[PATCH] r/o bind mounts: elevate write count for ioctls()
Some ioctl()s can cause writes to the filesystem. Take these, and make them
use mnt_want/drop_write() instead.
[AV: updated]
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/jfs/ioctl.c b/fs/jfs/ioctl.c
index a1f8e37..afe222b 100644
--- a/fs/jfs/ioctl.c
+++ b/fs/jfs/ioctl.c
@@ -8,6 +8,7 @@
#include <linux/fs.h>
#include <linux/ctype.h>
#include <linux/capability.h>
+#include <linux/mount.h>
#include <linux/time.h>
#include <linux/sched.h>
#include <asm/current.h>
@@ -65,23 +66,30 @@
return put_user(flags, (int __user *) arg);
case JFS_IOC_SETFLAGS: {
unsigned int oldflags;
+ int err;
- if (IS_RDONLY(inode))
- return -EROFS;
+ err = mnt_want_write(filp->f_path.mnt);
+ if (err)
+ return err;
- if (!is_owner_or_cap(inode))
- return -EACCES;
-
- if (get_user(flags, (int __user *) arg))
- return -EFAULT;
+ if (!is_owner_or_cap(inode)) {
+ err = -EACCES;
+ goto setflags_out;
+ }
+ if (get_user(flags, (int __user *) arg)) {
+ err = -EFAULT;
+ goto setflags_out;
+ }
flags = jfs_map_ext2(flags, 1);
if (!S_ISDIR(inode->i_mode))
flags &= ~JFS_DIRSYNC_FL;
/* Is it quota file? Do not allow user to mess with it */
- if (IS_NOQUOTA(inode))
- return -EPERM;
+ if (IS_NOQUOTA(inode)) {
+ err = -EPERM;
+ goto setflags_out;
+ }
/* Lock against other parallel changes of flags */
mutex_lock(&inode->i_mutex);
@@ -98,7 +106,8 @@
(JFS_APPEND_FL | JFS_IMMUTABLE_FL))) {
if (!capable(CAP_LINUX_IMMUTABLE)) {
mutex_unlock(&inode->i_mutex);
- return -EPERM;
+ err = -EPERM;
+ goto setflags_out;
}
}
@@ -110,7 +119,9 @@
mutex_unlock(&inode->i_mutex);
inode->i_ctime = CURRENT_TIME_SEC;
mark_inode_dirty(inode);
- return 0;
+setflags_out:
+ mnt_drop_write(filp->f_path.mnt);
+ return err;
}
default:
return -ENOTTY;
