linux-kernel - Re: [PATCH 0/3] block: sed-opal: add support for shadow MBR done flag and write

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Message-ID: <alpine.LRH.2.21.1905032058110.30331@linux.fjfi.cvut.cz>
Date:   Fri, 3 May 2019 22:32:19 +0200 (CEST)
From:   David Kozub <zub@...ux.fjfi.cvut.cz>
To:     Christoph Hellwig <hch@...radead.org>,
        Scott Bauer <sbauer@...donthack.me>
cc:     Jens Axboe <axboe@...nel.dk>,
        Jonathan Derrick <jonathan.derrick@...el.com>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jonas Rabenstein <jonas.rabenstein@...dium.uni-erlangen.de>
Subject: Re: [PATCH 0/3] block: sed-opal: add support for shadow MBR done
 flag and write

On Wed, 1 May 2019, Christoph Hellwig wrote:

>> I successfully tested toggling the MBR done flag and writing the shadow MBR
>> using some tools I hacked together[4] with a Samsung SSD 850 EVO drive.
>
> Can you submit the tool to util-linux so that we get it into distros?

There is already Scott's sed-opal-temp[1] and a fork by Jonas that adds 
support for older version of these new IOCTLs[2]. There was already some 
discussion of getting that to util-linux.[3]

While I like my hack, sed-opal-temp can do much more (my tool supports 
just the few things I actually use). But there are two things which 
sed-opal-temp currently lacks which my hack has:

* It can use a PBKDF2 hash (salted by disk serial number) of the password
   rather than the password directly. This makes it compatible with sedutil
   and I think it's also better practice (as firmware can contain many
   surprises).

* It contains a 'PBA' (pre-boot authorization) tool. A tool intended to be
   run from shadow mbr that asks for a password and uses it to unlock all
   disks and set shadow mbr done flag, so after restart the computer boots
   into the real OS.

@Scott: What are your plans with sed-opal-temp? If you want I can update 
Jonas' patches to the adapted IOCTLs. What are your thoughts on PW hashing 
and a PBA tool?

Best regards,
David

[1] https://github.com/ScottyBauer/sed-opal-temp
[2] https://github.com/ghostav/sed-opal-temp
[3] https://lkml.org/lkml/2019/2/4/736