENT */
return autofs_wait_release(sbi, (autofs_wqt_t) arg, -ENOENT);
case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
autofs_catatonic_mode(sbi);
return 0;
case AUTOFS_IOC_PROTOVER: /* Get protocol version */
return autofs_get_protover(sbi, p);
case AUTOFS_IOC_PROTOSUBVER: /* Get protocol sub version */
return autofs_get_protosubver(sbi, p);
case AUTOFS_IOC_SETTIMEOUT:
return autofs_get_set_timeout(sbi, p);
#ifdef CONFIG_COMPAT
case AUTOFS_IOC_SETTIMEOUT32:
return autofs_compat_get_set_timeout(sbi, p);
#endif
case AUTOFS_IOC_ASKUMOUNT:
return autofs_ask_umount(filp->f_path.mnt, p);
/* return a single thing to expire */
case AUTOFS_IOC_EXPIRE:
return autofs_expire_run(inode->i_sb, filp->f_path.mnt, sbi, p);
/* same as above, but can send multiple expires through pipe */
case AUTOFS_IOC_EXPIRE_MULTI:
return autofs_expire_multi(inode->i_sb,
filp->f_path.mnt, sbi, p);
default:
return -EINVAL;
}
}
static long autofs_root_ioctl(struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
return autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
}
#ifdef CONFIG_COMPAT
static long autofs_root_compat_ioctl(struct file *filp,
unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
int ret;
if (cmd == AUTOFS_IOC_READY || cmd == AUTOFS_IOC_FAIL)
ret = autofs_root_ioctl_unlocked(inode, filp, cmd, arg);
else
ret = autofs_root_ioctl_unlocked(inode, filp, cmd,
(unsigned long) compat_ptr(arg));
return ret;
}
#endif