/* * 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 & SB_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) root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE; 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_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; }