Re: [PATCH v5 00/11] blksnap - block devices snapshots module

Christoph Hellwig
2023-06-13T05:50:31Z

On Mon, Jun 12, 2023 at 09:19:11AM -0700, Eric Biggers wrote:
> On Mon, Jun 12, 2023 at 03:52:17PM +0200, Sergei Shtepa wrote:
> > Hi all.
> >
> > I am happy to offer a improved version of the Block Devices Snapshots
> > Module. It allows to create non-persistent snapshots of any block devices.
> > The main purpose of such snapshots is to provide backups of block devices.
> > See more in Documentation/block/blksnap.rst.
>
> How does blksnap interact with blk-crypto?
>
> I.e., what happens if a bio with a ->bi_crypt_context set is submitted to a
> block device that has blksnap active?
>
> If you are unfamiliar with blk-crypto, please read
> Documentation/block/inline-encryption.rst
>
> It looks like blksnap hooks into the block layer directly, via the new
> "blkfilter" mechanism. I'm concerned that it might ignore ->bi_crypt_context
> and write data to the disk in plaintext, when it is supposed to be encrypted.

Yeah. Same for integrity. I guess for now the best would be to
not allow attaching a filter to block devices that have encryption or
integrity enabled and then look into that as a separate project fully
reviewed by the respective experts.