On 7/10/19 3:34 PM, Eric Biggers wrote:
> On Wed, Jul 10, 2019 at 03:59:05PM +0000, Gary R Hook wrote:
>> On 7/9/19 8:57 PM, Eric Biggers wrote:
>>> On Wed, Jul 10, 2019 at 12:09:22AM +0000, Hook, Gary wrote:
>>>> The AES GCM function reuses an 'op' data structure, which members
>>>> contain values that must be cleared for each (re)use.
>>>>
>>>> This fix resolves a crypto self-test failure:
>>>> alg: aead: gcm-aes-ccp encryption test failed (wrong result) on test vector 2, cfg="two even aligned splits"
>>>>
>>>> Fixes: 36cf515b9bbe ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
>>>>
>>>> Signed-off-by: Gary R Hook <gary.hook@xxxxxxx>
>>>
>>> FYI, with this patch applied I'm still seeing another test failure:
>>>
>>> [ 2.140227] alg: aead: gcm-aes-ccp setauthsize unexpectedly succeeded on test vector "random: alen=264 plen=161 authsize=6 klen=32"; expected_error=-22
>>>
>>> Are you aware of that one too, and are you planning to fix it?
>>>
>>> - Eric
>>>
>>
>> I just pulled the latest on the master branch of cryptodev-2.6, built,
>> booted, and loaded our module. And I don't see that error. It must be new?
>
> Did you have CONFIG_CRYPTO_MANAGER_EXTRA_TESTS enabled? This failure was with a
> test vector that was generated randomly by the fuzz tests, so
> CONFIG_CRYPTO_MANAGER_EXTRA_TESTS=y is needed to reproduce it.
>
> You probably just need to update ccp_aes_gcm_setauthsize() to validate the
> authentication tag size.
Now I'm confused. I did need to fix that function, and AFAIK the tag for
GCM is always going to be 16 bytes (our AES_BLOCK_SIZE).
So, after making the small change, the above test passes, but now I
progress and get this error:
[ 1640.820781] alg: aead: gcm-aes-ccp setauthsize failed on test vector
"random: alen=29 plen=29 authsize=12 klen=32"; expected_error=0,
actual_error=1
Which is wholly unclear. Why would an authsize of 12 be okay for this
transformation? The GCM tag is a fixed size.
Nothing in the AEAD documentation jumps out at me. As I don't profess to
be a crypto expert, I'd appreciate any guidance on this subtle issue
that is eluding me...
Thanks
grh
