android_kernel_motorola_sm6225/fs/sysfs/group.c
James Morris 057f6c019f security: prevent permission checking of file removal via sysfs_remove_group()
Prevent permission checking from being performed when the kernel wants to
unconditionally remove a sysfs group, by introducing an kernel-only variant
of lookup_one_len(), lookup_one_len_kern().

Additionally, as sysfs_remove_group() does not check the return value of
the lookup before using it, a BUG_ON has been added to pinpoint the cause
of any problems potentially caused by this (and as a form of annotation).

Signed-off-by: James Morris <jmorris@namei.org>
Cc: Nagendra Singh Tomar <nagendra_tomar@adaptec.com>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2007-04-27 10:57:33 -07:00

90 lines
1.8 KiB
C

/*
* fs/sysfs/group.c - Operations for adding/removing multiple files at once.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Lab
*
* This file is released undert the GPL v2.
*
*/
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <asm/semaphore.h>
#include "sysfs.h"
static void remove_files(struct dentry * dir,
const struct attribute_group * grp)
{
struct attribute *const* attr;
for (attr = grp->attrs; *attr; attr++)
sysfs_hash_and_remove(dir,(*attr)->name);
}
static int create_files(struct dentry * dir,
const struct attribute_group * grp)
{
struct attribute *const* attr;
int error = 0;
for (attr = grp->attrs; *attr && !error; attr++) {
error = sysfs_add_file(dir, *attr, SYSFS_KOBJ_ATTR);
}
if (error)
remove_files(dir,grp);
return error;
}
int sysfs_create_group(struct kobject * kobj,
const struct attribute_group * grp)
{
struct dentry * dir;
int error;
BUG_ON(!kobj || !kobj->dentry);
if (grp->name) {
error = sysfs_create_subdir(kobj,grp->name,&dir);
if (error)
return error;
} else
dir = kobj->dentry;
dir = dget(dir);
if ((error = create_files(dir,grp))) {
if (grp->name)
sysfs_remove_subdir(dir);
}
dput(dir);
return error;
}
void sysfs_remove_group(struct kobject * kobj,
const struct attribute_group * grp)
{
struct dentry * dir;
if (grp->name) {
dir = lookup_one_len_kern(grp->name, kobj->dentry,
strlen(grp->name));
BUG_ON(IS_ERR(dir));
}
else
dir = dget(kobj->dentry);
remove_files(dir,grp);
if (grp->name)
sysfs_remove_subdir(dir);
/* release the ref. taken in this routine */
dput(dir);
}
EXPORT_SYMBOL_GPL(sysfs_create_group);
EXPORT_SYMBOL_GPL(sysfs_remove_group);