Re: [PATCH v10 2/7] fs: crypto: invoke crypto API for ESSIV handling

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On Mon, 12 Aug 2019 at 22:47, Eric Biggers <ebiggers@kernel.org> wrote:
>
> On Mon, Aug 12, 2019 at 05:53:19PM +0300, Ard Biesheuvel wrote:
> > Instead of open coding the calculations for ESSIV handling, use a
> > ESSIV skcipher which does all of this under the hood.
> >
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>
> This looks fine (except for one comment below), but this heavily conflicts with
> the fscrypt patches planned for v5.4.  So I suggest moving this to the end of
> the series and having Herbert take only 1-6, and I'll apply this one to the
> fscrypt tree later.
>

I think the same applies to dm-crypt: at least patch #7 cannot be
applied until my eboiv patch is applied there as well, but [Milan
should confirm] I'd expect them to prefer taking those patches via the
dm tree anyway.

Herbert, what would you prefer:
- taking a pull request from a [signed] tag based on v4.3-rc1 that
contains patches #1, #4, #5 and #6, allowing Eric and Milan/Mike to
merge it as well, and apply the respective fscrypt and dm-crypt
changes on top
- just take patches #1, #4, #5 and #6 as usual, and let the fscrypt
and dm-crypt changes be reposted to the respective lists during the
next cycle


>
> > ---
> >  fs/crypto/Kconfig           |  1 +
> >  fs/crypto/crypto.c          |  5 --
> >  fs/crypto/fscrypt_private.h |  9 --
> >  fs/crypto/keyinfo.c         | 92 +-------------------
> >  4 files changed, 4 insertions(+), 103 deletions(-)
> >
> > diff --git a/fs/crypto/Kconfig b/fs/crypto/Kconfig
> > index 5fdf24877c17..6f3d59b880b7 100644
> > --- a/fs/crypto/Kconfig
> > +++ b/fs/crypto/Kconfig
> > @@ -5,6 +5,7 @@ config FS_ENCRYPTION
> >       select CRYPTO_AES
> >       select CRYPTO_CBC
> >       select CRYPTO_ECB
> > +     select CRYPTO_ESSIV
> >       select CRYPTO_XTS
> >       select CRYPTO_CTS
> >       select KEYS
>
> In v5.3 I removed the 'select CRYPTO_SHA256', so now ESSIV shouldn't be selected
> here either.  Instead we should just update the documentation:
>
> diff --git a/Documentation/filesystems/fscrypt.rst b/Documentation/filesystems/fscrypt.rst
> index 82efa41b0e6c02..a1e2ab12a99943 100644
> --- a/Documentation/filesystems/fscrypt.rst
> +++ b/Documentation/filesystems/fscrypt.rst
> @@ -193,7 +193,8 @@ If unsure, you should use the (AES-256-XTS, AES-256-CTS-CBC) pair.
>  AES-128-CBC was added only for low-powered embedded devices with
>  crypto accelerators such as CAAM or CESA that do not support XTS.  To
>  use AES-128-CBC, CONFIG_CRYPTO_SHA256 (or another SHA-256
> -implementation) must be enabled so that ESSIV can be used.
> +implementation) and CONFIG_CRYPTO_ESSIV must be enabled so that ESSIV
> +can be used.
>
>  Adiantum is a (primarily) stream cipher-based mode that is fast even
>  on CPUs without dedicated crypto instructions.  It's also a true