On 2025-09-09 14:15, Milan Broz wrote:
On 9/9/25 1:50 PM, Ingo Franzki wrote:
On 09.09.2025 13:47, Milan Broz wrote:
On 9/9/25 1:18 PM, Ingo Franzki wrote:
Please, revert my patches and run the same test on a clean
6.17.0-rc5 just
to verify that the patches do not introduce the bug.
With your patches reverted the combined mode fails the same way as
with your patches.
So they did not introduce the bug.
Please report it as cryptsetup issue with a reproducer so we can
later check it.
I don't think its a cryptsetup bug, its rather that dm-crypt is
missing something to deal with async HMAC ciphers.
The point is that PHMAC is a async-only cipher, with no sync variant.
I know, but there is no tracker for dm-crypt and what I like to have
some kind of upstream CI testing for PHMAC/PAES
even without mainframe hw (we already talked about a fake cipher
module).
Let me think about this a bit... You are suggesting a test kernel module
for
e.g. x64 which acts like the phmac/paes implementation in a asynchronous
way.
I'll discuss this with Ingo.
It is not an real issue as PHMAC is neither in released kernel nor in
cryptsetup yet, but we should have a test
coverage once it is merged.
On the other side, the async thing is a real pain, is there any plan
to switch to something better in future
(for dm-crypt and dm-integrity)?
Well, as of now all the s390 pkey things are by nature asynchronous.
Which
means at any time the key may get invalid. It is in the end a hardware
backed
key and thus if the hardware is changed (for example a 'live' guest
migration)
the key runs invalid and needs to be re-derived or re-fetched. I don't
see a
way to hide this and have a synchronous implementation instead.
I think on the contrary the need for asynchronous algorithms will
increase.
More and more platforms run virtual machines which exploit special
hardware
like AI accelerators and crypto co-processors and do support live guest
migration.
Well, that's future. However, it would be nice to have at least one
asynchronous
algorithm implementation available on a broad platform like x64 or arm
maybe only
for test of the dm-integrity layer.
Thanks,
Milan
