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Date:   Mon, 12 Jun 2023 22:50:12 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Sergei Shtepa <sergei.shtepa@veeam.com>, axboe@kernel.dk,
        hch@infradead.org, corbet@lwn.net, snitzer@kernel.org,
        viro@zeniv.linux.org.uk, brauner@kernel.org, dchinner@redhat.com,
        willy@infradead.org, dlemoal@kernel.org, linux@weissschuh.net,
        jack@suse.cz, ming.lei@redhat.com, linux-block@vger.kernel.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v5 00/11] blksnap - block devices snapshots module
Message-ID: <ZIgDlA/nMQIMqeLU@infradead.org>
References: <20230612135228.10702-1-sergei.shtepa@veeam.com>
 <20230612161911.GA1200@sol.localdomain>
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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.