mirror of
https://github.com/torvalds/linux.git
synced 2024-10-30 16:51:45 +00:00
2a109f2a41
process 1: process 2:
configfs_mkdir("A")
attach_group("A")
attach_item("A")
d_instantiate("A")
populate_groups("A")
mutex_lock("A")
attach_group("A/B")
attach_item("A")
d_instantiate("A/B")
mkdir("A/B/C")
do_path_lookup("A/B/C", LOOKUP_PARENT)
ok
lookup_create("A/B/C")
mutex_lock("A/B")
ok
configfs_mkdir("A/B/C")
ok
attach_group("A/C")
attach_item("A/C")
d_instantiate("A/C")
populate_groups("A/C")
mutex_lock("A/C")
attach_group("A/C/D")
attach_item("A/C/D")
failure
mutex_unlock("A/C")
detach_groups("A/C")
nothing to do
mkdir("A/C/E")
do_path_lookup("A/C/E", LOOKUP_PARENT)
ok
lookup_create("A/C/E")
mutex_lock("A/C")
ok
configfs_mkdir("A/C/E")
ok
detach_item("A/C")
d_delete("A/C")
mutex_unlock("A")
detach_groups("A")
mutex_lock("A/B")
detach_group("A/B")
detach_groups("A/B")
nothing since no _default_ group
detach_item("A/B")
mutex_unlock("A/B")
d_delete("A/B")
detach_item("A")
d_delete("A")
Two bugs:
1/ "A/B/C" and "A/C/E" are created, but never removed while their parent are
removed in the end. The same could happen with symlink() instead of mkdir().
2/ "A" and "A/C" inodes are not locked while detach_item() is called on them,
which may probably confuse VFS.
This commit fixes 1/, tagging new directories with CONFIGFS_USET_CREATING before
building the inode and instantiating the dentry, and validating the whole
group+default groups hierarchy in a second pass by clearing
CONFIGFS_USET_CREATING.
mkdir(), symlink(), lookup(), and dir_open() simply return -ENOENT if
called in (or linking to) a directory tagged with CONFIGFS_USET_CREATING. This
does not prevent userspace from calling stat() successfuly on such directories,
but this prevents userspace from adding (children to | symlinking from/to |
read/write attributes of | listing the contents of) not validated items. In
other words, userspace will not interact with the subsystem on a new item until
the new item creation completes correctly.
It was first proposed to re-use CONFIGFS_USET_IN_MKDIR instead of a new
flag CONFIGFS_USET_CREATING, but this generated conflicts when checking the
target of a new symlink: a valid target directory in the middle of attaching
a new user-created child item could be wrongly detected as being attached.
2/ is fixed by next commit.
Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
158 lines
4.9 KiB
C
158 lines
4.9 KiB
C
/* -*- mode: c; c-basic-offset:8; -*-
|
|
* vim: noexpandtab sw=8 ts=8 sts=0:
|
|
*
|
|
* configfs_internal.h - Internal stuff for configfs
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2 of the License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public
|
|
* License along with this program; if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
|
|
* Boston, MA 021110-1307, USA.
|
|
*
|
|
* Based on sysfs:
|
|
* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
|
|
*
|
|
* configfs Copyright (C) 2005 Oracle. All rights reserved.
