linux/fs/kernfs/kernfs-internal.h
Tejun Heo db4aad209b kernfs: associate a new kernfs_node with its parent on creation
Once created, a kernfs_node is always destroyed by kernfs_put().
Since ba7443bc65 ("sysfs, kernfs: implement
kernfs_create/destroy_root()"), kernfs_put() depends on kernfs_root()
to locate the ino_ida.  kernfs_root() in turn depends on
kernfs_node->parent being set for !dir nodes.  This means that
kernfs_put() of a !dir node requires its ->parent to be initialized.

This leads to oops when a newly created !dir node is destroyed without
going through kernfs_add_one() or after failing kernfs_add_one()
before ->parent is set.  kernfs_root() invoked from kernfs_put() will
try to dereference NULL parent.

Fix it by moving parent association to kernfs_new_node() from
kernfs_add_one().  kernfs_new_node() now takes @parent instead of
@root and determines the root from the parent and also sets the new
node's parent properly.  @parent parameter is removed from
kernfs_add_one().  As there's no parent when creating the root node,
__kernfs_new_node() which takes @root as before and doesn't set the
parent is used in that case.

This ensures that a kernfs_node in any stage in its life has its
parent associated and thus can be put.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2014-01-17 11:50:07 -08:00

123 lines
3.3 KiB
C

/*
* fs/kernfs/kernfs-internal.h - kernfs internal header file
*
* Copyright (c) 2001-3 Patrick Mochel
* Copyright (c) 2007 SUSE Linux Products GmbH
* Copyright (c) 2007, 2013 Tejun Heo <teheo@suse.de>
*
* This file is released under the GPLv2.
*/
#ifndef __KERNFS_INTERNAL_H
#define __KERNFS_INTERNAL_H
#include <linux/lockdep.h>
#include <linux/fs.h>
#include <linux/mutex.h>
#include <linux/xattr.h>
#include <linux/kernfs.h>
struct kernfs_iattrs {
struct iattr ia_iattr;
void *ia_secdata;
u32 ia_secdata_len;
struct simple_xattrs xattrs;
};
#define KN_DEACTIVATED_BIAS INT_MIN
/* KERNFS_TYPE_MASK and types are defined in include/linux/kernfs.h */
/**
* kernfs_root - find out the kernfs_root a kernfs_node belongs to
* @kn: kernfs_node of interest
*
* Return the kernfs_root @kn belongs to.
*/
static inline struct kernfs_root *kernfs_root(struct kernfs_node *kn)
{
/* if parent exists, it's always a dir; otherwise, @sd is a dir */
if (kn->parent)
kn = kn->parent;
return kn->dir.root;
}
/*
* Context structure to be used while adding/removing nodes.
*/
struct kernfs_addrm_cxt {
struct kernfs_node *removed;
};
/*
* mount.c
*/
struct kernfs_super_info {
/*
* The root associated with this super_block. Each super_block is
* identified by the root and ns it's associated with.
*/
struct kernfs_root *root;
/*
* Each sb is associated with one namespace tag, currently the
* network namespace of the task which mounted this kernfs
* instance. If multiple tags become necessary, make the following
* an array and compare kernfs_node tag against every entry.
*/
const void *ns;
};
#define kernfs_info(SB) ((struct kernfs_super_info *)(SB->s_fs_info))
extern struct kmem_cache *kernfs_node_cache;
/*
* inode.c
*/
struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn);
void kernfs_evict_inode(struct inode *inode);
int kernfs_iop_permission(struct inode *inode, int mask);
int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr);
int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat);
int kernfs_iop_setxattr(struct dentry *dentry, const char *name, const void *value,
size_t size, int flags);
int kernfs_iop_removexattr(struct dentry *dentry, const char *name);
ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf,
size_t size);
ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size);
void kernfs_inode_init(void);
/*
* dir.c
*/
extern struct mutex kernfs_mutex;
extern const struct dentry_operations kernfs_dops;
extern const struct file_operations kernfs_dir_fops;
extern const struct inode_operations kernfs_dir_iops;
struct kernfs_node *kernfs_get_active(struct kernfs_node *kn);
void kernfs_put_active(struct kernfs_node *kn);
void kernfs_addrm_start(struct kernfs_addrm_cxt *acxt);
int kernfs_add_one(struct kernfs_addrm_cxt *acxt, struct kernfs_node *kn);
void kernfs_addrm_finish(struct kernfs_addrm_cxt *acxt);
struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
const char *name, umode_t mode,
unsigned flags);
/*
* file.c
*/
extern const struct file_operations kernfs_file_fops;
void kernfs_unmap_bin_file(struct kernfs_node *kn);
/*
* symlink.c
*/
extern const struct inode_operations kernfs_symlink_iops;
#endif /* __KERNFS_INTERNAL_H */