renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-11-20 08:38:24 +08:00
Code

mtd: mtdchar: Do not corrupt backing device of device node inode

Browse Source 
We cannot modify file->f_mapping->backing_dev_info, because it will corrupt
backing device of device node inode, since file->f_mapping is equal to
inode->i_mapping (see __dentry_open() in fs/open.c).

Let's introduce separate inode for MTD device with appropriate backing
device.

[dwmw2: Refactor to keep it all entirely within mtdchar.c; use iget_locked()]

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Kirill A. Shutemov 2010-05-17 16:55:47 +03:00 committed by David Woodhouse
parent 11c93605fa
commit cd874237d9
1 changed files with 87 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
drivers/mtd/mtdchar.c
View File

@ -15,12 +15,15 @@
#include <linux/smp_lock.h>
#include <linux/backing-dev.h>
#include <linux/compat.h>
#include <linux/mount.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/compatmac.h>
#include <asm/uaccess.h>
#define MTD_INODE_FS_MAGIC 0x11307854
static struct vfsmount *mtd_inode_mnt __read_mostly;
/*
* Data structure to hold the pointer to the mtd device as well
@ -28,6 +31,7 @@
*/
struct mtd_file_info {
struct mtd_info *mtd;
struct inode *ino;
enum mtd_file_modes mode;
};
@ -64,6 +68,7 @@ static int mtd_open(struct inode *inode, struct file *file)
int ret = 0;
struct mtd_info *mtd;
struct mtd_file_info *mfi;
struct inode *mtd_ino;
DEBUG(MTD_DEBUG_LEVEL0, "MTD_open\n");
@ -85,11 +90,23 @@ static int mtd_open(struct inode *inode, struct file *file)
goto out;
}
if (mtd->backing_dev_info)
file->f_mapping->backing_dev_info = mtd->backing_dev_info;
mtd_ino = iget_locked(mtd_inode_mnt->mnt_sb, devnum);
if (!mtd_ino) {
put_mtd_device(mtd);
ret = -ENOMEM;
goto out;
}
if (mtd_ino->i_state & I_NEW) {
mtd_ino->i_private = mtd;
mtd_ino->i_mode = S_IFCHR;
mtd_ino->i_data.backing_dev_info = mtd->backing_dev_info;
unlock_new_inode(mtd_ino);
}
file->f_mapping = mtd_ino->i_mapping;
/* You can't open it RW if it's not a writeable device */
if ((file->f_mode & FMODE_WRITE) && !(mtd->flags & MTD_WRITEABLE)) {
iput(mtd_ino);
put_mtd_device(mtd);
ret = -EACCES;
goto out;
@ -97,10 +114,12 @@ static int mtd_open(struct inode *inode, struct file *file)
mfi = kzalloc(sizeof(*mfi), GFP_KERNEL);
if (!mfi) {
iput(mtd_ino);
put_mtd_device(mtd);
ret = -ENOMEM;
goto out;
}
mfi->ino = mtd_ino;
mfi->mtd = mtd;
file->private_data = mfi;
@ -122,6 +141,8 @@ static int mtd_close(struct inode *inode, struct file *file)
if ((file->f_mode & FMODE_WRITE) && mtd->sync)
mtd->sync(mtd);
iput(mfi->ino);
put_mtd_device(mtd);
file->private_data = NULL;
kfree(mfi);
@ -951,22 +972,80 @@ static const struct file_operations mtd_fops = {
#endif
};
static int mtd_inodefs_get_sb(struct file_system_type *fs_type, int flags,
const char *dev_name, void *data,
struct vfsmount *mnt)
{
return get_sb_pseudo(fs_type, "mtd_inode:", NULL, MTD_INODE_FS_MAGIC,
mnt);
}
static struct file_system_type mtd_inodefs_type = {
.name = "mtd_inodefs",
.get_sb = mtd_inodefs_get_sb,
.kill_sb = kill_anon_super,
};
static void mtdchar_notify_add(struct mtd_info *mtd)
{
}
static void mtdchar_notify_remove(struct mtd_info *mtd)
{
struct inode *mtd_ino = ilookup(mtd_inode_mnt->mnt_sb, mtd->index);
if (mtd_ino) {
/* Destroy the inode if it exists */
mtd_ino->i_nlink = 0;
iput(mtd_ino);
}
}
static struct mtd_notifier mtdchar_notifier = {
.add = mtdchar_notify_add,
.remove = mtdchar_notify_remove,
};
static int __init init_mtdchar(void)
{
int status;
int ret;
status = __register_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS,
ret = __register_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS,
"mtd", &mtd_fops);
if (status < 0) {
printk(KERN_NOTICE "Can't allocate major number %d for Memory Technology Devices.\n",
MTD_CHAR_MAJOR);
if (ret < 0) {
pr_notice("Can't allocate major number %d for "
"Memory Technology Devices.\n", MTD_CHAR_MAJOR);
return ret;
}
return status;
ret = register_filesystem(&mtd_inodefs_type);
if (ret) {
pr_notice("Can't register mtd_inodefs filesystem: %d\n", ret);
goto err_unregister_chdev;
}
mtd_inode_mnt = kern_mount(&mtd_inodefs_type);
if (IS_ERR(mtd_inode_mnt)) {
ret = PTR_ERR(mtd_inode_mnt);
pr_notice("Error mounting mtd_inodefs filesystem: %d\n", ret);
goto err_unregister_filesystem;
}
register_mtd_user(&mtdchar_notifier);
return ret;
err_unregister_filesystem:
unregister_filesystem(&mtd_inodefs_type);
err_unregister_chdev:
__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
return ret;
}
static void __exit cleanup_mtdchar(void)
{
unregister_mtd_user(&mtdchar_notifier);
mntput(mtd_inode_mnt);
unregister_filesystem(&mtd_inodefs_type);
__unregister_chrdev(MTD_CHAR_MAJOR, 0, 1 << MINORBITS, "mtd");
}