Received-SPF: pass (google.com: best guess record for domain of linux-crypto-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Thu, 3 Oct 2019 14:43:44 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To:     Mimi Zohar <zohar@linux.ibm.com>
Cc:     linux-integrity@vger.kernel.org, stable@vger.kernel.org,
        David Howells <dhowells@redhat.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        "open list:ASYMMETRIC KEYS" <keyrings@vger.kernel.org>,
        "open list:CRYPTO API" <linux-crypto@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KEYS: asym_tpm: Switch to get_random_bytes()
Message-ID: <20191003114344.GG8933@linux.intel.com>
References: <20190926171601.30404-1-jarkko.sakkinen@linux.intel.com>
 <1570024819.4999.119.camel@linux.ibm.com>
 <20191003114119.GF8933@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20191003114119.GF8933@linux.intel.com>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-crypto-owner@vger.kernel.org
Precedence: bulk

On Thu, Oct 03, 2019 at 02:41:19PM +0300, Jarkko Sakkinen wrote:
> On Wed, Oct 02, 2019 at 10:00:19AM -0400, Mimi Zohar wrote:
> > On Thu, 2019-09-26 at 20:16 +0300, Jarkko Sakkinen wrote:
> > > Only the kernel random pool should be used for generating random numbers.
> > > TPM contributes to that pool among the other sources of entropy. In here it
> > > is not, agreed, absolutely critical because TPM is what is trusted anyway
> > > but in order to remove tpm_get_random() we need to first remove all the
> > > call sites.
> > 
> > At what point during boot is the kernel random pool available? ?Does
> > this imply that you're planning on changing trusted keys as well?
> 
> Well trusted keys *must* be changed to use it. It is not a choice
> because using a proprietary random number generator instead of defacto
> one in the kernel can be categorized as a *regression*.
> 
> Also, TEE trusted keys cannot use the TPM option.
> 
> If it was not initialized early enough we would need fix that too.
> 
> I don't think there should be a problem anyway since encrypted keys is
> already using get_random_bytes().

Looking at asym_tpm.c the implementation copies all the anti-patterns
from trusted keys, which is really unfortunate. I don't know how that
has passed through all the filters.

/Jarkko