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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: David Safford <david.safford@ge.com>,
	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()
Date: Fri, 4 Oct 2019 01:10:42 +0300	[thread overview]
Message-ID: <20191003221042.GA3363@linux.intel.com> (raw)
In-Reply-To: <20191003215743.GB30511@linux.intel.com>

On Fri, Oct 04, 2019 at 12:57:43AM +0300, Jarkko Sakkinen wrote:
> On Fri, Oct 04, 2019 at 12:51:25AM +0300, Jarkko Sakkinen wrote:
> > On Thu, Oct 03, 2019 at 02:53:47PM -0400, Mimi Zohar wrote:
> > > [Cc'ing David Safford]
> > > 
> > > On Thu, 2019-10-03 at 20:58 +0300, Jarkko Sakkinen wrote:
> > > > On Thu, Oct 03, 2019 at 09:02:32AM -0400, Mimi Zohar wrote:
> > > > > On Thu, 2019-10-03 at 14:41 +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*.
> > > > > 
> > > > > I really don't see how using the TPM random number for TPM trusted
> > > > > keys would be considered a regression.  That by definition is a
> > > > > trusted key.  If anything, changing what is currently being done would
> > > > > be the regression. 
> > > > 
> > > > It is really not a TPM trusted key. It trusted key that gets sealed with
> > > > the TPM. The key itself is used in clear by kernel. The random number
> > > > generator exists in the kernel to for a reason.
> > > > 
> > > > It is without doubt a regression.
> > > 
> > > You're misusing the term "regression" here.  A regression is something
> > > that previously worked and has stopped working.  In this case, trusted
> > > keys has always been based on the TPM random number generator.  Before
> > > changing this, there needs to be some guarantees that the kernel
> > > random number generator has a pool of random numbers early, on all
> > > systems including embedded devices, not just servers.
> > 
> > I'm not using the term regression incorrectly here. Wrong function
> > was used to generate random numbers for the payload here. It is an
> > obvious bug.
> 
> At the time when trusted keys was introduced I'd say that it was a wrong
> design decision and badly implemented code. But you are right in that as
> far that code is considered it would unfair to speak of a regression.
> 
> asym-tpm.c on the other hand this is fresh new code. There has been
> *countless* of discussions over the years that random numbers should
> come from multiple sources of entropy. There is no other categorization
> than a bug for the tpm_get_random() there.

Saying that regression is something that "stopped working" is very blunt
and naive definition of regression, and is not true. Any misbehaviour
can be categorized as a regression.

/Jarkko

  parent reply	other threads:[~2019-10-03 22:10 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-26 17:16 Jarkko Sakkinen
2019-09-28 18:05 ` Jerry Snitselaar
2019-10-01 20:54   ` Jarkko Sakkinen
2019-10-02 14:00 ` Mimi Zohar
2019-10-03 11:41   ` Jarkko Sakkinen
2019-10-03 11:43     ` Jarkko Sakkinen
2019-10-03 13:02     ` Mimi Zohar
2019-10-03 17:58       ` Jarkko Sakkinen
2019-10-03 18:53         ` Mimi Zohar
2019-10-03 21:51           ` Jarkko Sakkinen
2019-10-03 21:57             ` Jarkko Sakkinen
2019-10-03 22:08               ` Mimi Zohar
2019-10-03 23:59                 ` James Bottomley
2019-10-04 18:22                   ` Jarkko Sakkinen
2019-10-04 18:24                     ` James Bottomley
2019-10-04 18:33                       ` Jerry Snitselaar
2019-10-04 18:42                         ` James Bottomley
2019-10-04 20:07                           ` Jerry Snitselaar
2019-10-04 20:11                             ` Jerry Snitselaar
2019-10-04 22:11                               ` James Bottomley
2019-10-06  0:38                                 ` Mimi Zohar
2019-10-06 23:52                                   ` Jarkko Sakkinen
2019-10-07 18:08                                     ` Mimi Zohar
2019-10-04 18:20                 ` Jarkko Sakkinen
2019-10-03 22:10               ` Jarkko Sakkinen [this message]
2019-10-04 13:26           ` Safford, David (GE Global Research, US)
2019-10-04 18:27             ` Jarkko Sakkinen
2019-10-04 18:30               ` Jarkko Sakkinen
2019-10-04 19:56               ` Safford, David (GE Global Research, US)
2019-10-07  0:05                 ` Jarkko Sakkinen
2019-10-07 22:13                   ` Ken Goldman
2019-10-08 23:49                     ` Jarkko Sakkinen
2019-10-08 23:53                       ` Jarkko Sakkinen
2019-10-09  7:10                         ` Pascal Van Leeuwen
2019-10-09  7:33                         ` Jarkko Sakkinen
2019-10-09  7:41                           ` Jarkko Sakkinen
2019-10-09  8:09                             ` Pascal Van Leeuwen
2019-10-14 19:11                               ` Jarkko Sakkinen
2019-10-09  8:02                           ` Pascal Van Leeuwen
2019-10-09 12:11                         ` Safford, David (GE Global Research, US)
2019-10-14 19:00                           ` Jarkko Sakkinen
2019-10-14 19:29                             ` Jarkko Sakkinen
2019-10-14 19:29                             ` James Bottomley
2019-10-16 11:00                               ` Jarkko Sakkinen
2019-10-16 12:34                                 ` James Bottomley
2019-10-16 16:25                                   ` Jarkko Sakkinen
2019-10-16 19:10                                     ` James Bottomley
2019-10-17 12:52                                       ` Sumit Garg
2019-10-17 12:58                                         ` James Bottomley
2019-10-17 18:04                                       ` Jarkko Sakkinen
2019-10-21 11:39                                         ` Jarkko Sakkinen
2019-10-29  8:42                                           ` Jarkko Sakkinen
2019-10-29 14:58                                             ` James Bottomley
2019-10-31 21:03                                               ` Jarkko Sakkinen
2019-10-18  7:32                                   ` Janne Karhunen
2019-10-03 18:02       ` Jarkko Sakkinen
2019-10-03 18:15         ` Jarkko Sakkinen
2019-10-07 10:33     ` Janne Karhunen

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