linux-kernel - Re: [PATCH v2 0/7] crypto: sha256 - Merge 2 separate C implementations into 1, put into separate library

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Date:   Mon, 19 Aug 2019 21:38:19 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/7] crypto: sha256 - Merge 2 separate C
 implementations into 1, put into separate library

Hi,

On 19-08-19 17:08, Ard Biesheuvel wrote:
> On Sat, 17 Aug 2019 at 17:24, Hans de Goede <hdegoede@...hat.com> wrote:
>>
>> Hi All,
>>
>> Here is v2 of my patch series refactoring the current 2 separate SHA256
>> C implementations into 1 and put it into a separate library.
>>
>> There are 3 reasons for this:
>>
>> 1) Remove the code duplication of having 2 separate implementations
>>
>> 2) Offer a separate library SHA256 implementation which can be used
>> without having to call crypto_alloc_shash first. This is especially
>> useful for use during early boot when crypto_alloc_shash does not
>> work yet.
>>
>> 3) Having the purgatory code using the same code as the crypto subsys means
>> that the purgratory code will be tested by the crypto subsys selftests.
>>
>> This has been tested on x86, including checking that kecec still works.
>>
>> This has NOT been tested on s390, if someone with access to s390 can
>> test that things still build with this series applied and that
>> kexec still works, that would be great.
>>
>> Changes in v2:
>> - Use put_unaligned_be32 to store the hash to allow callers to use an
>>    unaligned buffer for storing the hash
>> - Add a comment to include/crypto/sha256.h explaining that these functions
>>    now may be used outside of the purgatory too (and that using the crypto
>>    API instead is preferred)
>> - Add sha224 support to the lib/crypto/sha256 library code
>> - Make crypto/sha256_generic.c not only use sha256_transform from
>>    lib/crypto/sha256.c but also switch it to using sha256_init, sha256_update
>>    and sha256_final from there so that the crypto subsys selftests fully test
>>    the lib/crypto/sha256.c implementation
>>
> 
> This looks fine to me, although I agree with Eric's feedback regarding
> further cleanups.

Ack, as I already told Eric I'm happy to do a follow up series with
the necessary local static function renames so that we can then merge
sha256.h into sha.h .

> Also, now that we have a C library, I'd like to drop
> the dependency of the mips and x86 sha256 algo implementations up
> sha256_generic.c, and use the library directly instead (so that
> sha256-generic is no longer needed on x86 or mips)

I assume this is more of a generic remark and not targeted towards me?

Regards,

Hans