From: Mike Snitzer <snitzer@redhat.com>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Satya Tangirala <satyat@google.com>, Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org, linux-block@vger.kernel.org,
dm-devel@redhat.com, Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH 2/3] dm: add support for passing through inline crypto support
Date: Wed, 23 Sep 2020 21:14:39 -0400 [thread overview]
Message-ID: <20200924011438.GD10500@redhat.com> (raw)
In-Reply-To: <20200922003255.GC32959@sol.localdomain>
On Mon, Sep 21 2020 at 8:32pm -0400,
Eric Biggers <ebiggers@kernel.org> wrote:
> On Wed, Sep 09, 2020 at 11:44:21PM +0000, Satya Tangirala wrote:
> > From: Eric Biggers <ebiggers@google.com>
> >
> > Update the device-mapper core to support exposing the inline crypto
> > support of the underlying device(s) through the device-mapper device.
> >
> > This works by creating a "passthrough keyslot manager" for the dm
> > device, which declares support for encryption settings which all
> > underlying devices support. When a supported setting is used, the bio
> > cloning code handles cloning the crypto context to the bios for all the
> > underlying devices. When an unsupported setting is used, the blk-crypto
> > fallback is used as usual.
> >
> > Crypto support on each underlying device is ignored unless the
> > corresponding dm target opts into exposing it. This is needed because
> > for inline crypto to semantically operate on the original bio, the data
> > must not be transformed by the dm target. Thus, targets like dm-linear
> > can expose crypto support of the underlying device, but targets like
> > dm-crypt can't. (dm-crypt could use inline crypto itself, though.)
> >
> > When a key is evicted from the dm device, it is evicted from all
> > underlying devices.
> >
> > Signed-off-by: Eric Biggers <ebiggers@google.com>
> > Co-developed-by: Satya Tangirala <satyat@google.com>
> > Signed-off-by: Satya Tangirala <satyat@google.com>
>
> Looks good as far as Satya's changes from my original patch are concerned.
>
> Can the device-mapper maintainers take a look at this?
In general it looks like these changes were implemented very carefully
and are reasonable if we _really_ want to enable passing through inline
crypto.
I do have concerns about the inability to handle changes at runtime (due
to a table reload that introduces new devices without the encryption
settings the existing devices in the table are using). But the fallback
mechanism saves it from being a complete non-starter.
Can you help me better understand the expected consumer of this code?
If you have something _real_ please be explicit. It makes justifying
supporting niche code like this more tolerable.
Thanks,
Mike
next prev parent reply other threads:[~2020-09-24 1:14 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-09 23:44 [PATCH 0/3] add support for inline encryption to device mapper Satya Tangirala
2020-09-09 23:44 ` [PATCH 1/3] block: keyslot-manager: Introduce passthrough keyslot manager Satya Tangirala
2020-09-22 0:27 ` Eric Biggers
2020-09-09 23:44 ` [PATCH 2/3] dm: add support for passing through inline crypto support Satya Tangirala
2020-09-22 0:32 ` Eric Biggers
2020-09-24 1:14 ` Mike Snitzer [this message]
2020-09-24 7:17 ` Satya Tangirala
2020-09-24 13:46 ` Mike Snitzer
2020-09-24 15:45 ` Eric Biggers
2020-09-24 16:16 ` Mike Snitzer
2020-09-24 16:57 ` Eric Biggers
2020-09-24 1:21 ` Mike Snitzer
2020-09-24 7:38 ` Satya Tangirala
2020-09-24 14:23 ` Mike Snitzer
2020-10-15 22:05 ` Satya Tangirala
2020-09-24 7:48 ` Satya Tangirala
2020-09-24 13:40 ` Mike Snitzer
2020-10-15 21:55 ` Satya Tangirala
2020-09-09 23:44 ` [PATCH 3/3] dm: enable may_passthrough_inline_crypto on some targets Satya Tangirala
2020-09-22 0:49 ` Eric Biggers
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