[dm-devel] [PATCH 2/3] dm: add support for passing through inline crypto support

[Eric Biggers]

On Wed, Sep 09, 2020 at 11:44:21PM +0000, Satya Tangirala wrote:
> From: Eric Biggers <ebiggers at 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 at google.com>
> Co-developed-by: Satya Tangirala <satyat at google.com>
> Signed-off-by: Satya Tangirala <satyat at 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?

- Eric