Re: Where is ext2/3 secure delete ("s") attribute?

From: Jeff Garzik (jgarzik@pobox.com)
Date: Thu Nov 21 2002 - 23:39:11 EST


Albert D. Cahalan wrote:

> Jeff Garzik writes:
>
> >Albert D. Cahalan wrote:
>
>
> >>Forget the shred program. It's less useful than having the
> >>filesystem simply zero the blocks, because it's slow and you
> >>can't be sure to hit the OS-visible blocks.
> >
> >Why not?
> >
> >Please name a filesystem that moves allocated blocks around on you. And
> >point to code, too.
>
>
> Reiserfs tails
> fs/reiserfs

inodes don't move

> ext3 with data journalling
> fs/ext3

the allocated blocks don't change

> the journalling flash filesystems
> fs/jffs
> fs/jffs2

yep

> NTFS with compression
> fs/ntfs

the allocated blocks don't change

> Multiple overwrites won't protect you from the disk manufacturer
> or the NSA. Only one is needed to protect against root & kernel.
> So it makes sense to have the filesystem zero the blocks when
> they are freed from a file.

if you need to protect against root, then zeroing the blocks isn't going
to help for LVM or jffs or other journalling.

        Jeff

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