84 lines
1.8 KiB
C
84 lines
1.8 KiB
C
/*
|
|
* fs/sysfs/symlink.c - operations for initializing and mounting sysfs
|
|
*
|
|
* Copyright (c) 2001-3 Patrick Mochel
|
|
* Copyright (c) 2007 SUSE Linux Products GmbH
|
|
* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
|
|
*
|
|
* This file is released under the GPLv2.
|
|
*
|
|
* Please see Documentation/filesystems/sysfs.txt for more information.
|
|
*/
|
|
|
|
#define DEBUG
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/magic.h>
|
|
#include <linux/mount.h>
|
|
#include <linux/init.h>
|
|
#include <linux/user_namespace.h>
|
|
|
|
#include "sysfs.h"
|
|
|
|
static struct kernfs_root *sysfs_root;
|
|
struct kernfs_node *sysfs_root_kn;
|
|
|
|
static struct dentry *sysfs_mount(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name, void *data)
|
|
{
|
|
struct dentry *root;
|
|
void *ns;
|
|
bool new_sb;
|
|
|
|
if (!(flags & MS_KERNMOUNT)) {
|
|
if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
|
|
return ERR_PTR(-EPERM);
|
|
}
|
|
|
|
ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
|
|
root = kernfs_mount_ns(fs_type, flags, sysfs_root,
|
|
SYSFS_MAGIC, &new_sb, ns);
|
|
if (IS_ERR(root) || !new_sb)
|
|
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
|
|
else if (new_sb)
|
|
/* Userspace would break if executables appear on sysfs */
|
|
root->d_sb->s_iflags |= SB_I_NOEXEC;
|
|
|
|
return root;
|
|
}
|
|
|
|
static void sysfs_kill_sb(struct super_block *sb)
|
|
{
|
|
void *ns = (void *)kernfs_super_ns(sb);
|
|
|
|
kernfs_kill_sb(sb);
|
|
kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
|
|
}
|
|
|
|
static struct file_system_type sysfs_fs_type = {
|
|
.name = "sysfs",
|
|
.mount = sysfs_mount,
|
|
.kill_sb = sysfs_kill_sb,
|
|
.fs_flags = FS_USERNS_VISIBLE | FS_USERNS_MOUNT,
|
|
};
|
|
|
|
int __init sysfs_init(void)
|
|
{
|
|
int err;
|
|
|
|
sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
|
|
NULL);
|
|
if (IS_ERR(sysfs_root))
|
|
return PTR_ERR(sysfs_root);
|
|
|
|
sysfs_root_kn = sysfs_root->kn;
|
|
|
|
err = register_filesystem(&sysfs_fs_type);
|
|
if (err) {
|
|
kernfs_destroy_root(sysfs_root);
|
|
return err;
|
|
}
|
|
|
|
return 0;
|
|
}
|