|
|
*/
|
|
|
|
#include <linux/slab.h>
|
|
#include <linux/list.h>
|
|
#include <linux/spinlock.h>
|
|
|
|
struct configfs_dirent {
|
|
atomic_t s_count;
|
|
int s_dependent_count;
|
|
struct list_head s_sibling;
|
|
struct list_head s_children;
|
|
struct list_head s_links;
|
|
void * s_element;
|
|
int s_type;
|
|
umode_t s_mode;
|
|
struct dentry * s_dentry;
|
|
struct iattr * s_iattr;
|
|
};
|
|
|
|
#define CONFIGFS_ROOT 0x0001
|
|
#define CONFIGFS_DIR 0x0002
|
|
#define CONFIGFS_ITEM_ATTR 0x0004
|
|
#define CONFIGFS_ITEM_LINK 0x0020
|
|
#define CONFIGFS_USET_DIR 0x0040
|
|
#define CONFIGFS_USET_DEFAULT 0x0080
|
|
#define CONFIGFS_USET_DROPPING 0x0100
|
|
#define CONFIGFS_USET_IN_MKDIR 0x0200
|
|
#define CONFIGFS_USET_CREATING 0x0400
|
|
#define CONFIGFS_NOT_PINNED (CONFIGFS_ITEM_ATTR)
|
|
|
|
extern struct mutex configfs_symlink_mutex;
|
|
extern spinlock_t configfs_dirent_lock;
|
|
|
|
extern struct vfsmount * configfs_mount;
|
|
extern struct kmem_cache *configfs_dir_cachep;
|
|
|
|
extern int configfs_is_root(struct config_item *item);
|
|
|
|
extern struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent *);
|
|
extern int configfs_create(struct dentry *, int mode, int (*init)(struct inode *));
|
|
extern int configfs_inode_init(void);
|
|
extern void configfs_inode_exit(void);
|
|
|
|
extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
|
|
extern int configfs_make_dirent(struct configfs_dirent *,
|
|
struct dentry *, void *, umode_t, int);
|
|
extern int configfs_dirent_is_ready(struct configfs_dirent *);
|
|
|
|
extern int configfs_add_file(struct dentry *, const struct configfs_attribute *, int);
|
|
extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
|
|
|
|
extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
|
|
extern void configfs_drop_dentry(struct configfs_dirent *sd, struct dentry *parent);
|
|
extern int configfs_setattr(struct dentry *dentry, struct iattr *iattr);
|
|
|
|
extern int configfs_pin_fs(void);
|
|
extern void configfs_release_fs(void);
|
|
|
|
extern struct rw_semaphore configfs_rename_sem;
|
|
extern struct super_block * configfs_sb;
|
|
extern const struct file_operations configfs_dir_operations;
|
|
extern const struct file_operations configfs_file_operations;
|
|
extern const struct file_operations bin_fops;
|
|
extern const struct inode_operations configfs_dir_inode_operations;
|
|
extern const struct inode_operations configfs_symlink_inode_operations;
|
|
|
|
extern int configfs_symlink(struct inode *dir, struct dentry *dentry,
|
|
const char *symname);
|
|
extern int configfs_unlink(struct inode *dir, struct dentry *dentry);
|
|
|
|
struct configfs_symlink {
|
|
struct list_head sl_list;
|
|
struct config_item *sl_target;
|
|
};
|
|
|
|
extern int configfs_create_link(struct configfs_symlink *sl,
|
|
struct dentry *parent,
|
|
struct dentry *dentry);
|
|
|
|
static inline struct config_item * to_item(struct dentry * dentry)
|
|
{
|
|
struct configfs_dirent * sd = dentry->d_fsdata;
|
|
return ((struct config_item *) sd->s_element);
|
|
}
|
|
|
|
static inline struct configfs_attribute * to_attr(struct dentry * dentry)
|
|
{
|
|
struct configfs_dirent * sd = dentry->d_fsdata;
|
|
return ((struct configfs_attribute *) sd->s_element);
|
|
}
|
|
|
|
static inline struct config_item *configfs_get_config_item(struct dentry *dentry)
|
|
{
|
|
struct config_item * item = NULL;
|
|
|
|
spin_lock(&dcache_lock);
|
|
if (!d_unhashed(dentry)) {
|
|
struct configfs_dirent * sd = dentry->d_fsdata;
|
|
if (sd->s_type & CONFIGFS_ITEM_LINK) {
|
|
struct configfs_symlink * sl = sd->s_element;
|
|
item = config_item_get(sl->sl_target);
|
|
} else
|
|
item = config_item_get(sd->s_element);
|
|
}
|
|
spin_unlock(&dcache_lock);
|
|
|
|
return item;
|
|
}
|
|
|
|
static inline void release_configfs_dirent(struct configfs_dirent * sd)
|
|
{
|
|
if (!(sd->s_type & CONFIGFS_ROOT)) {
|
|
kfree(sd->s_iattr);
|
|
kmem_cache_free(configfs_dir_cachep, sd);
|
|
}
|
|
}
|
|
|
|
static inline struct configfs_dirent * configfs_get(struct configfs_dirent * sd)
|
|
{
|
|
if (sd) {
|
|
WARN_ON(!atomic_read(&sd->s_count));
|
|
atomic_inc(&sd->s_count);
|
|
}
|
|
return sd;
|
|
}
|
|
|
|
static inline void configfs_put(struct configfs_dirent * sd)
|
|
{
|
|
WARN_ON(!atomic_read(&sd->s_count));
|
|
if (atomic_dec_and_test(&sd->s_count))
|
|
release_configfs_dirent(sd);
|
|
}
|
|
|