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From:   Stephan Mueller <smueller@chronox.de>
To:     Nicolai Stange <nstange@suse.de>,
        Herbert Xu <herbert@gondor.apana.org.au>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Hannes Reinecke <hare@suse.de>, Torsten Duwe <duwe@suse.de>,
        Zaibo Xu <xuzaibo@huawei.com>,
        Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
        David Howells <dhowells@redhat.com>,
        Jarkko Sakkinen <jarkko@kernel.org>,
        linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org,
        qat-linux@intel.com, keyrings@vger.kernel.org, simo@redhat.com,
        Eric Biggers <ebiggers@kernel.org>, Petr Vorel <pvorel@suse.cz>
Subject: Re: [v2 PATCH] crypto: api - Disallow sha1 in FIPS-mode while allowing hmac(sha1)
Date:   Wed, 26 Jan 2022 10:01:17 +0100
Message-ID: <3615781.PPvlf9ziaL@tauon.chronox.de>
In-Reply-To: <YeFWnscvXtv73KBl@gondor.apana.org.au>
References: <20211209090358.28231-1-nstange@suse.de> <87k0f2hefl.fsf@suse.de> <YeFWnscvXtv73KBl@gondor.apana.org.au>
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Am Freitag, 14. Januar 2022, 11:55:26 CET schrieb Herbert Xu:

Hi Herbert,

> 
> > This looks all good to me, but as !->fips_allowed tests aren't skipped
> > over anymore now, it would perhaps make sense to make their failure
> > non-fatal in FIPS mode. Because in FIPS mode a failure could mean a
> > panic and some of the existing TVs might not pass because of e.g. some
> > key length checks or so active only for fips_enabled...
> 
> You mean a buggy non-FIPS algorithm that fails when tested in
> FIPS mode?  I guess we could skip the panic in that case if
> everyone is happy with that.  Stephan?

As we consider FIPS 140-3, we can allow a "degrated mode of operation". A 
degraded mode of operation disables only the algorithm that caused the 
failure. With a failing self test and not having a panic(), the offending 
algorithm implementation will not be available to the kernel crypto API and 
thus to a user.

In this case, we can replace the panic with a graceful error.

If that change is applied, I would like to mention to anybody that wants to 
backport the change: this change is not appropriate for FIPS 140-2.

Ciao
Stephan