Re: [RFC PATCH v10 00/48] ceph+fscrypt: full support

[Jeff Layton <jlayton@kernel.org>]

On Fri, 2022-01-28 at 12:39 -0800, Eric Biggers wrote:
> On Thu, Jan 27, 2022 at 06:08:40AM -0500, Jeff Layton wrote:
> > On Wed, 2022-01-26 at 18:14 -0800, Eric Biggers wrote:
> > > On Tue, Jan 11, 2022 at 02:15:20PM -0500, Jeff Layton wrote:
> > > > Still, I was able to run xfstests on this set yesterday. Bug #2 above
> > > > prevented all of the tests from passing, but it didn't oops! I call that
> > > > progress! Given that, I figured this is a good time to post what I have
> > > > so far.
> > > 
> > > One question: what sort of testing are you doing to show that the file contents
> > > and filenames being stored (i.e., sent by the client to the server in this case)
> > > have been encrypted correctly?  xfstests has tests that verify this for block
> > > device based filesystems; are you doing any equivalent testing?
> > > 
> > 
> > I've been testing this pretty regularly with xfstests, and the filenames
> > portion all seems to be working correctly. Parts of the content
> > encryption also seem to work ok. I'm still working that piece, so I
> > haven't been able to validate that part yet.
> > 
> > At the moment I'm working on switching the ceph client over to doing
> > sparse reads, which is necessary in order to be able to handle sparse
> > writes without filling in unwritten holes.
> 
> To clarify, I'm asking about the correctness of the ciphertext written to
> "disk", not about the user-visible filesystem behavior which is something
> different (but also super important as well, of course).  xfstests includes both
> types of tests.
> 
> Grepping for _verify_ciphertext_for_encryption_policy in xfstests will show the
> tests that verify the ciphertext written to disk.  I doubt that you're running
> those, as they rely on a block device.  So you'll need to write some equivalent
> tests.  In a pinch, you could simply check that the ciphertext is random rather
> than correct (that would at least show that it's not plaintext) like what
> generic/399 does.  But actually verifying its correctness would be ideal to
> ensure that nothing went wrong along the way.
> 

Got it. Yes, that would be a good thing. I'll have to see what I can do
once I get to the point of a fully-functioning prototype.
-- 
Jeff Layton <jlayton@kernel.org>