linux-kernel - Re: [PATCH 08/18] crypto: testmgr - run only subset of DH vectors based on config

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Message-ID: <87sfv2kufw.fsf@suse.de>
Date:   Thu, 09 Dec 2021 10:18:27 +0100
From:   Nicolai Stange <nstange@...e.de>
To:     Hannes Reinecke <hare@...e.de>
Cc:     Nicolai Stange <nstange@...e.de>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Stephan Müller <smueller@...onox.de>,
        Torsten Duwe <duwe@...e.de>, Zaibo Xu <xuzaibo@...wei.com>,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        David Howells <dhowells@...hat.com>,
        Jarkko Sakkinen <jarkko@...nel.org>,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        qat-linux@...el.com, keyrings@...r.kernel.org
Subject: Re: [PATCH 08/18] crypto: testmgr - run only subset of DH vectors based on config

Hannes Reinecke <hare@...e.de> writes:

> On 12/1/21 1:48 AM, Nicolai Stange wrote:
>> With the previous patches, the testmgr now has up to four test vectors for
>> DH which all test more or less the same thing:
>> - the two vectors from before this series,
>> - the vector for the ffdhe2048 group, enabled if
>>    CONFIG_CRYPTO_DH_GROUPS_RFC7919 is set and
>> - the vector for the modp2048 group, similarly enabled if
>>    CONFIG_CRYPTO_DH_GROUPS_RFC3526 is set.
>>
>> In order to avoid too much redundancy during DH testing, enable only a
>> subset of these depending on the kernel config:
>> - if CONFIG_CRYPTO_DH_GROUPS_RFC7919 is set, enable only the ffdhe2048
>>    vector,
>> - otherwise, if CONFIG_CRYPTO_DH_GROUPS_RFC3526 is set, enable only
>>    the modp2048 vector and
>> - only enable the original two vectors if neither of these options
>>    has been selected.
>>
>> Note that an upcoming patch will make the DH implementation to reject any
>> domain parameters not corresponding to some safe-prime group approved by
>> SP800-56Arev3 in FIPS mode. Thus, having CONFIG_FIPS enabled, but
>> both of CONFIG_CRYPTO_DH_GROUPS_RFC7919 and
>> CONFIG_CRYPTO_DH_GROUPS_RFC3526 unset wouldn't make much sense as it would
>> render the DH implementation unusable in FIPS mode. Conversely, any
>> reasonable configuration would ensure that the original, non-conforming
>> test vectors would not get to run in FIPS mode.
>>
>
> For some weird reason the NVMe spec mandates for its TLS profile the
> ffdhe3072 group, so I would prefer if you would be using that as the
> default group for testing.

Done for v2.

>
>> Signed-off-by: Nicolai Stange <nstange@...e.de>
>> ---
>>   crypto/testmgr.h | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/crypto/testmgr.h b/crypto/testmgr.h
>> index d18844c7499e..b295512c8f22 100644
>> --- a/crypto/testmgr.h
>> +++ b/crypto/testmgr.h
>> @@ -1331,8 +1331,7 @@ static const struct kpp_testvec dh_tv_template[] = {
>>   	.expected_a_public_size = 256,
>>   	.expected_ss_size = 256,
>>   	},
>> -#endif /* IS_ENABLED(CONFIG_CRYPTO_DH_GROUPS_RFC7919) */
>> -#if IS_ENABLED(CONFIG_CRYPTO_DH_GROUPS_RFC3526)
>> +#elif IS_ENABLED(CONFIG_CRYPTO_DH_GROUPS_RFC3526)
>>   	{
>>   	.secret =
>>   #ifdef __LITTLE_ENDIAN
>> @@ -1423,7 +1422,7 @@ static const struct kpp_testvec dh_tv_template[] = {
>>   	.expected_a_public_size = 256,
>>   	.expected_ss_size = 256,
>>   	},
>> -#endif /* IS_ENABLED(CONFIG_CRYPTO_DH_GROUPS_RFC3526) */
>> +#else
>>   	{
>>   	.secret =
>>   #ifdef __LITTLE_ENDIAN
>> @@ -1642,6 +1641,7 @@ static const struct kpp_testvec dh_tv_template[] = {
>>   	.expected_a_public_size = 256,
>>   	.expected_ss_size = 256,
>>   	},
>> +#endif
>>   };
>>     static const struct kpp_testvec curve25519_tv_template[] = {
>>
> ... and maybe add a config option to run a full test.

I didn't do this at this point, because I don't see much value in
running tests on more than one randomly selected DH group, i.e. on
ffdhe3072 and modp2048: both test vectors test the same code paths.

It might perhaps make sense to run tests for all the DH safe-prime
groups each for verifying that the resp. ->p primes are all correct. But
that would be a large TV dump and I'm not sure it would be desirable...

Thanks,

Nicolai

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