Re: [PATCH] crypto: testmgr - block Crypto API xxhash64 in FIPS mode

[Joachim Vandersmissen]

Hi Herbert,

I don't think this one can be applied yet since dm-integrity still uses 
xxhash64 through the crypto API. This would break fips=1 systems that 
use it.

Kind regards,
Joachim

On 3/14/26 12:11 AM, Herbert Xu wrote:
> On Tue, Mar 03, 2026 at 12:05:09AM -0600, Joachim Vandersmissen wrote:
> > xxhash64 is not a cryptographic hash algorithm, but is offered in the
> > same API (shash) as actual cryptographic hash algorithms such as
> > SHA-256. The Cryptographic Module Validation Program (CMVP), managing
> > FIPS certification, believes that this could cause confusion. xxhash64
> > must therefore be blocked in FIPS mode.
> >
> > The only usage of xxhash64 in the kernel is btrfs. Commit fe11ac191ce0
> > ("btrfs: switch to library APIs for checksums") recently modified the
> > btrfs code to use the lib/crypto API, avoiding the Kernel Cryptographic
> > API. Consequently, the removal of xxhash64 from the Crypto API in FIPS
> > mode should now have no impact on btrfs usage.
> >
> > Signed-off-by: Joachim Vandersmissen <git@xxxxxxxxx>
> > ---
> >   crypto/testmgr.c | 1 -
> >   1 file changed, 1 deletion(-)
> Patch applied.  Thanks.