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SubjectRe: Where is ext2/3 secure delete ("s") attribute?
Date
Jeff Garzik writes:
> Albert D. Cahalan wrote:
>> Jeff Garzik writes:

>>> Please name a filesystem that moves allocated blocks around
>>> on you. And point to code, too.
>>
>> Reiserfs tails
>> fs/reiserfs
>
> inodes don't move

In that case I suppose you could iterate through all possible
tail sizes. In any case, Reiserfs 4 is coming. Reiserfs 4 shifts
the tree all over.

>> ext3 with data journalling
>> fs/ext3
>
> the allocated blocks don't change

Same effect though: only the filesystem driver can know how
to overwrite a file.

>> the journalling flash filesystems
>> fs/jffs
>> fs/jffs2
>
> yep
>
>> NTFS with compression
>> fs/ntfs
>
> the allocated blocks don't change

They must. I suppose that might not be implemented yet.

>> 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.

By "protect against root" of course I mean a future cracked box
or the drive put into another machine.

LVM has to cooperate. If it can't, then that's a bug. Snapshots
count the same as keeping backups on separate media. Likewise,
fsck and defraggers need to cooperate.
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