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From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: "Safford, David (GE Global Research, US)" <david.safford@ge.com>,
	Ken Goldman <kgold@linux.ibm.com>,
	Mimi Zohar <zohar@linux.ibm.com>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"stable@vger.kernel.org" <stable@vger.kernel.org>,
	"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: Thu, 31 Oct 2019 23:03:30 +0200	[thread overview]
Message-ID: <20191031210330.GA10507@linux.intel.com> (raw)
In-Reply-To: <1572361096.4812.3.camel@HansenPartnership.com>

On Tue, Oct 29, 2019 at 07:58:16AM -0700, James Bottomley wrote:
> On Tue, 2019-10-29 at 10:42 +0200, Jarkko Sakkinen wrote:
> > On Mon, Oct 21, 2019 at 02:39:39PM +0300, Jarkko Sakkinen wrote:
> > > On Thu, Oct 17, 2019 at 09:04:40PM +0300, Jarkko Sakkinen wrote:
> > > > On Wed, Oct 16, 2019 at 03:10:29PM -0400, James Bottomley wrote:
> > > > > On Wed, 2019-10-16 at 19:25 +0300, Jarkko Sakkinen wrote:
> > > > > > On Wed, Oct 16, 2019 at 08:34:12AM -0400, James Bottomley
> > > > > > wrote:
> > > > > > > reversible ciphers are generally frowned upon in random
> > > > > > > number
> > > > > > > generation, that's why the krng uses chacha20.  In general
> > > > > > > I think
> > > > > > > we shouldn't try to code our own mixing and instead should
> > > > > > > get the
> > > > > > > krng to do it for us using whatever the algorithm du jour
> > > > > > > that the
> > > > > > > crypto guys have blessed is.  That's why I proposed adding
> > > > > > > the TPM
> > > > > > > output to the krng as entropy input and then taking the
> > > > > > > output of
> > > > > > > the krng.
> > > > > > 
> > > > > > It is already registered as hwrng. What else?
> > > > > 
> > > > > It only contributes entropy once at start of OS.
> > > > 
> > > > Ok.
> > > > 
> > > > > >  Was the issue that it is only used as seed when the rng is
> > > > > > init'd
> > > > > > first? I haven't at this point gone to the internals of krng.
> > > > > 
> > > > > Basically it was similar to your xor patch except I got the
> > > > > kernel rng
> > > > > to do the mixing, so it would use the chacha20 cipher at the
> > > > > moment
> > > > > until they decide that's unsafe and change it to something
> > > > > else:
> > > > > 
> > > > > https://lore.kernel.org/linux-crypto/1570227068.17537.4.camel@H
> > > > > ansenPartnership.com/
> > > > > 
> > > > > It uses add_hwgenerator_randomness() to do the mixing.  It also
> > > > > has an
> > > > > unmixed source so that read of the TPM hwrng device works as
> > > > > expected.
> > > > 
> > > > Thinking that could this potentially racy? I.e. between the calls
> > > > something else could eat the entropy added?
> > > 
> > > Also, what is wrong just taking one value from krng and mixing
> > > it with a value from TPM RNG where needed? That would be non-racy
> > > too.
> > 
> > I guess we can move forward with this?
> 
> Sure I suppose; can we can figure out how to get the mixing function du
> jour exposed?

Maybe it is best to reflect the whole issue in the context of the
Sumit's 2nd patch set, which adds ARM TEE support in order to move
forward.

/Jarkko

  reply	other threads:[~2019-10-31 21:03 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
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 [this message]
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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