Re: Failing iotest 206

[Thomas Huth <thuth@redhat.com>]

On 20/07/2021 03.12, Eric Blake wrote:
> On Mon, Jul 19, 2021 at 10:06:01AM +0200, Thomas Huth wrote:
>>   Hi,
>>
>> iotest 206 fails for me with:
>>
> 
>> --- 206.out
>> +++ 206.out.bad
>> @@ -99,55 +99,19 @@
>>
>>   {"execute": "blockdev-create", "arguments": {"job-id": "job0", "options":
>> {"driver": "qcow2", "encrypt": {"cipher-alg": "twofish-128", "cipher-mode":
>> "ctr", "format": "luks", "hash-alg": "sha1", "iter-time": 10, "ivgen-alg":
>> "plain64", "ivgen-hash-alg": "md5", "key-secret": "keysec0"}, "file":
>> {"driver": "file", "filename": "TEST_DIR/PID-t.qcow2"}, "size": 33554432}}}
>>   {"return": {}}
>> +Job failed: Unsupported cipher algorithm twofish-128 with ctr mode
>>   {"execute": "job-dismiss", "arguments": {"id": "job0"}}
>>   {"return": {}}
> 
>>
>> Looks like it is missing a check for the availability of the corresponding
>> crypto stuff? Does anybody got a clue how to fix this?
> 
> What system is this on?

RHEL 8.4

> Which crypto library versions are installed?

gnutls-3.6.14-8.el8_3.x86_64
nettle-3.4.1-4.el8_3.x86_64

> I suspect this is related to Dan's effort to speed up crypto by
> favoring gnutls over nettle, where the switch in favored libraries
> failed to account for whether twofish-128 is supported?
> 
> https://lists.gnu.org/archive/html/qemu-devel/2021-07/msg03886.html

You're right, I've bisected the problem now, and the commit that introduced 
the issue is this one here:

commit 8bd0931f63008b1d50c8df75a611323a93c052bf
Author: Daniel P. Berrangé <berrange@redhat.com>
Date:   Fri Jul 2 17:38:33 2021 +0100

     crypto: prefer gnutls as the crypto backend if new enough

     If we have gnutls >= 3.6.13, then it has enough functionality
     and performance that we can use it as the preferred crypto
     backend.

     Reviewed-by: Eric Blake <eblake@redhat.com>
     Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

  Thomas