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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Thu, 20 Jun 2019 15:52:30 +0200
Message-ID: <CAKv+Gu-ZETNJh2VzUkpbQUmYv6Zqb7nVj91bxuxKoNAJwgON=w@mail.gmail.com>
Subject: Re: [PATCH v3 0/6] crypto: switch to crypto API for ESSIV generation
To:     Milan Broz <gmazyland@gmail.com>
Cc:     "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Eric Biggers <ebiggers@google.com>,
        device-mapper development <dm-devel@redhat.com>,
        linux-fscrypt@vger.kernel.org,
        Gilad Ben-Yossef <gilad@benyossef.com>
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On Thu, 20 Jun 2019 at 15:14, Milan Broz <gmazyland@gmail.com> wrote:
>
> On 20/06/2019 14:09, Milan Broz wrote:
> > On 20/06/2019 13:54, Ard Biesheuvel wrote:
> >> On Thu, 20 Jun 2019 at 13:22, Milan Broz <gmazyland@gmail.com> wrote:
> >>>
> >>> On 19/06/2019 18:29, Ard Biesheuvel wrote:
> >>>> This series creates an ESSIV template that produces a skcipher or AEAD
> >>>> transform based on a tuple of the form '<skcipher>,<cipher>,<shash>'
> >>>> (or '<aead>,<cipher>,<shash>' for the AEAD case). It exposes the
> >>>> encapsulated sync or async skcipher/aead by passing through all operations,
> >>>> while using the cipher/shash pair to transform the input IV into an ESSIV
> >>>> output IV.
> >>>>
> >>>> This matches what both users of ESSIV in the kernel do, and so it is proposed
> >>>> as a replacement for those, in patches #2 and #4.
> >>>>
> >>>> This code has been tested using the fscrypt test suggested by Eric
> >>>> (generic/549), as well as the mode-test script suggested by Milan for
> >>>> the dm-crypt case. I also tested the aead case in a virtual machine,
> >>>> but it definitely needs some wider testing from the dm-crypt experts.
> >>>>
> >>>> Changes since v2:
> >>>> - fixed a couple of bugs that snuck in after I'd done the bulk of my
> >>>>   testing
> >>>> - some cosmetic tweaks to the ESSIV template skcipher setkey function
> >>>>   to align it with the aead one
> >>>> - add a test case for essiv(cbc(aes),aes,sha256)
> >>>> - add an accelerated implementation for arm64 that combines the IV
> >>>>   derivation and the actual en/decryption in a single asm routine
> >>>
> >>> I run tests for the whole patchset, including some older scripts and seems
> >>> it works for dm-crypt now.
> >>>
> >>
> >> Thanks Milan, that is really helpful.
> >>
> >> Does this include configurations that combine authenc with essiv?
> >
> > Hm, seems that we are missing these in luks2-integrity-test. I'll add them there.
> >
> > I also used this older test
> > https://gitlab.com/omos/dm-crypt-test-scripts/blob/master/root/test_dmintegrity.sh
> >
> > (just aes-gcm-random need to be commented out, we never supported this format, it was
> > written for some devel version)
> >
> > But seems ESSIV is there tested only without AEAD composition...
> >
> > So yes, this AEAD part need more testing.
>
> And unfortunately it does not work - it returns EIO on sectors where it should not be data corruption.
>
> I added few lines with length-preserving mode with ESSIV + AEAD, please could you run luks2-integrity-test
> in cryptsetup upstream?
>
> This patch adds the tests:
> https://gitlab.com/cryptsetup/cryptsetup/commit/4c74ff5e5ae328cb61b44bf99f98d08ffee3366a
>
> It is ok on mainline kernel, fails with the patchset:
>
> # ./luks2-integrity-test
> [aes-cbc-essiv:sha256:hmac-sha256:128:512][FORMAT][ACTIVATE]sha256sum: /dev/mapper/dmi_test: Input/output error
> [FAIL]
>  Expecting ee501705a084cd0ab6f4a28014bcf62b8bfa3434de00b82743c50b3abf06232c got .
>
> FAILED backtrace:
> 77 ./luks2-integrity-test
> 112 intformat ./luks2-integrity-test
> 127 main ./luks2-integrity-test
>

OK, I will investigate.

I did my testing in a VM using a volume that was created using a
distro kernel, and mounted and used it using a kernel with these
changes applied.

Likewise, if I take a working key.img and mode-test.img, i can mount
it and use it on the system running these patches.

I noticed that this test uses algif_skcipher not algif_aead when it
formats the volume, and so I wonder if the way userland creates the
image is affected by this?